Human Respiratory System Quiz
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Questions and Answers

What is the role of the diaphragm during inhalation?

  • It remains relaxed to allow for air entry.
  • It contracts to create negative pressure in the chest cavity. (correct)
  • It pulls the lungs apart to increase volume.
  • It creates positive pressure in the lungs.

    • How many lobes does the left lung have?

  • Four lobes.
  • Three lobes.
  • Two lobes. (correct)
  • One lobe.

    • What structure connects the trachea to the lungs?

  • Alveolar sacs.
  • Diaphragm.
  • Bronchi. (correct)
  • Pulmonary artery.

    • What occurs during gas exchange in the alveoli?

    <p>Oxygen diffuses from the alveoli into the blood.</p> Signup and view all the answers

    What layer of the lungs is in contact with the chest wall?

    <p>Parietal layer.</p> Signup and view all the answers

    What blood vessels transport oxygenated blood from the lungs to the heart?

    <p>Pulmonary vein.</p> Signup and view all the answers

    Which structure does not play a role in the upper respiratory system?

    <p>Bronchi.</p> Signup and view all the answers

    During exhalation, what happens to the diaphragm?

    <p>It relaxes, creating positive pressure.</p> Signup and view all the answers

    Which of the following correctly describes the flow of unoxygenated blood to the lungs?

    <p>Through the pulmonary artery to the lungs.</p> Signup and view all the answers

    What function does serous fluid serve between the layers of the lungs?

    <p>It provides lubrication for smooth movement.</p> Signup and view all the answers

    What is the primary function of the lungs?

    <p>To remove carbon dioxide and replenish oxygen</p> Signup and view all the answers

    What divides the right lung into lobes?

    <p>The bronchi</p> Signup and view all the answers

    Which layer surrounds the lungs?

    <p>Visceral layer</p> Signup and view all the answers

    During inhalation, which action does the diaphragm perform?

    <p>It contracts and lowers</p> Signup and view all the answers

    What is the purpose of the pulmonary arteries?

    <p>To transport deoxygenated blood to the lungs for oxygenation</p> Signup and view all the answers

    What occurs in the capillaries during gas exchange?

    <p>Oxygen diffuses from the alveoli into the capillaries</p> Signup and view all the answers

    Which of the following is NOT part of the lower respiratory system?

    <p>Nasal cavities</p> Signup and view all the answers

    What is the role of serous fluid in the lungs?

    <p>To prevent friction between layers</p> Signup and view all the answers

    What is the main role of the lungs in the respiratory system?

    <p>To remove carbon dioxide and supply oxygen</p> Signup and view all the answers

    Which structure acts as the primary site for gas exchange in the lungs?

    <p>Alveoli</p> Signup and view all the answers

    What happens during inhalation?

    <p>The diaphragm contracts and flattens</p> Signup and view all the answers

    What is the function of the visceral pleura around the lungs?

    <p>To attach directly to the lung surface</p> Signup and view all the answers

    How many lobes are present in the right lung?

    <p>Three lobes</p> Signup and view all the answers

    What is the primary role of the diaphragm during exhalation?

    <p>To relax, creating positive pressure to force air out</p> Signup and view all the answers

    What do the pulmonary arteries carry to the lungs?

    <p>Deoxygenated blood</p> Signup and view all the answers

    Which structure does NOT enter the lungs at the hilum along with the bronchi?

    <p>Alveoli</p> Signup and view all the answers

    What characteristic defines the alveoli in the lungs?

    <p>They are grape-like structures where gas exchange occurs</p> Signup and view all the answers

    What is created by the diaphragm's movement during inhalation?

    <p>Negative pressure that draws air in</p> Signup and view all the answers

    What principle explains that pressure is inversely related to volume in gases?

    <p>Boyle's Law</p> Signup and view all the answers

    What occurs when air enters the pleural cavity, breaking the bond between the pleurae?

    <p>Atelectasis</p> Signup and view all the answers

    During inhalation, what direction does air flow in relation to pressure?

    <p>From high to low pressure</p> Signup and view all the answers

    Which muscle movement contributes to the change in thoracic cavity volume during breathing?

    <p>Diaphragm and rib cage movement</p> Signup and view all the answers

    What happens to pressure inside the thoracic cavity as the volume increases during inhalation?

    <p>Pressure decreases</p> Signup and view all the answers

    What is the most common cause of chronic bronchitis?

    <p>Cigarette smoking</p> Signup and view all the answers

    Which term describes individuals with emphysema who exhibit heavy breathing and a pink coloration?

    <p>Pink puffers</p> Signup and view all the answers

    How does increased resistance during breathing affect energy demand?

    <p>It increases energy demand for ventilation.</p> Signup and view all the answers

    What describes chronic bronchitis and its effect on airways?

    <p>It leads to inflammation and overproduction of mucus.</p> Signup and view all the answers

    Which of the following is a characteristic of emphysema?

    <p>Loss of elastic tissues in the lungs.</p> Signup and view all the answers

    What triggers asthma-related symptoms?

    <p>Irritation from exercise or allergens</p> Signup and view all the answers

    What is a defining feature of Chronic Obstructive Pulmonary Disease (COPD)?

    <p>It results in irreversible airflow restriction.</p> Signup and view all the answers

    What is 'compliance' in the context of respiratory physiology?

    <p>The ability of the lungs to expand.</p> Signup and view all the answers

    What indicates how easily the lungs expand?

    <p>Compliance of the lungs</p> Signup and view all the answers

    What primarily affects the resistance of the lungs during ventilation?

    <p>Muscular activity of pulmonary ventilation</p> Signup and view all the answers

    Which condition is characterized by chronic inflammation and excessive mucus production in the airways?

    <p>Chronic bronchitis</p> Signup and view all the answers

    What occurs when both tissue oxygen demand and carbon dioxide levels increase?

    <p>Alveolar PO2 decreases</p> Signup and view all the answers

    Which disease often leads to decreased lung elasticity?

    <p>Emphysema</p> Signup and view all the answers

    How does increased pulmonary compliance affect respiratory function?

    <p>It requires less muscular effort to breathe.</p> Signup and view all the answers

    What is the primary role of respiratory control centers in the body?

    <p>To adjust respiratory rate and tidal volume</p> Signup and view all the answers

    In patients with COPD, which symptom is common due to airflow limitation?

    <p>Wheezing and breathlessness</p> Signup and view all the answers

    What is a significant effect of a blockage in the trachea on respiratory physiology?

    <p>Decreased oxygen uptake by tissues</p> Signup and view all the answers

    Chronic bronchitis and emphysema are both types of which disease category?

    <p>Chronic obstructive pulmonary disease (COPD)</p> Signup and view all the answers

    What is the main function of the accessory expiratory muscles?

    <p>To decrease thoracic cavity volume quickly</p> Signup and view all the answers

    Which respiratory volume represents the amount of air moved in or out during normal quiet breathing?

    <p>Tidal volume (VT)</p> Signup and view all the answers

    What is the volume of air that remains in the lungs after maximal exhalation?

    <p>Residual volume</p> Signup and view all the answers

    Which volume indicates the amount of air left in the lungs if they were allowed to collapse?

    <p>Minimal volume</p> Signup and view all the answers

    Which muscles push the diaphragm upward during expiration?

    <p>Abdominal muscles</p> Signup and view all the answers

    The main purpose of pulmonary function tests is to measure what?

    <p>Respiratory volumes and airflow rates</p> Signup and view all the answers

    What is the characteristic of inspiratory reserve volume (IRV)?

    <p>Amount of additional air inhaled beyond tidal volume</p> Signup and view all the answers

    What happens to thoracic cavity volume during forced expiration?

    <p>It decreases quickly</p> Signup and view all the answers

    Which of the following is NOT measured in pulmonary function tests?

    <p>Heart rate</p> Signup and view all the answers

    Which accessory muscle mainly helps in depressurizing the thoracic cavity?

    <p>Transversus thoracis</p> Signup and view all the answers

    Which of the following is a chronic obstructive pulmonary disease (COPD)?

    <p>Chronic Bronchitis</p> Signup and view all the answers

    What primarily differentiates chronic bronchitis from emphysema?

    <p>Chronic bronchitis involves airway inflammation, while emphysema involves alveolar destruction.</p> Signup and view all the answers

    Which group of respiratory centers is primarily responsible for inspiration?

    <p>Dorsal Respiratory Group (DRG)</p> Signup and view all the answers

    How do pulmonary diseases like COPD affect lung compliance?

    <p>They decrease lung compliance.</p> Signup and view all the answers

    What role do chemoreceptors play in the control of respiration?

    <p>They detect blood levels of oxygen, carbon dioxide, and pH.</p> Signup and view all the answers

    Which of the following physiological changes occurs mainly during expiration?

    <p>Use of accessory muscles for forced breathing</p> Signup and view all the answers

    What is the primary function of the Ventral Respiratory Group (VRG)?

    <p>Control expiration during increased breathing demands</p> Signup and view all the answers

    Which mechanism regulates the respiratory rhythmicity within the brainstem?

    <p>The medulla oblongata</p> Signup and view all the answers

    What effect does COPD typically have on respiratory resistance?

    <p>It increases resistance due to airway obstruction.</p> Signup and view all the answers

    Which component of the Dorsal Respiratory Group (DRG) is primarily involved in detecting stretch?

    <p>Baroreceptors</p> Signup and view all the answers

    What is the primary function of the apneustic centers in the brainstem?

    <p>Stimulate inhalation</p> Signup and view all the answers

    How do the pneumotaxic centers affect the respiratory cycle?

    <p>They shorten inhalation duration</p> Signup and view all the answers

    Which of the following correctly describes the role of higher centers in respiratory control?

    <p>They can modify the activity of pneumotaxic centers</p> Signup and view all the answers

    What information influences the degree of stimulation from the apneustic centers?

    <p>Sensory information from the vagus nerve</p> Signup and view all the answers

    What effect does increased output from the pneumotaxic centers have on breathing rate?

    <p>It increases the respiratory rate</p> Signup and view all the answers

    What is the primary component of the respiratory mucosa lining the nasal cavity?

    <p>Pseudostratified ciliated columnar epithelium</p> Signup and view all the answers

    What mechanism helps to clear mucus and debris from the respiratory tract?

    <p>Mucociliary escalator</p> Signup and view all the answers

    What type of epithelium lines the inferior portions of the pharynx?

    <p>Stratified squamous epithelium</p> Signup and view all the answers

    What role does the lamina propria serve in the respiratory mucosa?

    <p>Providing structural support and containing mucous glands</p> Signup and view all the answers

    Which of the following best describes the function of the sticky mucus produced in the respiratory system?

    <p>Traps debris particles</p> Signup and view all the answers

    What replaces damaged or old epithelial cells in the respiratory tract?

    <p>Epithelial stem cells</p> Signup and view all the answers

    Which statement about the gas exchange surfaces in the respiratory system is accurate?

    <p>They consist of simple squamous epithelium with a thin barrier.</p> Signup and view all the answers

    What is primarily responsible for moving mucus along the respiratory tract?

    <p>Ciliary beating</p> Signup and view all the answers

    What happens to the thoracic cavity during exhalation?

    <p>It decreases in volume</p> Signup and view all the answers

    Which pressure is greater during exhalation compared to atmospheric pressure?

    <p>Intrapulmonary pressure</p> Signup and view all the answers

    What is the primary reason air moves into the lungs during inhalation?

    <p>Negative intrapulmonary pressure</p> Signup and view all the answers

    Which physical change affects the volume of the lungs?

    <p>Change in intrapleural pressure</p> Signup and view all the answers

    What defines the direction of airflow in the respiratory tract?

    <p>Differences between atmospheric pressure and intrapulmonary pressure</p> Signup and view all the answers

    What is tidal volume?

    <p>The volume of air moved in a normal breath</p> Signup and view all the answers

    What occurs when intrapulmonary pressure is greater than atmospheric pressure?

    <p>Exhalation occurs</p> Signup and view all the answers

    What principle explains the inverse relationship between pressure and volume in gases?

    <p>Boyle's Law</p> Signup and view all the answers

    Which of the following influences the intrapulmonary pressure during breathing?

    <p>Changes in thoracic cavity volume</p> Signup and view all the answers

    During which phase of breathing is the thoracic cavity volume increased?

    <p>Inhalation</p> Signup and view all the answers

    What happens to alveolar PO2 and PCO2 levels when tissue oxygen demand increases and respiratory rate does not change?

    <p>Alveolar PO2 levels decrease and PCO2 levels increase.</p> Signup and view all the answers

    Which of the following is NOT a factor influencing lung compliance?

    <p>Presence of pulmonary surfactant</p> Signup and view all the answers

    What occurs when there is an increase in both tissue oxygen demand and carbon dioxide levels?

    <p>Respiratory rate and tidal volume must increase.</p> Signup and view all the answers

    How does increased resistance in the lungs affect energy demand during pulmonary ventilation?

    <p>It increases the muscular effort required.</p> Signup and view all the answers

    What does PCO2 represent in the context of respiratory gas equilibrium?

    <p>Partial pressure of carbon dioxide in blood</p> Signup and view all the answers

    What result may occur due to unaddressed hypoxia from decreased alveolar PO2 levels?

    <p>Dangerous drop in blood pH</p> Signup and view all the answers

    Which aspect of pulmonary ventilation is primarily influenced by muscular activity?

    <p>Change in intrapulmonary pressure</p> Signup and view all the answers

    Which of the following indicates the difficulty of inflating or deflating the lungs?

    <p>Lung compliance</p> Signup and view all the answers

    What condition results from an inability to effectively increase tidal volume during increased respiratory demand?

    <p>Alveolar hypoventilation</p> Signup and view all the answers

    Which of the following is NOT classified as a chronic obstructive pulmonary disease (COPD)?

    <p>Asthma</p> Signup and view all the answers

    What does the resistance of the lungs indicate during ventilation?

    <p>The force required to inflate or deflate the lungs</p> Signup and view all the answers

    What is the primary function of the dorsal respiratory group (DRG)?

    <p>Regulate inspiration through sensory input</p> Signup and view all the answers

    How does the ventral respiratory group (VRG) primarily function?

    <p>It activates only during increased breathing demands.</p> Signup and view all the answers

    What is a key role of chemoreceptors in the respiratory control system?

    <p>Monitor O2, CO2, and pH levels in blood</p> Signup and view all the answers

    Which center is responsible for generating the rhythmic pattern of breathing?

    <p>Pre-Bӧtzinger complex</p> Signup and view all the answers

    Which of the following best contrasts chronic bronchitis and emphysema?

    <p>Chronic bronchitis is characterized by mucus production, whereas emphysema involves alveolar damage.</p> Signup and view all the answers

    What is indicated by the compliance of the lungs?

    <p>The lungs' ability to stretch and expand</p> Signup and view all the answers

    What is a common symptom experienced by patients with COPD due to airflow limitation?

    <p>Persistent cough with mucus</p> Signup and view all the answers

    Which mechanism is primarily responsible for controlling respiratory rhythm?

    <p>Responses from chemoreceptors and baroreceptors</p> Signup and view all the answers

    What does the term 'resistance' refer to in the context of respiratory physiology?

    <p>The ease of airflow through the airways</p> Signup and view all the answers

    What is the main function of the inflation reflex in respiration?

    <p>To prevent overexpansion of the lungs</p> Signup and view all the answers

    What initiates the deflation reflex in the respiratory system?

    <p>Stretch receptors in the lungs during deflation</p> Signup and view all the answers

    What type of reflex is characterized by coughing and sneezing when the airways are exposed to irritants?

    <p>Protective reflex</p> Signup and view all the answers

    How does aging affect respiratory function according to the given information?

    <p>It decreases all aspects of respiratory function</p> Signup and view all the answers

    Which of the following conditions is mentioned as a normal change in respiratory function for individuals over age 50?

    <p>Development of emphysema</p> Signup and view all the answers

    What are the paranasal sinuses responsible for?

    <p>Moistening and cleaning nasal cavity surfaces</p> Signup and view all the answers

    Which sinus is located in the forehead?

    <p>Frontal sinus</p> Signup and view all the answers

    What best describes the function of the lamina propria in the nasal cavity?

    <p>It warms and humidifies inhaled air</p> Signup and view all the answers

    What is the function of the nasal vestibule?

    <p>Filtering airborne particles</p> Signup and view all the answers

    Which part of the pharynx is linked to the digestive system?

    <p>Oropharynx</p> Signup and view all the answers

    What separates the nasal cavity from the oral cavity?

    <p>Hard palate</p> Signup and view all the answers

    What is the primary function of the larynx?

    <p>Protecting the glottis and producing sound</p> Signup and view all the answers

    What is a consequence of mouth breathing compared to nasal breathing?

    <p>It increases heat and water loss</p> Signup and view all the answers

    What percentage of carbon dioxide is transported dissolved in plasma?

    <p>7 percent</p> Signup and view all the answers

    What compound is formed when carbon dioxide binds to hemoglobin?

    <p>Carbaminohemoglobin</p> Signup and view all the answers

    What is the main method by which carbon dioxide is transported in the blood?

    <p>Converted to bicarbonate</p> Signup and view all the answers

    What enzyme catalyzes the conversion of carbon dioxide and water to carbonic acid?

    <p>Carbonic anhydrase</p> Signup and view all the answers

    What ion primarily exchanges with bicarbonate ions during the chloride shift?

    <p>Chloride ion (Cl–)</p> Signup and view all the answers

    Which of the following is NOT a method of carbon dioxide transport in the bloodstream?

    <p>Converted to nitrous oxide</p> Signup and view all the answers

    What happens to carbonic acid after its formation in the blood?

    <p>It dissociates into bicarbonate and hydrogen ions</p> Signup and view all the answers

    What role does hemoglobin play in the context of carbon dioxide transport?

    <p>It acts as a carrier for carbon dioxide</p> Signup and view all the answers

    Which process allows bicarbonate ions to exit red blood cells?

    <p>Chloride shift</p> Signup and view all the answers

    What percentage of carbon dioxide is bound to hemoglobin in red blood cells?

    <p>23 percent</p> Signup and view all the answers

    How does inhaled air change as it travels through the respiratory tract?

    <p>It gets moistened and warmed.</p> Signup and view all the answers

    What is the effect of diffusion between the alveolar mixture and pulmonary capillaries?

    <p>Increases blood PO2 and decreases PCO2.</p> Signup and view all the answers

    What does Henry's law state about gas in solution?

    <p>It is directly proportional to the partial pressure.</p> Signup and view all the answers

    What happens to oxygen as blood leaves the lungs and enters the systemic circulation?

    <p>PO2 drops slightly due to mixing with deoxygenated blood.</p> Signup and view all the answers

    What drives the diffusion of gases during internal respiration?

    <p>Higher PCO2 in tissues than in blood.</p> Signup and view all the answers

    What causes the variation in partial pressures of gases in the respiratory tract?

    <p>The gas mixture varies by location within the respiratory tract.</p> Signup and view all the answers

    What mixed with exhaled air in dead space affects its composition?

    <p>Air from the alveoli.</p> Signup and view all the answers

    Which process occurs as blood arrives in the pulmonary arteries?

    <p>It has lower PO2 and higher PCO2.</p> Signup and view all the answers

    What factors influence the movement of oxygen from blood into interstitial fluid?

    <p>High blood oxygen and low tissue oxygen levels.</p> Signup and view all the answers

    How does Boyle's law describe the relationship between pressure and volume?

    <p>Pressure decreases when volume increases.</p> Signup and view all the answers

    What happens to the pressure inside the thoracic cavity during inhalation?

    <p>It decreases as thoracic volume increases.</p> Signup and view all the answers

    What occurs when air enters the pleural cavity?

    <p>The lungs collapse (atelectasis).</p> Signup and view all the answers

    What initiates the movement of air into the lungs during inhalation?

    <p>Pressure outside the thorax is higher than inside.</p> Signup and view all the answers

    Which action leads to the expansion of the thoracic cavity?

    <p>Contraction of the diaphragm.</p> Signup and view all the answers

    What directly influences the pressure changes that enable pulmonary ventilation?

    <p>Movements of the diaphragm and rib cage.</p> Signup and view all the answers

    During the start of a breath, what is true about the pressures inside and outside the thorax?

    <p>Pressures are identical, causing no air movement.</p> Signup and view all the answers

    What occurs as a result of decreasing the volume of a gas container?

    <p>Pressure increases.</p> Signup and view all the answers

    What factor is responsible for creating a bond between the parietal and visceral pleurae?

    <p>Pleural fluid.</p> Signup and view all the answers

    What happens to lung pressure when thoracic cavity volume decreases?

    <p>Air is expelled due to increased pressure.</p> Signup and view all the answers

    What type of epithelium lines the nasal cavity and superior pharynx?

    <p>Pseudostratified ciliated columnar epithelium</p> Signup and view all the answers

    What main mechanism is involved in moving mucus and trapped debris in the respiratory system?

    <p>Mucociliary escalator</p> Signup and view all the answers

    What is the distance between air and blood in the capillaries during gas exchange?

    <p>Less than 1 µm</p> Signup and view all the answers

    What is the primary function of the apneustic centers?

    <p>Promote inhalation by stimulating the DRG</p> Signup and view all the answers

    Which part of the respiratory tract has stratified squamous epithelium?

    <p>Inferior portions of the pharynx</p> Signup and view all the answers

    How do pneumotaxic centers affect breathing rate?

    <p>Increased output shortens inhalation duration.</p> Signup and view all the answers

    What is the role of epithelial stem cells in the respiratory tract?

    <p>Replace damaged or old cells</p> Signup and view all the answers

    What role do higher centers have in respiratory control?

    <p>They can alter the activity of pneumotaxic centers.</p> Signup and view all the answers

    What does the lamina propria in the respiratory mucosa contain?

    <p>Mucous glands</p> Signup and view all the answers

    What characterizes the mucociliary escalator in the respiratory system?

    <p>Flow of mucus towards the pharynx</p> Signup and view all the answers

    What type of information do apneustic centers use to adjust stimulation levels?

    <p>Sensory information from the vagus nerve about lung inflation</p> Signup and view all the answers

    What is the overall effect of decreased output from pneumotaxic centers?

    <p>Decreased respiratory rate and increased depth of respiration</p> Signup and view all the answers

    Which structure forms the gas exchange surfaces in the lungs?

    <p>Alveoli</p> Signup and view all the answers

    What is the hemoglobin saturation percentage in blood leaving the body tissues?

    <p>75 percent</p> Signup and view all the answers

    How does a decrease in blood pH affect hemoglobin saturation?

    <p>Shifts the saturation curve to the right</p> Signup and view all the answers

    What physiological change occurs due to higher temperatures in active tissues?

    <p>Hemoglobin releases oxygen more readily</p> Signup and view all the answers

    What effect does 2,3-bisphosphoglycerate (BPG) have on hemoglobin's oxygen release?

    <p>Increases oxygen release</p> Signup and view all the answers

    What happens to BPG production as red blood cells age?

    <p>BPG production declines</p> Signup and view all the answers

    What is the approximate saturation of hemoglobin in blood found in active muscles?

    <p>20 percent</p> Signup and view all the answers

    What concept explains the direct relationship between blood pH and hemoglobin saturation?

    <p>Bohr effect</p> Signup and view all the answers

    What is the typical partial pressure of oxygen (PO2) in blood entering the systemic circuit?

    <p>95 mm Hg</p> Signup and view all the answers

    What primarily regulates the hemoglobin saturation curve?

    <p>All of the above</p> Signup and view all the answers

    In which situation is hemoglobin least saturated with oxygen?

    <p>In blood from active muscle</p> Signup and view all the answers

    What is the primary function of the mucus secreted by the paranasal sinuses?

    <p>To moisturize and clean the nasal cavity surfaces</p> Signup and view all the answers

    Which structure separates the nasal and oral cavities?

    <p>Nasal septum</p> Signup and view all the answers

    What is the role of the extensive network of veins in the lamina propria of the nasal cavity?

    <p>To release heat for warming inhaled air</p> Signup and view all the answers

    What kind of epithelium lines the oropharynx?

    <p>Stratified squamous epithelium</p> Signup and view all the answers

    Which part of the pharynx is associated with the auditory tube?

    <p>Nasopharynx</p> Signup and view all the answers

    What benefit is lost when breathing through the mouth instead of the nose?

    <p>Moisturizing and warming of inhaled air</p> Signup and view all the answers

    What forms the floor of the nasal cavity?

    <p>Hard palate</p> Signup and view all the answers

    What is the glottis?

    <p>The opening into the larynx</p> Signup and view all the answers

    During exhalation, what happens to the mucosa in the nasal cavity?

    <p>It absorbs heat and water from exhaled air</p> Signup and view all the answers

    Which of the following sinuses is not part of the paranasal sinuses?

    <p>Temporal sinus</p> Signup and view all the answers

    What happens to the pressure inside a container when its volume decreases?

    <p>Pressure increases</p> Signup and view all the answers

    What initiates airflow into the lungs during inhalation?

    <p>Decreased pressure inside the thoracic cavity</p> Signup and view all the answers

    What is the consequence when air enters the pleural cavity?

    <p>The bond between pleura is broken, leading to lung collapse</p> Signup and view all the answers

    Which law explains the relationship between gas volume and pressure?

    <p>Boyle's law</p> Signup and view all the answers

    How does the diaphragm affect lung volume during breathing?

    <p>It flattens to increase lung volume</p> Signup and view all the answers

    Which statement accurately describes airflow during inhalation?

    <p>Air flows from high pressure to low pressure</p> Signup and view all the answers

    What happens to the number of molecular collisions in a gas when the volume of its container increases?

    <p>Collisions decrease</p> Signup and view all the answers

    What is the function of pleural fluid between the pleura layers?

    <p>It forms a bond between pleura layers</p> Signup and view all the answers

    Which action occurs when the thoracic cavity enlarges?

    <p>Decreased pressure inside the cavity</p> Signup and view all the answers

    What is the state of pressure inside and outside the thorax at the start of a breath?

    <p>Identical pressure inside and outside</p> Signup and view all the answers

    What function do pneumotaxic centers serve in respiratory control?

    <p>They stimulate exhalation and can adjust respiratory rate.</p> Signup and view all the answers

    How do apneustic centers regulate respiration?

    <p>By adjusting the duration of inhalation based on lung inflation.</p> Signup and view all the answers

    What determines the pace of respiration during quiet breathing?

    <p>The combined influence of pneumotaxic and apneustic centers.</p> Signup and view all the answers

    Which statement accurately describes the relationship between pneumotaxic output and inhalation duration?

    <p>Altered pneumotaxic output can shorten inhalation duration.</p> Signup and view all the answers

    What role do higher centers in the brain play in respiratory control?

    <p>They can enhance the output of pneumotaxic centers but are not essential for normal breathing.</p> Signup and view all the answers

    What is the primary reason cystic fibrosis is considered a lethal inherited disease?

    <p>It causes thick mucus that obstructs the respiratory tract.</p> Signup and view all the answers

    Which physical characteristic is associated with cystic fibrosis that impacts lung function?

    <p>Excessive mucus production.</p> Signup and view all the answers

    Which anatomical structure is incorrect in its function within the nasal cavity?

    <p>Nasal cartilages provide rigidity to enhance airflow.</p> Signup and view all the answers

    What is the average lifespan of individuals with cystic fibrosis who reach adulthood?

    <p>37 years</p> Signup and view all the answers

    What is the role of the mucociliary escalator compromised in patients with cystic fibrosis?

    <p>Transporting foreign particles out of the respiratory tract.</p> Signup and view all the answers

    What is the primary function of the structures within the nasal cavity?

    <p>To filter, warm, and humidify incoming air.</p> Signup and view all the answers

    What common bacterial infection is associated with cystic fibrosis?

    <p>Pseudomonas aeruginosa</p> Signup and view all the answers

    Which of the following best describes a potential cause of death in individuals with cystic fibrosis?

    <p>Heart failure combined with chronic lung infection.</p> Signup and view all the answers

    What happens to the partial pressures of gases as inhaled air enters the alveoli?

    <p>They vary based on the mixing with residual air.</p> Signup and view all the answers

    How does Henry's law relate to gas exchange during respiration?

    <p>It helps explain the solubility of carbon dioxide in blood plasma.</p> Signup and view all the answers

    What primarily influences the change in PO2 of blood from pulmonary veins to peripheral capillaries?

    <p>The mixing of blood with oxygen-depleted blood from tissues.</p> Signup and view all the answers

    During external respiration, which gas is primarily exchanged in the alveoli?

    <p>Oxygen enters blood while carbon dioxide exits into alveoli.</p> Signup and view all the answers

    What effect does exhaled air have on the air in the anatomical dead space?

    <p>It increases the partial pressure of the stale air.</p> Signup and view all the answers

    What is the result of oxygen diffusing into interstitial fluid during internal respiration?

    <p>It lowers the interstitial fluid's oxygen levels.</p> Signup and view all the answers

    What causes the difference in partial pressures of gases within the respiratory tract?

    <p>The previous breaths and dead space impact.</p> Signup and view all the answers

    Which statement about the gas mixture in the respiratory tract is true?

    <p>It varies significantly based on the respiratory phase and location.</p> Signup and view all the answers

    How do the partial pressures of oxygen and carbon dioxide typically differ in pulmonary arteries compared to alveolar air?

    <p>Lower oxygen and higher carbon dioxide in pulmonary arteries than alveoli.</p> Signup and view all the answers

    What is the primary consequence of increased resistance in the respiratory system?

    <p>Greater force needed for breathing</p> Signup and view all the answers

    What distinguishes emphysema from other forms of COPD?

    <p>Merging and expansion of alveoli</p> Signup and view all the answers

    Which of the following statements is true regarding chronic bronchitis?

    <p>It leads to frequent coughing and sputum production.</p> Signup and view all the answers

    Which term best describes individuals with asthma?

    <p>Intermittent responders</p> Signup and view all the answers

    What is a common cause of chronic bronchitis?

    <p>Cigarette smoking</p> Signup and view all the answers

    Which physiological change occurs in the airways during an asthma attack?

    <p>Constricting of smooth muscles</p> Signup and view all the answers

    What primary effect does emphysema have on the respiratory system?

    <p>Reduced effectiveness in oxygen absorption</p> Signup and view all the answers

    What is a characteristic symptom of COPD?

    <p>Persistent cough and sputum production</p> Signup and view all the answers

    What does increased compliance in the lungs typically lead to?

    <p>Increased ease of lung expansion</p> Signup and view all the answers

    Which of the following is a common trigger for asthma symptoms?

    <p>Cold air exposure</p> Signup and view all the answers

    What happens to hemoglobin saturation when blood pH decreases in active tissues?

    <p>Saturation decreases due to the Bohr effect</p> Signup and view all the answers

    Which factor leads to reduced oxygen release from hemoglobin in aged red blood cells?

    <p>Declining production of 2,3-bisphosphoglycerate (BPG)</p> Signup and view all the answers

    How does increased temperature affect hemoglobin's oxygen release?

    <p>It promotes more oxygen release from hemoglobin</p> Signup and view all the answers

    What is the primary oxygen saturation of hemoglobin in venous blood leaving body tissues?

    <p>75 percent</p> Signup and view all the answers

    What is a consequence of hemoglobin's affinity for oxygen decreasing due to 2,3-bisphosphoglycerate (BPG) levels?

    <p>Reduced oxygen release to tissues</p> Signup and view all the answers

    During exercise, which statement best describes oxygen delivery to active skeletal muscles?

    <p>Hemoglobin releases more oxygen to active muscles compared to rest</p> Signup and view all the answers

    What does a shift to the right in the oxygen-hemoglobin saturation curve indicate?

    <p>Decreased oxygen affinity of hemoglobin</p> Signup and view all the answers

    What is the primary partial pressure of oxygen (PO2) in hemoglobin within active muscle tissues?

    <p>15-20 mm Hg</p> Signup and view all the answers

    Which statement explains the physiological role of glycolysis in red blood cells?

    <p>It creates 2,3-bisphosphoglycerate (BPG) for oxygen release</p> Signup and view all the answers

    What is the primary function of the mucus secreted by the paranasal sinuses?

    <p>To moisten and clean nasal cavity surfaces</p> Signup and view all the answers

    Which part of the pharynx has the pharyngeal opening of the auditory tube?

    <p>Nasopharynx</p> Signup and view all the answers

    What happens to inhaled air as it passes through the nasal cavity?

    <p>It is warmed and humidified</p> Signup and view all the answers

    Which structural feature is responsible for the separation of the nasal and oral cavities?

    <p>Hard palate</p> Signup and view all the answers

    What role does the lamina propria of the nasal cavity predominantly serve?

    <p>To warm and humidify inhaled air</p> Signup and view all the answers

    What is the main consequence of mouth breathing in relation to the nasal cavity functions?

    <p>Elimination of heat and moisture retention benefits</p> Signup and view all the answers

    What anatomical structure forms the majority of the larynx?

    <p>Cartilage</p> Signup and view all the answers

    Which sinus is NOT included in the paranasal sinuses?

    <p>Temporal sinus</p> Signup and view all the answers

    Which of the following accurately characterizes the symptoms of asthma?

    <p>Symptoms are acute and intermittent with airway constriction.</p> Signup and view all the answers

    What primary change occurs in the lungs as a result of emphysema?

    <p>Destruction of alveolar walls leading to loss of surface area.</p> Signup and view all the answers

    Which group of individuals is specifically referred to as 'blue bloaters'?

    <p>Individuals with chronic bronchitis exhibiting cyanosis.</p> Signup and view all the answers

    What is the most significant effect of increased resistance in breathing for an individual with COPD?

    <p>Lower efficiency in ventilation and increased energy demand.</p> Signup and view all the answers

    Which condition is primarily indicated by overproduction of mucus and chronic cough?

    <p>Chronic bronchitis, due to inflammation of bronchial lining.</p> Signup and view all the answers

    What is the primary consequence of hypoxia on metabolic activities?

    <p>Severely limits metabolic activities</p> Signup and view all the answers

    Which term refers to the absence of oxygen supply to tissues?

    <p>Anoxia</p> Signup and view all the answers

    How does cigarette smoking primarily affect the respiratory system?

    <p>Causes chronic inflammation in the airways</p> Signup and view all the answers

    What is the primary role of external respiration?

    <p>Exchange of gases between blood, lungs, and external environment</p> Signup and view all the answers

    What typically occurs as a result of anoxia in tissues?

    <p>Localized damage due to lack of oxygen</p> Signup and view all the answers

    Which process occurs during internal respiration?

    <p>Absorption of oxygen from blood</p> Signup and view all the answers

    What occurs during pulmonary ventilation?

    <p>Movement of air in and out of the lungs</p> Signup and view all the answers

    Which physiological change is a common result of age in the respiratory system?

    <p>Decreased lung elasticity</p> Signup and view all the answers

    What is the impact of increased resistance during ventilation?

    <p>Increases energy demand for breathing</p> Signup and view all the answers

    Which of the following best describes 'compliance' in respiratory physiology?

    <p>Ease of lung expansion</p> Signup and view all the answers

    What effect does the contraction of the trachealis muscle have on airflow?

    <p>Narrows the trachea, restricting airflow</p> Signup and view all the answers

    Which statement describes the structure of bronchioles?

    <p>They lack cartilage and have thick smooth muscle.</p> Signup and view all the answers

    How does sympathetic stimulation affect the bronchioles?

    <p>Results in bronchodilation and increases airflow</p> Signup and view all the answers

    What happens to the diameter of bronchi as they branch into smaller tubes?

    <p>The diameter decreases with each successive branch.</p> Signup and view all the answers

    During an allergic reaction, which condition can occur in the bronchioles?

    <p>Bronchoconstriction leading to decreased airflow</p> Signup and view all the answers

    What is the role of the C-shaped tracheal cartilages?

    <p>Provide rigidity and allow for tracheal expansion during swallowing</p> Signup and view all the answers

    Which bronchioles are responsible for leading to the site of gas exchange?

    <p>Terminal bronchioles</p> Signup and view all the answers

    What characterizes the bronchi leading to the lungs?

    <p>Main bronchi are complete cartilage rings.</p> Signup and view all the answers

    What primarily regulates tracheal diameter changes?

    <p>Sympathetic stimulation</p> Signup and view all the answers

    What prevents the complete closure of the trachea during swallowing?

    <p>Incomplete posterior cartilages of the trachea</p> Signup and view all the answers

    What occurs to the thoracic cavity during exhalation?

    <p>Decreased volume of the cavity</p> Signup and view all the answers

    Which statement correctly describes the relationship between intrapulmonary pressure and atmospheric pressure during inhalation?

    <p>Intrapulmonary pressure is lower than atmospheric pressure</p> Signup and view all the answers

    Which factor primarily determines the direction of airflow during pulmonary ventilation?

    <p>Pressure difference between atmospheric and intrapulmonary pressures</p> Signup and view all the answers

    What is the definition of tidal volume in the context of breathing?

    <p>Volume of air exchanged during a single normal breath</p> Signup and view all the answers

    During exhalation, the relationship between intrapulmonary pressure and atmospheric pressure is characterized by which of the following?

    <p>Intrapulmonary pressure is greater than atmospheric pressure</p> Signup and view all the answers

    How does a decrease in thoracic cavity volume affect air pressure within the cavity during exhalation?

    <p>Increases intrapulmonary pressure</p> Signup and view all the answers

    In the context of Boyle's law, how does the volume of a gas relate to its pressure?

    <p>Pressure is inversely proportional to volume</p> Signup and view all the answers

    What primarily triggers airflow into the lungs during the inhalation process?

    <p>Negative intrapulmonary pressure relative to atmospheric pressure</p> Signup and view all the answers

    What is an accurate description of intrapulmonary pressure during normal breathing?

    <p>Varies with volume changes during inhalation and exhalation</p> Signup and view all the answers

    Which of the following processes occurs as air is forced out of the lungs during exhalation?

    <p>Air moves from higher intrapulmonary pressure to lower atmospheric pressure</p> Signup and view all the answers

    What percentage of lung cancer cases are attributed to cigarette smoking?

    <p>85–90 percent</p> Signup and view all the answers

    Which of the following changes occurs in the respiratory epithelium due to smoking?

    <p>Dysplasia followed by metaplasia</p> Signup and view all the answers

    What is the primary effect of metaplasia in the respiratory epithelium caused by irritants in smoke?

    <p>Replacement of respiratory epithelium with less effective tissue</p> Signup and view all the answers

    Which symptom is typically present when lung tumors restrict airflow or compress surrounding structures?

    <p>Shortness of breath</p> Signup and view all the answers

    How does smoking affect the function of cilia in the respiratory epithelium?

    <p>It causes cilia to become paralyzed, leading to mucus buildup.</p> Signup and view all the answers

    What is the main function of pneumocytes type II in the alveoli?

    <p>They produce surfactant to reduce surface tension.</p> Signup and view all the answers

    Which structure directly supplies a single pulmonary lobule with air?

    <p>Terminal bronchiole</p> Signup and view all the answers

    What comprises the pulmonary lobules and facilitates gas exchange?

    <p>Alveoli</p> Signup and view all the answers

    What is the purpose of the pleural fluid within the pleural cavity?

    <p>To reduce friction between the lung surfaces during respiration.</p> Signup and view all the answers

    What unique characteristic do the pulmonary alveoli contribute to the lungs?

    <p>They provide an open, spongy appearance due to their vast numbers.</p> Signup and view all the answers

    Which cell type in the alveolar epithelium is primarily responsible for gas diffusion?

    <p>Pneumocytes type I</p> Signup and view all the answers

    What is the role of elastic fibers surrounding the pulmonary alveoli?

    <p>To aid in the expansion and recoil of the lungs.</p> Signup and view all the answers

    What is found in the pleural cavity that contributes to lung function?

    <p>Pleural fluid</p> Signup and view all the answers

    What is a major function of the respiratory system beyond gas exchange?

    <p>Temperature regulation of the body</p> Signup and view all the answers

    How does the respiratory system protect its delicate exchange surfaces from external hazards?

    <p>By utilizing mechanical barriers such as cilia and mucus</p> Signup and view all the answers

    What structural feature of the respiratory system increases its surface area for gas exchange?

    <p>Alveolar sacs</p> Signup and view all the answers

    Which condition is characterized by the destruction of lung tissue and impaired gas exchange?

    <p>Emphysema</p> Signup and view all the answers

    What role does the upper respiratory system primarily serve?

    <p>Pathogen filtration and warming of air</p> Signup and view all the answers

    How is cystic fibrosis related to the function of the respiratory system?

    <p>It leads to thick mucus production that obstructs airways.</p> Signup and view all the answers

    What anatomical feature is primarily responsible for the movement of air in the lungs?

    <p>Diaphragm contraction</p> Signup and view all the answers

    What is a possible consequence of chronic inflammation in the airways?

    <p>Excess mucus production leading to blockages</p> Signup and view all the answers

    Which respiratory system structure plays a crucial role as an interface for air and blood?

    <p>Alveoli</p> Signup and view all the answers

    What is a primary method by which the respiratory system maintains homeostasis?

    <p>Adjusting the rate of ventilation based on carbon dioxide levels</p> Signup and view all the answers

    What causes air to be forced out of the lungs during exhalation?

    <p>Increased intrapulmonary pressure</p> Signup and view all the answers

    Which factor primarily determines the direction of airflow during pulmonary ventilation?

    <p>Difference between intrapulmonary pressure and atmospheric pressure</p> Signup and view all the answers

    What is the effect of decreased thoracic cavity volume during exhalation?

    <p>Increased intrapulmonary pressure</p> Signup and view all the answers

    How does the intrapulmonary pressure compare to atmospheric pressure during normal inhalation?

    <p>It is lower than atmospheric pressure</p> Signup and view all the answers

    What is tidal volume in the context of pulmonary ventilation?

    <p>Volume of air exchanged in normal inhalation and exhalation</p> Signup and view all the answers

    What role does the difference in atmospheric and intrapulmonary pressure play in breathing?

    <p>It determines the flow of air in and out of the lungs</p> Signup and view all the answers

    Which statement accurately describes pressure changes during pulmonary ventilation?

    <p>Intrapulmonary pressure increases during exhalation</p> Signup and view all the answers

    What occurs to the intrapulmonary pressure during normal breathing when the thoracic cavity expands?

    <p>It decreases, allowing air to flow in</p> Signup and view all the answers

    Which physical change affects lung volume the most during exhalation?

    <p>Relaxation of the diaphragm</p> Signup and view all the answers

    Which pressure is measured within the respiratory tract and usually at the alveoli?

    <p>Intrapulmonary pressure</p> Signup and view all the answers

    What is a primary consequence of cystic fibrosis affecting the respiratory system?

    <p>Reduced lifespan due to lung infections</p> Signup and view all the answers

    What role do the nasal conchae play in the respiratory system?

    <p>Swirling incoming air to trap particles</p> Signup and view all the answers

    Which of the following best explains why cystic fibrosis can become lethal?

    <p>It leads to heart failure and chronic lung infections</p> Signup and view all the answers

    How does the structure of the nose contribute to its function in the respiratory system?

    <p>The nasal cartilages keep nostrils open for airflow</p> Signup and view all the answers

    What would likely occur due to the dysfunction of the mucociliary escalator in individuals with cystic fibrosis?

    <p>Accumulation of pathogens in the lungs</p> Signup and view all the answers

    What is the average lifespan of adults with cystic fibrosis?

    <p>37 years</p> Signup and view all the answers

    Which feature of the nasal cavity is NOT accurately described?

    <p>Nose fully humidifies air before it reaches lungs</p> Signup and view all the answers

    What symptom is most commonly associated with chronic infections in cystic fibrosis?

    <p>Frequent wheezing</p> Signup and view all the answers

    What is the primary function of mucosa in the respiratory defense system?

    <p>To trap and clear debris and pathogens</p> Signup and view all the answers

    Which bacterium is notably associated with infections in individuals with cystic fibrosis?

    <p>Pseudomonas aeruginosa</p> Signup and view all the answers

    What is the primary physiological trigger for the increase in respiratory rate in response to hypercapnia?

    <p>An increase in arterial PCO2</p> Signup and view all the answers

    Which physiological condition most commonly results from hyperventilation?

    <p>Decreased arterial PCO2</p> Signup and view all the answers

    What response occurs when arterial blood pressure drops below normal levels?

    <p>Increased respiratory minute volume</p> Signup and view all the answers

    What is the major risk associated with hyperventilation during activities like swimming?

    <p>Loss of consciousness from oxygen starvation</p> Signup and view all the answers

    How does the body respond to a significant drop in arterial PCO2?

    <p>By stimulating chemoreceptors to decrease respiratory rate</p> Signup and view all the answers

    What role do surfactants produced by Pneumocytes type II play in the alveoli?

    <p>They reduce surface tension to prevent alveolar collapse.</p> Signup and view all the answers

    Which of the following statements accurately describes the structure of pulmonary lobules?

    <p>They contain alveoli and are supplied by terminal bronchioles.</p> Signup and view all the answers

    What distinguishes the visceral pleura from the parietal pleura?

    <p>Visceral pleura covers the outer surfaces of the lungs.</p> Signup and view all the answers

    Which of the following correctly describes the flow of air through the structures leading to alveoli?

    <p>Bronchioles → Terminal bronchiole → Alveolar ducts → Alveoli.</p> Signup and view all the answers

    What is the potential significance of the pleural cavity in lung function?

    <p>It holds pleural fluid that reduces friction during respiratory movements.</p> Signup and view all the answers

    How do elastic fibers surrounding the alveoli contribute to respiratory function?

    <p>They promote efficient air movement through recoil action.</p> Signup and view all the answers

    What feature of pulmonary alveoli primarily aids in efficient gas diffusion?

    <p>The large number of alveoli creating a vast surface area.</p> Signup and view all the answers

    What is a primary characteristic of respiratory bronchioles compared to terminal bronchioles?

    <p>They are more distal in the bronchial tree.</p> Signup and view all the answers

    What is the primary function of the apneustic centers in the pons?

    <p>Promote inhalation</p> Signup and view all the answers

    How do pneumotaxic centers affect inhalation duration?

    <p>They shorten inhalation duration</p> Signup and view all the answers

    Which statement accurately describes the higher centers in respiratory control?

    <p>They can alter the activity of pneumotaxic centers</p> Signup and view all the answers

    What sensory information influences the apneustic centers' stimulation levels?

    <p>Lung inflation status</p> Signup and view all the answers

    Which of the following best describes the function of pneumotaxic centers when activated?

    <p>Increase respiratory rate</p> Signup and view all the answers

    What role do the paired nuclei in the pons play in respiration?

    <p>They adjust the output of respiratory rhythmicity centers</p> Signup and view all the answers

    What happens to the rate and depth of respiration when pneumotaxic output is decreased?

    <p>Rate decreases while depth increases</p> Signup and view all the answers

    What type of breathing can occur independently of input from higher centers?

    <p>Quiet breathing</p> Signup and view all the answers

    Which center is responsible for inhibiting the apneustic centers?

    <p>Pneumotaxic centers</p> Signup and view all the answers

    What is the result of increased stimulation from the apneustic centers?

    <p>Increased inhalation duration</p> Signup and view all the answers

    What is the primary role of the epiglottis during swallowing?

    <p>To protect the glottis from food and liquids.</p> Signup and view all the answers

    Which cartilage is known as the Adam's apple?

    <p>Thyroid cartilage</p> Signup and view all the answers

    Which of the following statements is true regarding cricoid cartilage?

    <p>It creates a complete ring around the larynx.</p> Signup and view all the answers

    What is the function of arytenoid cartilages?

    <p>To open and close the glottis during sound production.</p> Signup and view all the answers

    Which cartilage articulates with the superior surface of cricoid cartilage?

    <p>Arytenoid cartilage</p> Signup and view all the answers

    What is true about the thyroid cartilage's attachment?

    <p>Thyrohyoid ligament connects it to the hyoid bone.</p> Signup and view all the answers

    Which paired cartilage assists in the function of the arytenoid cartilages?

    <p>Corniculate cartilage</p> Signup and view all the answers

    What shape best describes the cricoid cartilage?

    <p>Ring-shaped</p> Signup and view all the answers

    What does the term 'laryngeal prominence' refer to?

    <p>The visible protrusion of the thyroid cartilage.</p> Signup and view all the answers

    How does swallowing affect the position of the larynx?

    <p>It elevates the larynx.</p> Signup and view all the answers

    What is the primary role of the trachealis muscle in the structure of the trachea?

    <p>To contract and narrow the trachea for airflow regulation</p> Signup and view all the answers

    How does sympathetic stimulation affect bronchiolar diameter?

    <p>It causes bronchodilation, increasing airflow</p> Signup and view all the answers

    Why are the tracheal cartilages incomplete posteriorly?

    <p>To enable the expansion of the esophagus during swallowing</p> Signup and view all the answers

    What physiological reaction is primarily responsible for extreme bronchoconstriction during an allergic response like asthma?

    <p>Parasympathetic nervous system activation</p> Signup and view all the answers

    Which of the following bronchi types would have complete cartilage rings?

    <p>Main bronchi</p> Signup and view all the answers

    What effects do terminal bronchioles have in relation to gas exchange?

    <p>They lead to pulmonary lobules where gas exchange occurs</p> Signup and view all the answers

    As bronchioles branch into smaller tubes, what happens to their diameter?

    <p>The diameter decreases with each branch</p> Signup and view all the answers

    What happens to airflow as the bronchioles undergo bronchoconstriction?

    <p>Airflow decreases</p> Signup and view all the answers

    During physical activity, what is the expected response of the trachea due to sympathetic stimulation?

    <p>Widening to enhance airflow</p> Signup and view all the answers

    What characterizes respiratory bronchioles in the context of the bronchiolar tree?

    <p>They are the last division before gas exchange occurs</p> Signup and view all the answers

    Which of the following is NOT a component of the respiratory rhythmicity centers in the brainstem?

    <p>Apneustic center</p> Signup and view all the answers

    Which statement accurately describes the function of the dorsal respiratory group (DRG)?

    <p>Varies response based on input from chemoreceptors and baroreceptors.</p> Signup and view all the answers

    In which situation does the ventral respiratory group (VRG) predominantly function?

    <p>During heightened respiratory needs involving accessory muscles.</p> Signup and view all the answers

    How do chemoreceptors in the DRG regulate respiratory function?

    <p>By detecting levels of oxygen, carbon dioxide, and pH in the blood.</p> Signup and view all the answers

    What is a key characteristic of chronic bronchitis as it relates to airways?

    <p>Excessive mucus production resulting in airway obstruction.</p> Signup and view all the answers

    What is the effect of trachealis contraction on airflow through the trachea?

    <p>It narrows the trachea and restricts airflow.</p> Signup and view all the answers

    What role do C-shaped tracheal cartilages play during swallowing?

    <p>They permit expansion of the trachea.</p> Signup and view all the answers

    Which nervous system activity results in bronchodilation in the bronchioles?

    <p>Increased sympathetic activity.</p> Signup and view all the answers

    During an allergic reaction, which condition can occur in the bronchioles?

    <p>Extreme bronchoconstriction.</p> Signup and view all the answers

    What is the primary function of the terminal bronchioles?

    <p>Gas exchange.</p> Signup and view all the answers

    What happens to the diameter of the bronchi as they branch further?

    <p>It decreases with each new branch.</p> Signup and view all the answers

    How many lobar bronchi are there in the right lung?

    <p>Three.</p> Signup and view all the answers

    Which of the following best describes the respiratory bronchioles?

    <p>They are the last division before pulmonary lobules.</p> Signup and view all the answers

    What primarily contributes to passive exhalation during quiet breathing?

    <p>Elastic recoil of lung tissues and gravity</p> Signup and view all the answers

    Which muscle is responsible for approximately 75% of the movement during inhalation?

    <p>Diaphragm</p> Signup and view all the answers

    Which of the following is NOT considered a primary inspiratory muscle?

    <p>Serratus anterior</p> Signup and view all the answers

    Which of these muscles assists in increasing the amount of air moved during inspiration when oxygen demands are high?

    <p>Sternocleidomastoid</p> Signup and view all the answers

    How are expiratory muscles activated during exhalation?

    <p>When active forceful exhalation is required</p> Signup and view all the answers

    What role does gravity play during exhalation?

    <p>Assists in elastic recoil of lungs</p> Signup and view all the answers

    Which statement about accessory respiratory muscles is correct?

    <p>They assist primary inspiratory muscles.</p> Signup and view all the answers

    Which factors influence respiratory minute volume?

    <p>Respiratory rate and tidal volume</p> Signup and view all the answers

    What distinguishes primary muscle action from accessory muscle action during breathing?

    <p>Primary muscles handle normal breathing while accessory muscles assist during increased effort.</p> Signup and view all the answers

    Which of the following muscles is NOT categorized as an accessory inspiratory muscle?

    <p>Internal obliques</p> Signup and view all the answers

    What does anatomical dead space refer to?

    <p>Air remaining in the conducting portion of the lungs</p> Signup and view all the answers

    How is alveolar ventilation calculated?

    <p>Breaths per minute multiplied by (tidal volume minus anatomic dead space)</p> Signup and view all the answers

    What is true regarding the primary expiratory muscles?

    <p>There are no designated primary expiratory muscles.</p> Signup and view all the answers

    Which breathing pattern is more effective for ventilating alveoli?

    <p>Slow, deep breaths</p> Signup and view all the answers

    What is Boyle’s law related to in respiratory physiology?

    <p>Direction of air movement during pulmonary ventilation</p> Signup and view all the answers

    What does partial pressure represent in a gas mixture?

    <p>Pressure exerted by a single gas in the mixture</p> Signup and view all the answers

    According to Dalton’s law, what happens to the total pressure of a gas mixture?

    <p>It equals the sum of all partial pressures</p> Signup and view all the answers

    What happens to tidal volume when the demand for oxygen increases?

    <p>It must be increased</p> Signup and view all the answers

    What are the two components needed to calculate alveolar ventilation?

    <p>Respiratory rate and tidal volume</p> Signup and view all the answers

    How is the volume of air in the alveoli defined?

    <p>Tidal volume without dead space</p> Signup and view all the answers

    What happens to the partial pressure of oxygen (PO2) in blood arriving in the pulmonary arteries compared to that in alveolar air?

    <p>It is lower than in alveolar air</p> Signup and view all the answers

    Which law states that the amount of a particular gas in solution is proportional to its partial pressure at a constant temperature?

    <p>Henry's law</p> Signup and view all the answers

    During diffusion in external respiration, what occurs to blood PCO2?

    <p>It decreases as carbon dioxide leaves</p> Signup and view all the answers

    What effect does mixing with blood from capillaries around conducting passageways have on PO2 of blood leaving the lungs?

    <p>It causes a slight decrease in PO2</p> Signup and view all the answers

    How does inhaled air change as it travels down the respiratory tract?

    <p>It gets moistened and warmed</p> Signup and view all the answers

    In internal respiration, where does oxygen primarily diffuse from?

    <p>From blood to interstitial fluid</p> Signup and view all the answers

    What is the consequence of carbon dioxide levels being higher in tissues than in blood?

    <p>Carbon dioxide leaves the blood into the tissues</p> Signup and view all the answers

    What is the primary effect of gas mixture variation on respiratory function?

    <p>It alters the partial pressures of component gases</p> Signup and view all the answers

    What happens to oxygen levels in the blood during diffusion at the alveoli?

    <p>Oxygen enters the blood, increasing levels</p> Signup and view all the answers

    What characterizes the gas exchange process during pulmonary ventilation?

    <p>Partial pressures of component gases vary by location</p> Signup and view all the answers

    What is the most significant factor influencing respiration under normal conditions?

    <p>PCO2</p> Signup and view all the answers

    What is the primary cause of hypercapnia?

    <p>Hypoventilation</p> Signup and view all the answers

    What occurs in response to hypocapnia?

    <p>Decrease in respiratory rate</p> Signup and view all the answers

    Which of the following accurately describes the primary functions of the respiratory system?

    <p>Facilitating gas exchange</p> Signup and view all the answers

    What triggers the respiratory centers when blood pressure drops below normal?

    <p>Baroreceptors stimulation</p> Signup and view all the answers

    How are the delicate respiratory surfaces protected from pathogens and debris?

    <p>Through the action of cilia and mucus</p> Signup and view all the answers

    What is a characteristic feature of cystic fibrosis?

    <p>Excessive mucus accumulation</p> Signup and view all the answers

    What can happen if a swimmer hyperventilates too much?

    <p>Loss of consciousness from oxygen starvation</p> Signup and view all the answers

    Which organ is NOT part of the upper respiratory system?

    <p>Trachea</p> Signup and view all the answers

    What role do the organs of the upper respiratory system play?

    <p>Warming and humidifying air</p> Signup and view all the answers

    Which structure is essential for protecting the lungs from external hazards?

    <p>Cilia</p> Signup and view all the answers

    What major result occurs from the respiratory exchange surfaces being delicate?

    <p>Higher risk of infection</p> Signup and view all the answers

    Which of the following processes is NOT a function of the respiratory system?

    <p>Nutrient absorption</p> Signup and view all the answers

    How does Boyle's law describe the relationship between pressure and volume in a gas?

    <p>Pressure is inversely related to volume.</p> Signup and view all the answers

    What occurs in the thoracic cavity during inhalation?

    <p>Volume increases and pressure decreases.</p> Signup and view all the answers

    What happens when air enters the pleural cavity?

    <p>Atelectasis or lung collapse occurs.</p> Signup and view all the answers

    Why do air molecules flow into the lungs during inhalation?

    <p>Pressure outside is greater than inside the thorax.</p> Signup and view all the answers

    What percentage of oxygen in blood is bound to hemoglobin?

    <p>98.5 percent</p> Signup and view all the answers

    How many molecules of oxygen can each hemoglobin molecule bind?

    <p>Four</p> Signup and view all the answers

    What effect does decreasing the thoracic cavity's volume have on lung pressure?

    <p>It causes an increase in lung pressure.</p> Signup and view all the answers

    What is the direct consequence of increasing the volume of the thoracic cavity?

    <p>Decrease in air pressure inside the cavity.</p> Signup and view all the answers

    What is the primary danger of carbon monoxide regarding oxygen transport?

    <p>It binds to heme units, making them unavailable for oxygen transport</p> Signup and view all the answers

    What does the oxygen-hemoglobin saturation curve illustrate?

    <p>Hemoglobin's affinity for oxygen at different partial pressures</p> Signup and view all the answers

    What describes the movement of gas molecules when volume is decreased in a container?

    <p>Molecules collide more frequently, increasing pressure.</p> Signup and view all the answers

    What role do the diaphragm and rib cage play in pulmonary ventilation?

    <p>They change the volume of the thoracic cavity.</p> Signup and view all the answers

    What is hemoglobin saturation?

    <p>The percentage of heme units containing bound oxygen at any moment</p> Signup and view all the answers

    At what partial pressure of oxygen (PO2) is hemoglobin typically over 90 percent saturated?

    <p>60 mm Hg</p> Signup and view all the answers

    What is a consequence of increased volume in the lungs during inhalation?

    <p>Creation of negative pressure relative to atmospheric pressure.</p> Signup and view all the answers

    What happens to the pressure differential when the thoracic cavity compresses?

    <p>Pressure inside increases rapidly.</p> Signup and view all the answers

    How much oxygen is typically dissolved in the plasma per 100 mL of blood?

    <p>0.3 mL</p> Signup and view all the answers

    Which component of hemoglobin is responsible for binding oxygen?

    <p>Iron ions in heme units</p> Signup and view all the answers

    Which muscles are primarily responsible for inhalation?

    <p>Diaphragm and External intercostals</p> Signup and view all the answers

    What happens to hemoglobin's affinity for oxygen when more oxygen molecules bind to it?

    <p>It increases</p> Signup and view all the answers

    What characterizes quiet breathing?

    <p>Active inhalation and passive exhalation</p> Signup and view all the answers

    How much oxygen is transported in blood leaving the alveoli?

    <p>20 mL</p> Signup and view all the answers

    Which of the following muscles is considered an accessory inspiratory muscle?

    <p>Serratus anterior</p> Signup and view all the answers

    How is exhalation typically facilitated during quiet breathing?

    <p>Elastic recoil of lung tissues and gravity</p> Signup and view all the answers

    What percentage of inhalation movement is attributed to the diaphragm?

    <p>75 percent</p> Signup and view all the answers

    What is the role of accessory respiratory muscles?

    <p>To assist with active inhalation or provide forceful exhalation</p> Signup and view all the answers

    Which statement is true regarding primary expiratory muscles?

    <p>There are no primary expiratory muscles.</p> Signup and view all the answers

    What happens to the thoracic cavity during the contraction of the diaphragm?

    <p>Increases in volume</p> Signup and view all the answers

    Which of the following statements about exhalation is correct?

    <p>It can be enhanced by the use of expiratory muscles.</p> Signup and view all the answers

    In what situation would accessory inspiratory muscles be primarily used?

    <p>When oxygen demand exceeds primary muscle capacity</p> Signup and view all the answers

    Study Notes

    Lung Function

    • The lungs remove carbon dioxide, a waste product of metabolism, from the body through exhalation.
    • The lungs replenish the body with fresh oxygen through inhalation.
    • Oxygen is transported to red blood cells in the lungs.

    Heart-Lung Interaction

    • The heart and lungs work together for gas exchange.
    • The heart pumps unoxygenated blood to the lungs through the pulmonary artery.
    • The lungs oxygenate the blood, which is then returned to the heart through the pulmonary vein.
    • The heart pumps oxygenated blood to the body through the aorta.

    Lung Anatomy

    • Air enters the body through the nose and mouth, traveling through the upper respiratory system.
    • The upper respiratory system includes the nasal cavities, pharynx, larynx, thyroid cartilage, and cricoid cartilage.
    • Air travels down the lower respiratory system, including the trachea and bronchi.
    • The trachea branches into the right and left primary bronchi at the carina.
    • The bronchi enter the lungs at the hilum, along with pulmonary arteries and veins.
    • The primary bronchi further branch into lobar bronchi (secondary bronchi), then into segmental bronchi (tertiary bronchi).
    • Bronchioles connect to the alveolar sacs through alveolar ducts.
    • Alveolar sacs contain alveoli, the site of gas exchange.

    Lung Lobes

    • The right lung has three lobes: upper, middle, and lower.
    • The left lung has two lobes: upper and lower.

    Lung Layers

    • The lungs have two layers: the visceral layer and the parietal layer.
    • Serous fluid between the layers allows the lungs to glide smoothly during breathing.

    Inhalation and Exhalation

    • The diaphragm contracts during inhalation, creating negative pressure in the chest cavity and drawing air into the lungs.
    • The diaphragm relaxes during exhalation, creating positive pressure in the lungs and forcing air out.
    • Gas exchange occurs within the alveoli, where oxygen enters the bloodstream and carbon dioxide leaves.

    Microscopic Gas Exchange

    • Capillaries surrounding the alveoli receive unoxygenated blood from the pulmonary artery.
    • Carbon dioxide diffuses from the blood into the alveoli to be exhaled.
    • Oxygen diffuses from the alveoli into the blood, attaching to red blood cells.
    • Oxygenated blood is returned to the heart through the pulmonary vein.

    Lung Function

    • The lungs remove carbon dioxide, a waste product of metabolism, from the body through exhalation.
    • The lungs replenish the body with fresh oxygen through inhalation.
    • Oxygen is transported to red blood cells in the lungs.

    Heart-Lung Interaction

    • The heart and lungs work together for gas exchange.
    • The heart pumps unoxygenated blood to the lungs through the pulmonary artery.
    • The lungs oxygenate the blood, which is then returned to the heart through the pulmonary vein.
    • The heart pumps oxygenated blood to the body through the aorta.

    Lung Anatomy

    • Air enters the body through the nose and mouth, traveling through the upper respiratory system.
    • The upper respiratory system includes the nasal cavities, pharynx, larynx, thyroid cartilage, and cricoid cartilage.
    • Air travels down the lower respiratory system, including the trachea and bronchi.
    • The trachea branches into the right and left primary bronchi at the carina.
    • The bronchi enter the lungs at the hilum, along with pulmonary arteries and veins.
    • The primary bronchi further branch into lobar bronchi (secondary bronchi), then into segmental bronchi (tertiary bronchi).
    • Bronchioles connect to the alveolar sacs through alveolar ducts.
    • Alveolar sacs contain alveoli, the site of gas exchange.

    Lung Lobes

    • The right lung has three lobes: upper, middle, and lower.
    • The left lung has two lobes: upper and lower.

    Lung Layers

    • The lungs have two layers: the visceral layer and the parietal layer.
    • Serous fluid between the layers allows the lungs to glide smoothly during breathing.

    Inhalation and Exhalation

    • The diaphragm contracts during inhalation, creating negative pressure in the chest cavity and drawing air into the lungs.
    • The diaphragm relaxes during exhalation, creating positive pressure in the lungs and forcing air out.
    • Gas exchange occurs within the alveoli, where oxygen enters the bloodstream and carbon dioxide leaves.

    Microscopic Gas Exchange

    • Capillaries surrounding the alveoli receive unoxygenated blood from the pulmonary artery.
    • Carbon dioxide diffuses from the blood into the alveoli to be exhaled.
    • Oxygen diffuses from the alveoli into the blood, attaching to red blood cells.
    • Oxygenated blood is returned to the heart through the pulmonary vein.

    Lung Anatomy

    • Lungs are responsible for removing carbon dioxide (CO2) and replenishing oxygen (O2) in the body through breathing.
    • The upper respiratory system includes the nasal cavities, pharynx, and larynx.
    • The lower respiratory system consists of the trachea, bronchi (primary, secondary, tertiary, bronchioles), alveolar ducts, alveoli, and alveolar sacs.
    • The primary bronchi, pulmonary arteries, and veins enter the lungs at the hilum.
    • The right lung has three lobes: upper, middle, and lower.
    • The left lung has two lobes: upper and lower.
    • The lungs have two layers: the visceral layer (surrounding the lungs) and the parietal layer (surrounding the thoracic cavity).
    • Serous fluid between the visceral and parietal layers prevents friction during breathing.

    Gas Exchange

    • During inhalation, the diaphragm contracts, creating negative pressure in the chest cavity, causing air to be drawn into the lungs.
    • Oxygen (O2) diffuses from the alveoli into the capillaries, where it binds to red blood cells.
    • Carbon dioxide (CO2) diffuses from the capillaries into the alveoli, where it is exhaled.
    • Pulmonary arteries carry deoxygenated blood from the heart to the lungs for oxygenation.
    • Pulmonary veins carry oxygenated blood back to the heart.
    • Gas exchange within the alveoli occurs through a thin capillary wall.

    Lung Function

    • Lungs are responsible for gas exchange, removing carbon dioxide and replenishing oxygen.
    • Carbon dioxide is a waste product of metabolism.
    • Oxygen is essential for cellular function.
    • Heart and lungs work together to circulate oxygenated blood throughout the body.

    Lung Anatomy

    • Air travels through the upper respiratory system, including the nose, mouth, pharynx, and larynx.
    • It then travels through the lower respiratory system, including the trachea, bronchi, bronchioles, and alveoli.
    • The trachea branches into two bronchi, one for each lung, at the carina.
    • Bronchi enter the lungs at the hilum, along with blood vessels.
    • Bronchi branch further into bronchioles, which lead to alveoli.
    • Alveoli are tiny air sacs where gas exchange occurs.
    • Alveolar sacs are clusters of alveoli.

    Lung Structure

    • The right lung has three lobes, while the left lung has two.
    • Each lung is surrounded by two layers of pleura: visceral pleura (attached to lung) and parietal pleura (lines the thoracic cavity).
    • Serous fluid between the pleura allows for smooth gliding during breathing.

    Mechanism of Breathing

    • Inhalation is an active process where the diaphragm contracts, flattens, and creates negative pressure, drawing air into the lungs.
    • Exhalation is a passive process where the diaphragm relaxes, creating positive pressure, forcing air out of the lungs.

    Gas Exchange at Alveoli

    • Oxygen in inhaled air diffuses across the thin alveolar wall into capillaries and attaches to red blood cells.
    • Carbon dioxide from red blood cells diffuses across the alveolar wall into the air to be exhaled.
    • This constant exchange occurs between the alveoli and capillaries to maintain oxygen levels and remove carbon dioxide.

    Pulmonary Disease

    • Increased resistance to airflow requires more force to breathe and increased energy demand for ventilation
    • Chronic Obstructive Pulmonary Disease (COPD) is a progressive disorder that restricts airflow and reduces alveolar ventilation
      • Asthma (asthmatic bronchitis) is acute and intermittent, characterized by conducting passageways sensitive to irritation, causing smooth muscle constriction, edema/swelling of mucosa, and increased mucus, leading to difficult breathing and increased resistance. Triggers include allergies, toxins, and exercise.
      • Chronic bronchitis is long-term inflammation and swelling of the bronchial lining, leading to overproduction of mucus, frequent coughing, and sputum clogging airways, increasing resistance and reducing efficiency. Cigarette smoking is the most common cause but other environmental irritants also play a role. Chronic bacterial infections can damage lungs, contributing to cyanosis known as "blue bloaters."
      • Emphysema is a chronic, progressive condition where alveoli gradually expand/merge, resulting in loss of elastic tissues and increased lung compliance. This loss of respiratory surface area restricts oxygen absorption, causing shortness of breath and intolerance of physical exertion. Heavy breathing with pink coloration is known as "pink puffers."

    Respiratory Muscles and Pulmonary Function

    • Accessory Expiratory Muscles include internal intercostals, transversus thoracis, external oblique, internal oblique, and rectus abdominis.
      • Internal intercostals and transversus thoracis depress ribs.
      • Abdominal muscles push the diaphragm upward.
      • These muscles decrease thoracic cavity volume quickly, allowing greater pressure change and faster airflow out of the lungs.

    Pulmonary Function Tests

    • Pulmonary function tests measure rates and volumes of air movement to monitor respiratory function.
      • Respiratory Volumes:
        • Tidal Volume (VT): Amount of air moved in or out during a single respiratory cycle at rest, averaging 500 mL.
        • Inspiratory Reserve Volume (IRV): Additional air inhaled beyond tidal volume.
        • Expiratory Reserve Volume (ERV): Air exhaled beyond tidal volume after normal exhalation.
        • Residual Volume: Air left after maximal exhalation.
        • Minimal Volume: Air remaining in the lungs if they were allowed to collapse, included in residual volume, and cannot be measured in healthy individuals.

    Respiratory Control Mechanisms

    • Respiratory control involves multiple levels of regulation.
      • Respiratory rate and rhythm are controlled by a network of respiratory centers in the brainstem, primarily outside conscious control.
      • Level 1: Respiratory Rhythmicity Centers represent the most basic level of control.
        • Pacemaker cells in the medulla oblongata generate cycles of contractions in the diaphragm.
        • Paired respiratory rhythmicity centers establish the pace of respiration by adjusting pacemaker cells and coordinating other respiratory muscles.
        • Each center is subdivided into two groups:
          • Dorsal Respiratory Group (DRG): Primarily concerned with inspiration and controls lower motor neurons to primary inspiratory muscles (external intercostals, diaphragm). Receives input from chemoreceptors, detecting O2, CO2, and pH levels in blood/CSF, and baroreceptors (stretch receptors) monitoring the stretch of the lung wall.
          • Ventral Respiratory Group (VRG): Mainly associated with expiration, functioning only when breathing demands increase and accessory respiratory muscles are involved.
        • Pre-Bötzinger complex in the medulla is essential for all forms of breathing but remains poorly understood.

    Carbon Dioxide Transport

    • Respiratory gas equilibrium is maintained within the alveoli and tissues.
      • Equilibrium disruptions occur when tissue oxygen demand increases.
        • Respiratory rate and tidal volume must increase to maintain equilibrium.
        • Without an increase, alveolar PO2 levels decrease, and alveolar, blood, and tissue PCO2 levels increase, leading to hypoxia and a dangerous drop in pH.

    Pulmonary Disease Impact on Lung Elasticity & Airflow

    • Lung Compliance:
      • Indicates how easily the lungs expand.
      • Influenced by internal lung structures (elasticity and resilience) and flexibility of the chest wall.
      • Determined by monitoring intrapulmonary pressure at different lung volumes.
    • Lung Resistance:
      • Indicates the force required to inflate/deflate lungs.
      • Muscular activity of pulmonary ventilation accounts for 3-5% of resting energy demand.

    Gas Volume and Pressure

    • Boyle's Law: Pressure is inversely proportional to volume (P = 1/V).
      • Increased volume causes decreased pressure - and vice versa.
    • Changing the volume of the thoracic cavity affects lung volume and pressure.
      • Movements of the diaphragm and rib cage change thoracic cavity volume, which expands or compresses the lungs.
      • Changes in volume lead to corresponding changes in pressure.

    Pulmonary Ventilation & Pressure Changes

    • Start of a Breath:
      • Pressures inside and outside the thorax are identical, with no air movement.
      • Expanding the thoracic cavity expands the lungs, as parietal pleura is attached to the thoracic wall and visceral pleura to the lungs, with pleural fluid forming a bond between the layers.
        • Injury allowing air into the pleural cavity breaks this bond and causes lung collapse (atelectasis).
    • Air Flow:
      • Air flows from higher to lower pressure.
      • During inhalation, the thoracic cavity expands and decreases pressure within, causing air to flow from the outside higher pressure area to the inside lower pressure area.

    The Respiratory Defense System

    • Respiratory mucosa lines the nasal cavity through large bronchioles.
    • Pseudostratified ciliated columnar epithelium with mucous cells lines the respiratory mucosa.
    • Lamina propria is the underlying areolar tissue that supports the respiratory epithelium.
    • The respiratory tract contains mucous glands in the trachea and bronchi.
    • The mucociliary escalator is a flow of mucus and trapped debris.
    • The mucociliary escalator transports debris toward the pharynx where it is swallowed or coughed out.
    • Epithelial stem cells replace damaged or old cells.

    Epithelia of the Respiratory Tract

    • Specific types of epithelial tissue vary along the respiratory tract.
    • Respiratory mucosa lines the nasal cavity and superior pharynx as well as the superior portion of the lower respiratory tract.
    • Stratified squamous epithelium lines the inferior portions of the pharynx
    • Simple squamous epithelium forms gas exchange surfaces where the distance between air and the blood in capillaries is less than 1µm.

    Pulmonary Ventilation: Boyle's Law

    • During exhalation, the thoracic cavity decreases in volume causing an increase in pressure.
    • This increase in pressure forces air out of the lungs from an area of high pressure to low pressure.
    • The direction of airflow is determined by the difference between atmospheric pressure and intrapulmonary pressure.
    • Intrapulmonary pressure is the pressure inside the respiratory tract and is usually measured at the alveoli.

    Tidal Volume

    • Tidal volume is the volume of air moved into and out of the lungs during a normal breath.
    • During inhalation, intrapulmonary pressure is less than atmospheric pressure, causing negative intrapulmonary pressure.
    • Negative intrapulmonary pressure pulls air into the lungs.
    • During exhalation, intrapulmonary pressure is greater than atmospheric pressure, causing positive intrapulmonary pressure.
    • Positive intrapulmonary pressure pushes air out of the lungs.

    Carbon Dioxide Transport

    • Respiratory gas equilibrium refers to the stabilization of PO2 and PCO2 in the alveoli and tissues.
    • If tissue oxygen demand increases, respiratory rate and tidal volume must also increase.
    • When respiratory rate and tidal volume do not increase with increased oxygen demand, alveolar PO2 levels decrease, and alveolar, blood, and tissue PCO2 levels increase.
    • This can lead to hypoxia and dangerous drops in pH.

    Compliance and Resistance of the Lungs

    • The compliance of the lungs refers to how easily they can expand.
    • The compliance of the lungs is influenced by both internal lung structures (elasticity and resilience) and the flexibility of the chest wall.
    • The resistance of the lungs indicates the force required to inflate/deflate the lungs.
    • Pulmonary ventilation requires 3-5 percent of resting energy demand.

    Chronic Obstructive Pulmonary Diseases

    • There are three chronic obstructive pulmonary diseases (COPDs).

    Respiratory Control Mechanisms

    • Respiration is regulated by a network of respiratory centers in the brainstem.
    • Most regulation occurs out of conscious control.

    Respiratory Rhythmicity Centers

    • The respiratory rhythmicity centers in the medulla oblongata generate cycles of contractions in the diaphragm, establishing the pace of respiration.
    • The respiratory rhythmicity centers are subdivided into the dorsal respiratory group (DRG) and the ventral respiratory group (VRG).
    • The DRG primarily controls inspiration and is concerned with lower motor neurons to primary inspiratory muscles (external intercostals, diaphragm).
    • The VRG is mainly associated with expiration, and functions only when breathing demands increase and accessory respiratory muscles are involved.
    • The pre-Bӧtzinger complex is located in the medulla, and is essential to all forms of breathing but the exact role is not well understood.

    Apneustic and Pneumotaxic Centers

    • Apneustic and pneumotaxic centers are located in the pons and adjust the output of the respiratory rhythmicity centers.
    • Apneustic centers promote inhalation by stimulating the DRG, the degree of stimulation is adjusted based on sensory information from the vagus nerve about lung inflation.
    • Pneumotaxic centers inhibit apneustic centers and promote passive or active exhalation.
    • Increased pneumotaxic output shortens inhalation duration, leading to a faster respiratory rate.
    • Decreased output slows the pace and increases the depth of respiration.

    Higher Centers

    • Higher centers are located in the hypothalamus, limbic system, and the cerebral cortex
    • Higher centers can alter the activity of pneumotaxic centers.
    • Normal breathing can occur without higher center input.

    Upper Respiratory System Structures

    • The upper respiratory system includes the paranasal sinuses, nasal septum, nasal cavity, pharynx, and trachea.
    • The four paranasal sinuses: frontal, ethmoidal, maxillary, and sphenoidal, secrete mucus to moisten and clean the nasal cavity surfaces.
    • The nasal septum is made up of the vomer and perpendicular plate of the ethmoid bone.
    • The lamina propria of the nasal cavity contains an extensive network of veins which release heat to warm inhaled air and evaporate water from mucus to humidify inhaled air
    • The pharynx is shared by the respiratory and digestive systems and consists of the nasopharynx, oropharynx, and laryngopharynx.
    • The nasopharynx is the superior part of the pharynx and lies above the soft palate.
    • The oropharynx is located between the soft palate and the base of the tongue.
    • The laryngopharynx is found between the hyoid bone and the larynx.
    • The trachea is a cartilaginous tube that conducts air to the lungs.
    • The nasal vestibule is the space at the front of the nasal cavity, where coarse hairs trap large airborne particles.
    • The nasal cavity opens into the nasopharynx through the choanae.
    • The bony hard palate forms the floor of the nasal cavity, separating the nasal and oral cavities.
    • The soft palate is the fleshy part posterior to the hard palate.
    • The glottis is the opening into the larynx.
    • The larynx is mostly cartilage and surrounds and protects the glottis.
    • The trachea conducts air towards the lungs.

    Pulmonary Ventilation

    • Pulmonary ventilation, or breathing, is driven by pressure changes within the pleural cavities.
    • Gas molecules bounce around independently and collide with the walls of their container, creating pressure.
    • Pressure is inversely related to volume (P = 1/V), which is Boyle's Law.
    • Expanding the thoracic cavity expands the lungs, changing lung volume and pressure, which causes air movement.
    • During inhalation, the thoracic cavity enlarges, increasing volume and decreasing pressure, resulting in air flowing from the outside, where pressure is higher, to the inside, where pressure is lower.
    • During exhalation, the thoracic cavity decreases in volume and increases pressure, causing air to be expelled from the lungs.

    Gas Diffusion and Transport

    • The partial pressures of gases vary by location in the respiratory tract, depending on the composition of the air mixture.
    • Henry's law states that the amount of a particular gas dissolved in a solution is directly proportional to the partial pressure of that gas.
    • External respiration involves the diffusion of gases between the alveoli and pulmonary capillaries, increasing blood PO2 and decreasing PCO2, as oxygen enters the blood and carbon dioxide leaves.
    • Internal respiration is the diffusion of gases between the blood and interstitial fluid, delivering oxygen to tissues and removing carbon dioxide.
    • Carbon dioxide is transported in the blood in three ways: dissolved in plasma, bound to hemoglobin, and converted to bicarbonate ion.
    • Approximately 70% of carbon dioxide entering the blood is converted to bicarbonate ion, a reversible reaction catalyzed by carbonic anhydrase.
    • The conversion of carbon dioxide to carbonic acid and subsequent dissociation into bicarbonate and hydrogen ions results in the formation of carbaminohemoglobin, a compound bound to hemoglobin.
    • Bicarbonate ions are exchanged for chloride ions in a process known as the 'chloride shift'.

    Respiratory Reflexes

    • Inflation and deflation reflexes are activated by stretch receptors in the lungs during forced breathing.
    • These reflexes prevent overexpansion or deflation of the lungs.
    • Protective reflexes, such as sneezing and coughing, are triggered by irritants and involve apnea followed by forceful expulsion of air.

    Respiratory Function and Aging

    • Respiratory function, including vital capacity, decreases with age due to deterioration of elastic tissue and stiffening of rib joints.
    • Smoking contributes to the decline of respiratory function and increases the severity of emphysema in individuals over 50 years of age.

    Respiratory Defense System

    • Lines the nasal cavity through large bronchioles
    • Mucociliary escalator moves mucus and debris
    • Mucus traps debris particles
    • Cilia beat to move the mucus toward the pharynx
    • Epithelial stem cells replace damaged or old cells

    Respiratory Epithelium

    • Structure changes along the respiratory tract
    • Respiratory mucosa lines the nasal cavity and superior portion of the lower respiratory tract
    • Stratified squamous epithelium lines the pharynx
    • Simple squamous epithelium forms gas exchange surfaces

    Upper Respiratory System

    • Consists of the nasal cavity, sinuses, pharynx, and larynx
    • Nasal Cavity:
      • Has a nasal vestibule with coarse hairs
      • Open into the nasopharynx through the choanae
      • Separated from the oral cavity by the hard and soft palates
    • Paranasal Sinuses:
      • Frontal, ethmoidal, maxillary, and sphenoidal sinuses
      • Secrete mucus to moisten and clean nasal cavity surfaces
    • Pharynx:
      • Shared by respiratory and digestive systems
      • Divided into nasopharynx, oropharynx, and laryngopharynx
    • Larynx (Voice Box):
      • Contains the epiglottis and vocal cords
    • Trachea (Windpipe):
      • Conducts air to the lungs

    Vascularization of Nasal Cavity

    • Extensive network of veins in the lamina propria
    • Releases heat to warm inhaled air
    • Evaporates water to humidify inhaled air
    • Mouth breathing eliminates these benefits

    Pulmonary Ventilation

    • Driven by pressure changes within the pleural cavities
    • Boyle's Law: pressure is inversely proportional to volume
    • Volume changes in the thoracic cavity cause pressure changes in the lungs

    Inhalation

    • The thoracic cavity expands, causing a decrease in pressure within the lungs
    • Air flows from an area of higher pressure (outside) to lower pressure (inside)
    • The diaphragm contracts and flattens, increasing the volume of the thoracic cavity

    Exhalation

    • The thoracic cavity contracts, causing an increase in pressure within the lungs
    • Air flows from an area of higher pressure (inside) to lower pressure (outside)
    • The diaphragm relaxes and moves upward, decreasing the volume of the thoracic cavity

    Oxygen-Hemoglobin Saturation Curve

    • Hemoglobin in blood entering the systemic circuit is 97% saturated
    • Hemoglobin in blood leaving body tissues is 75% saturated
    • Hemoglobin in blood in active muscle is only 20% saturated

    Factors Affecting Hemoglobin Saturation

    • Bohr effect:
      • Blood pH directly affects hemoglobin saturation
      • Lower pH shifts the curve to the right
      • Higher pH shifts the curve to the left
    • Temperature:
      • Higher temperature leads Hb to release oxygen more readily
    • BPG (2,3-bisphosphoglycerate):
      • Higher BPG levels leads to more oxygen release by Hb molecules
      • BPG production declines as RBCs age

    Respiratory Control Mechanisms

    • Respiratory rhythmicity centers: located in the medulla oblongata
    • Apneustic centers: promote inhalation
    • Pneumotaxic centers: promote exhalation
    • Higher centers: located in the hypothalamus, limbic system, and cerebral cortex
    • Chemical factors in blood or cerebrospinal fluid stimulate respiratory centers:
      • Increased carbon dioxide levels
      • Decreased oxygen levels
      • Increased hydrogen ion concentrations
    • Neural control of respiration is regulated by chemoreceptors and mechanoreceptors

    Quiet Breathing

    • Diaphragm contracts and flattens during inhalation, chest wall expands
    • Diaphragm relaxes and dome shape is restored during exhalation, chest wall recoils

    Forced Breathing

    • Inhalation requires both diaphragm contraction and accessory muscle contraction
    • Exhalation requires contraction of abdominal muscles, internal intercostals, and other accessory muscles, increasing pressure in the thoracic cavity.

    Cystic Fibrosis

    • Most common lethal inherited disease in individuals of Northern European descent
    • Mucosa produces thick mucus that cannot be transported
    • Mucociliary escalator stops clearing debris/pathogens; causes frequent infections (for example, Pseudomonas aeruginosa)
    • Average lifespan for people with CF who live to adulthood is 37
    • Death generally from heart failure and chronic bacterial lung infection

    Respiratory Defense System

    • The conducting portion of the respiratory tract is lined by a mucous membrane
    • Cystic fibrosis can become lethal because it impairs the mucociliary escalator, which normally clears debris and pathogens from the respiratory tract, making individuals more susceptible to infections.

    Upper Respiratory System

    • The upper respiratory system includes the nose, nasal cavity, paranasal sinuses, and pharynx
    • The nose is the primary route for air entering the respiratory system
    • The dorsum of the nose (bridge) is formed by two nasal bones supported by hyaline cartilage
    • Nasal cartilages - small, elastic cartilages extending laterally from the bridge, helping keep nostrils open
    • Nostrils (external nares) are paired openings into the nasal cavity

    Nasal Cavity Structures

    • Superior, middle, and inferior nasal conchae
    • Superior, middle, and inferior nasal meatuses
      • Passages between nasal conchae
      • Swirl incoming air to trap small particles
      • Moves chemicals to olfactory receptors
      • Warms and humidifies air

    Gas Laws

    • Gas mixture inside respiratory tract varies by location
      • Inhaled air gets moistened and warmed.
      • In alveoli, it mixes with air remaining from the previous breath
      • Exhaled air mixes with air in anatomical dead space
    • As gas mixture varies, so do the partial pressures of its component gases

    Henry's Law

    • At a given temperature, the amount of a particular gas in solution is directly proportional to the partial pressure of that gas

    External Respiration

    • Blood arriving in pulmonary arteries has lower PO2 and higher PCO2 than in alveolar air
    • Diffusion between alveolar mixture and pulmonary capillaries:
      • Increases blood PO2 (oxygen enters blood)
      • Decreases PCO2 (carbon dioxide leaves blood)

    Internal Respiration

    • PO2 of blood leaving the lungs in pulmonary veins drops slightly when it mixes with blood from capillaries around conducting passageways, but is still higher than PO2 of interstitial fluid
    • Oxygen diffuses to interstitial fluid
    • PCO2 higher in tissues/interstitial fluid than in blood
    • Carbon dioxide diffuses from tissues into blood

    Oxygen-Hemoglobin Saturation Curve

    • Hemoglobin in blood entering the systemic circuit is ~97 percent saturated (PO2 is 95 mm Hg)
    • Hemoglobin in blood leaving body tissues is ~75 percent saturated (PO2 is 40 mm Hg)
      • Substantial oxygen reserves are present even in venous blood
    • Hemoglobin in deoxygenated blood in active muscle is only ~20 percent saturated. (PO2 is only ~15–20 mm Hg)

    Blood PH and Hemoglobin Saturation

    • Decreases in blood pH shift the saturation curve to the right
    • Increases in blood pH shift the saturation curve to the left

    Temperature and Hemoglobin Saturation

    • Higher temperatures lead to Hb releasing oxygen more readily
    • This is especially important in active tissues as they generate heat

    2,3-Bisphosphoglycerate (BPG)

    • RBCs lack mitochondria – make ATP only through glycolysis.
    • The same metabolic pathways produce 2,3-bisphosphoglycerate (BPG)
      • The higher the BPG; the more oxygen will be released by Hb molecules.
      • BPG production declines as RBCs age.

    Chronic Obstructive Pulmonary Disease (COPD)

    • General term for a progressive disorder of the airways that restricts airflow and reduces alveolar ventilation
    • Three examples of COPD:
      • Asthma (asthmatic bronchitis)
      • Chronic bronchitis
      • Emphysema

    Asthma (asthmatic bronchitis)

    • Used when obstructive symptoms are acute and intermittent.
    • Characterized by conducting passageways that are extremely sensitive to irritation
    • Airways respond by constricting smooth muscles along the bronchial tree, edema/swelling of mucosa, increased mucus
    • Breathing is difficult, resistance markedly increased
    • Triggers include allergies, toxins, exercise

    Chronic Bronchitis

    • Long-term inflammation and swelling of bronchial lining; leads to overproduction of mucus
    • Frequent cough, lots of sputum can clog airways, increasing resistance, reduced efficiency
    • Cigarette smoking is the most common cause
      • Other environmental irritants are possible causes.
    • Chronic bacterial infections can damage lungs
    • "Blue bloaters" - a term for people with cyanosis, due to this disorder

    Emphysema

    • Chronic, progressive condition
    • Alveoli gradually expand/merge with adjacent alveoli.
    • Loss of elastic tissues increases compliance
    • Loss of respiratory surface area restricts oxygen absorption (shortness of breath, intolerance of physical exertion)
    • "Pink puffers" - a term for people with emphysema; heavy breathing with pink coloration

    Compliance and Resistance

    • Compliance is a measure of how easily the lungs expand and contract
    • Resistance is a measure of how difficult it is for air to flow through the airways

    Respiratory Control Mechanisms: Apneustic and Pneumotaxic Centers

    • Paired nuclei in the pons adjust the output of the respiratory rhythmicity centers
    • Apneustic centers promote inhalation by stimulating the dorsal respiratory group (DRG)
      • Degree of stimulation adjusted based on sensory information from the vagus nerve about lung inflation
    • Pneumotaxic centers inhibit apneustic centers
      • Promote passive or active exhalation
      • Increased pneumotaxic output shortens inhalation duration (= faster respiratory rate)
      • Decreased output slows pace and increases depth of respiration

    Respiratory Control Mechanisms: Higher Centers

    • Located in the hypothalamus, limbic system, and cerebral cortex
    • Can alter activity of pneumotaxic centers.
      • Normal breathing can occur without higher input

    Respiratory Control Mechanisms: Chemical Factors

    • Increased carbon dioxide levels in the blood
    • Decreased oxygen levels in the blood
    • Increased hydrogen ion concentration (acidity) in the blood (all will stimulate the respiratory centers)

    Brainstem Centers

    • Dorsal respiratory group (DRG) and ventral respiratory group (VRG) - generate the respiratory pace
    • The DRG contains neurons that control inspiration
    • The VRG contains, inspiratory neurons, expiratory neurons, and neurons that control the diaphragm

    Upper respiratory system

    • Paranasal sinuses
      • Frontal sinus, ethmoidal air cells, maxillary sinus, sphenoidal sinus
      • Mucus secreted by sinuses moistens and cleans nasal cavity surfaces and drains with tears through the nasolacrimal duct
    • Nasal septal formation
      • Formed by vomer and perpendicular plate of the ethmoid bone
    • Lamina propria of the nasal cavity
      • Has extensive network of veins
      • Releases heat to warm inhaled air
      • Water evaporates from mucus to humidify inhaled air
      • Air moving from nasal cavity to lungs is heated to nearly body temperature and saturated with water vapor
      • During exhalation, mucosa reabsorbs heat and water to reduce heat and water loss to the environment
      • Mouth breathing eliminates this benefit
    • Pharynx
      • Shared by the respiratory and digestive systems
      • Nasopharynx: Superior part extending to the soft palate
        • Contains pharyngeal opening of the auditory tube
      • Oropharynx: Soft palate to the base of the tongue
        • Stratified squamous epithelium
      • Laryngopharynx: Hyoid bone to the larynx
    • Trachea
      • Conducting passageway from the larynx to the bronchi
    • Other key parts of the upper respiratory tract
      • Nasal vestibule: Space at the front of the nasal cavity
        • Coarse hairs trap large airborne particles
      • Nasal cavity: Opens into the nasopharynx through the choanae
      • Hard palate: Bony floor of the nasal cavity
        • Separates nasal/oral cavities
      • Soft palate: Fleshy part posterior to the hard palate
      • Glottis: Opening into the larynx
      • Larynx: Mostly cartilage; surrounds and protects the glottis
      • Trachea conducts air toward the lungs

    Lower respiratory system

    • Trachea (windpipe)
      • Ends of each C-shaped tracheal cartilage connected by an elastic ligament and trachealis (muscle)
        • Contraction of trachealis narrows the trachea and restricts airflow
        • Diameter changes often, mostly controlled by sympathetic stimulation (increases airflow)
        • Cartilages are incomplete posteriorly, allowing expansion during swallowing
    • Bronchioles
      • No cartilage; thick smooth muscle
      • Sympathetic nervous system: Causes bronchodilation (increases airflow)
      • Parasympathetic nervous system: Causes bronchoconstriction (decreases airflow)
      • Extreme bronchoconstriction can occur during allergic reactions like asthma
    • Bronchial tree
      • Terminal bronchioles: Lead to pulmonary lobules (gas exchange)
      • Respiratory bronchioles: Last division
      • Trachea: Larynx to main bronchi in mediastinum
      • Main bronchi: One to each lung; cartilage rings are complete
      • Lobar bronchi: Three in the right lung, two in the left; one per lobe
      • Segmental bronchii: Branch to give rise to bronchioles
      • Bronchi branch into smaller and smaller tubes, diameter decreases with each new branch

    Respiratory physiology

    • Respiration
      • Two integrated processes: External respiration & Internal respiration
      • External respiration: Exchange of gases between the blood, lungs, and external environment
        • Gas diffusion occurs across the blood-air barrier between alveolar air and alveolar capillaries
        • Pulmonary ventilation: Air movement in/out of the lungs
        • Alveolar ventilation: Air movement in/out of alveoli
      • Internal respiration: Occurs between blood and tissues
        • Absorption: Oxygen from blood
        • Release: Carbon dioxide by tissue cells
    • Abnormalities affecting external respiration
      • Hypoxia: Low tissue oxygen levels, severely limits metabolic activities
      • Anoxia: No oxygen supply, much of damage caused by heart attacks and strokes is the result of localized anoxia
    • Pulmonary ventilation
      • During exhalation: Thoracic cavity decreases in volume, increased pressure, air is forced out from high to low pressure
      • Direction of airflow determined by the difference between:
        • Atmospheric pressure: Pressure of the air around us
        • Intrapulmonary pressure: Pressure inside the respiratory tract (usually measured at the alveoli)
      • Tidal volume: Volume of air moved in and out of lungs in normal breath
        • Inhalation: Intrapulmonary pressure < atmospheric pressure, negative intrapulmonary pressure pulls air into lungs
        • Exhalation: Intrapulmonary pressure > atmospheric pressure, positive intrapulmonary pressure pushes air out of the lungs

    Pulmonary disease

    • Compliance: How easily lungs expand
      • Increased compliance: Lungs expand easily
      • Decreased compliance: Lungs expand with difficulty
    • Resistance: Difficultly of airflow within the respiratory passageways
      • Increased resistance: Increased effort/force needed for breathing, increased energy demand for ventilation
      • Chronic obstructive pulmonary disease (COPD): Progressive disorder of the airways that restricts airflow and reduces alveolar ventilation:
        • Examples of COPD:
          • Asthma (asthmatic bronchitis): Acute, intermittent symptoms, conducting passageways extremely sensitive to irritation, airways constrict smooth muscles, edema/swelling of mucosa, increased mucus, breathing difficulty, resistance markedly increased, triggers include allergies, toxins, exercise
          • Chronic bronchitis: Long-term inflammation and swelling of the bronchial lining; leads to overproduction of mucus, frequent cough, lots of sputum can clog airways, increased resistance, reduced efficiency, cigarette smoking most common cause, also other environmental irritants, chronic bacterial infections can damage lungs, "blue bloaters"--term for people with cyanosis due to this disorder
          • Emphysema: Chronic, progressive condition, alveoli gradually expand and merge with adjacent alveoli, loss of elastic tissues increases compliance, loss of respiratory surface area restricts oxygen absorption (shortness of breath, intolerance of physical exertion), "pink puffers"--term for people with emphysema--heavy breathing with pink coloration

    Pulmonary Lobules: Structure and Gas Exchange

    • Pulmonary lobules are the functional units of the lungs, containing alveoli where gas exchange occurs.
    • A segmental bronchus supplies a bronchopulmonary segment, which is further divided into terminal bronchioles.
    • Each terminal bronchiole supplies a single pulmonary lobule.
    • Terminal bronchioles branch into respiratory bronchioles, leading to alveolar ducts and then alveolar sacs.

    Alveoli: Sites of Gas Exchange

    • There are approximately 150 million alveoli per lung, giving the lungs a spongy appearance.
    • Alveoli are surrounded by an extensive capillary network, facilitating gas exchange.
    • Elastic fibers surrounding alveoli aid in expansion and recoil, assisting air movement.

    Pleurae: Serous Membranes Surrounding the Lungs

    • Visceral pleura covers the outer surface of the lungs.
    • Parietal pleura lines the inner surface of the thoracic wall, extending over the diaphragm and mediastinum.
    • The pleural cavity, a potential space between the visceral and parietal pleura, contains pleural fluid to reduce friction during breathing.

    Alveolar Epithelium: Cell Types and Functions

    • Alveolar epithelium consists of three major cell types:
      • Pneumocytes type I: Thin and delicate cells responsible for gas diffusion.
      • Pneumocytes type II: Produce surfactant, an oily secretion that reduces surface tension of water in alveoli, preventing collapse.

    Cystic Fibrosis: A Lethal Inherited Disease

    • Cystic fibrosis (CF) is the most common lethal inherited disease in individuals of Northern European descent.
    • CF causes the production of thick mucus that cannot be transported effectively by the mucociliary escalator.
    • This leads to frequent infections, particularly by bacteria like Pseudomonas aeruginosa.
    • Reduced lung function and chronic infections contribute to a shortened lifespan, with an average of 37 years for those who live to adulthood.

    Respiratory Defense System: Protecting the Delicate Respiratory Surfaces

    • The respiratory defense system protects the respiratory system from pathogens, debris, and other hazards.
    • The conducting portion of the respiratory tract is lined by a mucous membrane that traps foreign particles.
    • The mucociliary escalator, a mechanism involving cilia and mucus, transports trapped substances upwards, allowing them to be expelled.
    • Cystic fibrosis disrupts the mucociliary escalator, leading to increased susceptibility to infections.

    Upper Respiratory System: Anatomy and Functions

    • The upper respiratory system includes the nose, nasal cavity, paranasal sinuses, and pharynx.
    • The nose is the primary route for air entering the respiratory system.
    • Nasal conchae, bony structures within the nasal cavity, create turbulence in incoming air, trapping small particles, warming/humidifying air, and directing chemicals to the olfactory receptors.

    Pulmonary Ventilation: Air Movement into and out of the Lungs

    • During inhalation, the thoracic cavity expands, decreasing intrapulmonary pressure below atmospheric pressure, which pulls air into the lungs.
    • During exhalation, the thoracic cavity contracts, increasing intrapulmonary pressure above atmospheric pressure, forcing air out of the lungs.
    • Tidal volume refers to the volume of air moved into and out of the lungs during normal breathing.

    Effects of Aging and Smoking on the Respiratory System

    • Lung cancer is an aggressive malignancy affecting epithelial cells in the respiratory system.
    • Cigarette smoke contains carcinogens that damage respiratory epithelium, leading to progressive changes:
      • Dysplasia: Reversible damage, involving cell changes and impaired ciliary function.
      • Metaplasia: Reversible structural tissue changes, where stressed epithelium converts to a more protective stratified epithelium.
    • Both dysplasia and metaplasia can increase the risk of lung cancer.

    Pulmonary Lobules and Alveoli

    • Pulmonary lobules are the smallest functional units of the lung.
    • Each lobule is supplied by a terminal bronchiole.
    • Terminal bronchioles branch into respiratory bronchioles.
    • Respiratory bronchioles lead to alveolar ducts and alveolar sacs.
    • Alveoli:
      • Around 150 million alveoli per lung.
      • Responsible for gas exchange.
      • Surrounded by an extensive capillary network.
      • Composed of thin-walled sacs for efficient diffusion.
      • Surrounded by elastic fibers, which help with expansion and recoil during breathing.

    Pleurae

    • Pleurae are serous membranes surrounding the lungs.
    • Visceral pleura covers the outer surface of the lungs.
    • Parietal pleura covers the inner surface of the thoracic wall, diaphragm, and mediastinum.
    • Pleural cavity is the potential space between the visceral and parietal pleura.
    • It contains pleural fluid, which reduces friction during breathing.

    Alveolar Epithelium

    • Composed of three types of cells:
      • Type I pneumocytes: thin and delicate cells responsible for gas diffusion.
      • Type II pneumocytes: produce surfactant, an oily secretion that reduces surface tension in alveoli and prevents collapse.
      • Other cells: macrophages, which engulf debris and pathogens.

    Larynx

    • Cartilaginous tube that surrounds and protects the glottis.
    • Contains three large cartilages:
      • Epiglottis: prevents food from entering the respiratory tract during swallowing.
      • Thyroid cartilage: forms the Adam's apple.
      • Cricoid cartilage: provides a complete ring around the larynx for protection.
    • Also contains small paired cartilages:
      • Cuneiform cartilages: located within folds of tissue between arytenoid cartilages and the epiglottis.
      • Corniculate cartilages: articulate with the arytenoid cartilages.
      • Arytenoid cartilages: articulate with the superior surface of the cricoid cartilage.

    Trachea

    • Cartilaginous tube connecting the larynx to the main bronchi.
    • Composed of C-shaped cartilages that allow expansion during swallowing.
    • Contraction of the trachealis muscle can narrow the trachea and restrict airflow.

    Bronchi

    • Main bronchi: one to each lung; cartilage rings are complete.
    • Lobar bronchi: three in the right lung, two in the left; one per lobe.
    • Segmental bronchi: branch to give rise to bronchioles.
    • Bronchioles: smaller, branching tubes with no cartilage but thick smooth muscle.
      • Sympathetic stimulation causes bronchodilation (increased airflow).
      • Parasympathetic stimulation causes bronchoconstriction (decreased airflow).

    Respiratory Control Mechanisms

    • Level 1: Respiratory rhythmicity centers: located in the medulla oblongata; generate the basic respiratory pace by alternating between inspiratory and expiratory phases.
    • Level 2: Apneustic and pneumotaxic centers: located in the pons; adjust the output of the respiratory rhythmicity centers.
      • Apneustic centers: promote inhalation by stimulating the dorsal respiratory group (DRG).
      • Pneumotaxic centers: inhibit apneustic centers and promote exhalation; help regulate the duration and depth of inspiration.
    • Level 3: Higher centers: located in the hypothalamus, limbic system, and cerebral cortex; can alter the activity of the pneumotaxic centers, but normal breathing can occur without higher input.

    Respiratory Reflexes

    • Chemoreceptor reflexes: monitor blood and cerebrospinal fluid for changes in CO2, O2, and pH.
      • Hypercapnia: increased arterial CO2 levels; stimulates chemoreceptors, leading to increased respiratory rate.
      • Hypocapnia: decreased arterial CO2 levels; inhibits chemoreceptors, leading to decreased respiratory rate.
    • Baroreceptor reflexes: monitor blood pressure in carotid and aortic sinuses.
      • Decreased blood pressure: stimulates respiratory centers, leading to increased respiratory minute volume.
      • Increased blood pressure: inhibits respiratory centers, leading to decreased respiratory minute volume.

    Trachea

    • The ends of each C-shaped tracheal cartilage are connected by elastic ligament and trachealis muscle
    • Trachealis muscle contraction narrows the trachea restricting airflow
    • Tracheal diameter changes are mostly controlled by sympathetic stimulation, which increases airflow
    • Tracheal cartilage is incomplete posteriorly, allowing expansion when swallowing

    Bronchi and Bronchioles

    • Bronchioles do not have cartilage, but they have thick smooth muscle
    • The sympathetic nervous system causes bronchodilation, which increases airflow
    • The parasympathetic nervous system causes bronchoconstriction, which decreases airflow
    • Extreme bronchoconstriction can occur during allergic reactions such as asthma
    • Terminal bronchioles lead to pulmonary lobules, where gas exchange occurs
    • Respiratory bronchioles are the last division of the bronchiole system

    Airflow and Diameter Changes

    • The trachea carries air from the larynx to the main bronchi in the mediastinum
    • The main bronchi, one for each lung, have complete cartilage rings
    • Lobar bronchi, three in the right lung and two in the left lung, are responsible for one lobe each
    • Segmental bronchi branch to form bronchioles
    • Bronchioles continue to branch into smaller and smaller tubes, with a decreasing diameter
    • The branching continues from bronchioles to terminal bronchioles, to respiratory bronchioles, and finally to pulmonary lobules

    Respiratory Muscles

    • Respiratory muscles involved with breathing can be either inspiratory or expiratory muscles
    • Quiet breathing involves active inhalation via inspiratory muscles and passive exhalation due to elastic recoil of tissues and gravity
    • Expiratory muscles are used to force exhalation when needed
    • The primary respiratory muscles are responsible for inhalation
    • Accessory respiratory muscles assist primary inspiratory muscles or provide active exhalation

    Inspiratory Muscles

    • Primary inspiratory muscles include the diaphragm and external intercostals
    • The diaphragm performs approximately 75% of the inspiratory movement, flattening the floor of the thoracic cavity
    • The external intercostals do ~25% of the inspiratory movement, elevating the ribs
    • Accessory inspiratory muscles include the sternocleidomastoid, scalenes, pectoralis minor, and serratus anterior, which increase the speed and amount of rib movement to move more air when needed, when tissue oxygen demand is not met by primary inspiratory muscles

    Expiratory Muscles

    • There are no primary expiratory muscles, exhalation is usually passive due to elastic recoil and gravity

    Alveolar Ventilation

    • Alveolar ventilation (VA) is the amount of air reaching the alveoli per minute
    • Some air never reaches the alveoli, remaining in the conducting portion of the lungs, which is known as anatomic dead space (VD)
    • The average anatomic dead space at rest is ~150 mL
    • Alveolar ventilation is calculated by multiplying breaths per minute by the volume of air in the alveoli
    • The volume of air in the alveoli is equal to the tidal volume (VT) minus the anatomic dead space (VD)
    • VA = f × (VT – VD)
    • When the demand for oxygen increases, both tidal volume and respiratory rate must increase

    Gas Laws

    • Gas laws govern the movement and diffusion of gas molecules
    • Boyle's law determines the direction of air movement during pulmonary ventilation
    • The atmosphere is a mixture of gases with a total atmospheric pressure at sea level of 760 mm Hg
    • Partial pressure (P) is the pressure exerted by a single gas in a mixture
    • Dalton's law states that the partial pressures of all the gases added together equal the total pressure exerted by the gas mixture

    Gas Diffusion

    • The gas mixture inside the respiratory tract varies by location
    • Inhaled air is moistened and warmed
    • In the alveoli, inhaled air mixes with air from the previous breath
    • Exhaled air mixes with air in the anatomic dead space
    • As the gas mixture varies, so do the partial pressures of its component gases
    • Henry's law states that at a given temperature, the amount of a particular gas in solution is directly proportional to the partial pressure of that gas
    • External respiration happens when blood arriving in pulmonary arteries has a lower PO2 and higher PCO2 than in alveolar air
    • Diffusion between the alveolar mixture and pulmonary capillaries increases blood PO2 (oxygen enters the blood) and decreases PCO2 (carbon dioxide leaves the blood)
    • Internal respiration happens when the PO2 of blood leaving the lungs in pulmonary veins drops slightly when it mixes with blood from capillaries around conducting passageways, but is still higher than PO2 of interstitial fluid
    • Oxygen diffuses from blood to interstitial fluid
    • The PCO2 is higher in tissues and interstitial fluid than in blood
    • Carbon dioxide diffuses from tissues into blood

    Respiratory Control Mechanisms

    • Respiratory control involves multiple levels of regulations
    • Respiratory rate and rhythm are set by the network of respiratory centers
    • Most respiratory regulation occurs outside of conscious control

    Respiratory Rhythmicity Centers

    • Pacemaker cells in the medulla oblongata generate cycles of contractions in the diaphragm
    • Paired respiratory rhythmicity centers establish the pace of respiration by adjusting pacemaker cells and coordinating other respiratory muscles
    • Each center is subdivided into two groups: dorsal respiratory group (DRG) and ventral respiratory group (VRG)
    • The DRG varies its response through input from chemoreceptors detecting O2, Co2, and pH levels in blood/CSF, and baroreceptors monitoring the stretch of the lung wall
    • The DRG is mainly concerned with inspiration, and its inspiratory center controls lower motor neurons to the primary inspiratory muscles (external intercostals, diaphragm)
    • The VRG is mainly associated with expiration and functions only when breathing demands increase and accessory respiratory muscles are involved
    • The pre-Bӧtzinger complex, located in the medulla, is essential to all forms of breathing, but it is poorly understood

    Respiratory System

    • Respiratory System Structures and Functions: This section focuses on the anatomy of the respiratory system and its roles.
    • Delicate Respiratory Exchange Surfaces Protection: The systems uses structures like mucus membranes, cilia, and macrophages to defend itself from various pathogens, debris, and other hazards.
    • Cystic Fibrosis: Cystic fibrosis is a genetic condition causing mucus buildup in the respiratory system, impacting lung function.
    • Upper Respiratory System: Includes the nose, pharynx, and larynx.
    • Pulmonary Ventilation: This process is powered by pressure changes within the pleural cavities.
    • Boyle's Law: It states that the volume of a gas is inversely proportional to the pressure exerted by the gas.
    • Thoracic Cavity Volume Changes: The diaphragm and the rib cage are key players in regulating the volume of the thoracic cavity, affecting the lungs' size and, hence, pressure.
    • Pressure Relationship During Inhalation: The thoracic cavity expansion results in increased lung volume. This decrease in internal pressure compared to external pressure leads to air movement inwards.
    • Inspiratory and Expiratory Muscles: The body uses various muscles, categorized as inspiratory or expiratory, to control breathing. Quiet breathing relies primarily on passive exhalation, whereas active exhalation requires additional muscles.
    • Primary Inspiratory Muscles: Diaphragm and external intercostals are critical for inhalation.
    • Accessory Inspiratory Muscles: Sternocleidomastoid, scalenes, pectoralis minor, and serratus anterior assist with forceful or increased ventilation needs.
    • Expiratory Muscles: There are no primary expiratory muscles; exhalation typically happens passively due to elastic recoil and gravity.
    • Oxygen Transport in Blood: The blood transports oxygen bound to hemoglobin molecules within red blood cells.
    • Hemoglobin Structure: Hemoglobin has four globular proteins, each with a heme unit, allowing binding to four oxygen molecules.
    • Carbon Monoxide Hazard: Carbon monoxide binds to heme units, preventing oxygen transport.
    • Oxygen-Hemoglobin Saturation Curve: A visual representation of the relationship between the percentage of hemoglobin with bound oxygen and partial pressure of oxygen.
    • Chemoreceptor Reflexes: These reflexes, primarily triggered by changes in CO2 levels, adjust breathing rate.
    • Hypercapnia: Elevated arterial CO2 due to insufficient breathing, stimulates chemoreceptors, leading to an increase in respiratory rate.
    • Hypocapnia: Decreased arterial CO2, often caused by rapid breathing, results in lowered breathing rate.
    • Baroreceptor Reflexes: These receptors in carotid and aortic sinuses monitor blood pressure, relaying info to the respiratory centers to adjust breathing rate accordingly.

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    Description

    Test your knowledge on the human respiratory system, focusing on lung function, anatomy, and the interaction between the heart and lungs. This quiz covers essential concepts including gas exchange, airflow pathways, and the components of both respiratory and circulatory systems.

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