Podcast
Questions and Answers
What is Respiration?
What is Respiration?
Respiration is the sequence of events that results in the exchange of oxygen and carbon dioxide between the atmosphere and the body cells.
What are the two main types of respiration?
What are the two main types of respiration?
External respiration is the exchange of gases between the ______ and the blood.
External respiration is the exchange of gases between the ______ and the blood.
lungs
Internal respiration is the exchange of gases between the blood and ______.
Internal respiration is the exchange of gases between the blood and ______.
Signup and view all the answers
What do cells utilize oxygen for?
What do cells utilize oxygen for?
Signup and view all the answers
What is the total volume of the air channels that conduct inspired air to the alveoli?
What is the total volume of the air channels that conduct inspired air to the alveoli?
Signup and view all the answers
What function do the air channels that conduct inspired air to the alveoli serve?
What function do the air channels that conduct inspired air to the alveoli serve?
Signup and view all the answers
How are dirt particles in the air caught?
How are dirt particles in the air caught?
Signup and view all the answers
The trachea and bronchi have supporting cartilage to keep airways open.
The trachea and bronchi have supporting cartilage to keep airways open.
Signup and view all the answers
The airways from the nasal cavity through the terminal bronchioles are called the conducting zone.
The airways from the nasal cavity through the terminal bronchioles are called the conducting zone.
Signup and view all the answers
The air is moistened, warmed, and filtered as it flows through the passageways.
The air is moistened, warmed, and filtered as it flows through the passageways.
Signup and view all the answers
The respiratory zone contains alveoli, tiny thin-walled sacs where gas exchange occurs.
The respiratory zone contains alveoli, tiny thin-walled sacs where gas exchange occurs.
Signup and view all the answers
What is the name of the clusters of alveoli at the end of alveolar ducts?
What is the name of the clusters of alveoli at the end of alveolar ducts?
Signup and view all the answers
Alveolar ducts are completely lined by alveoli.
Alveolar ducts are completely lined by alveoli.
Signup and view all the answers
Respiratory bronchioles contain scattered alveoli in the walls.
Respiratory bronchioles contain scattered alveoli in the walls.
Signup and view all the answers
Resistance of inspired air is affected by the diameter of the airway.
Resistance of inspired air is affected by the diameter of the airway.
Signup and view all the answers
What happens to smooth muscles surrounding the bronchioles in asthma?
What happens to smooth muscles surrounding the bronchioles in asthma?
Signup and view all the answers
Medicines can relax smooth muscles in the airways, allowing airflow.
Medicines can relax smooth muscles in the airways, allowing airflow.
Signup and view all the answers
Pulmonary arteries carry blood that is low in oxygen from the heart to the lungs.
Pulmonary arteries carry blood that is low in oxygen from the heart to the lungs.
Signup and view all the answers
Pulmonary veins transport oxygenated blood back to the heart.
Pulmonary veins transport oxygenated blood back to the heart.
Signup and view all the answers
Oxygen and carbon dioxide are exchanged between the air in the alveoli and the blood in the pulmonary capillaries.
Oxygen and carbon dioxide are exchanged between the air in the alveoli and the blood in the pulmonary capillaries.
Signup and view all the answers
What are the three main factors that efficient external respiration depends on?
What are the three main factors that efficient external respiration depends on?
Signup and view all the answers
In many regions of the respiratory membrane there is no interstitial fluid.
In many regions of the respiratory membrane there is no interstitial fluid.
Signup and view all the answers
The partial pressures of gases in the alveoli differ from those in the atmosphere.
The partial pressures of gases in the alveoli differ from those in the atmosphere.
Signup and view all the answers
98.5% of the oxygen that diffuses from the alveoli combines with hemoglobin.
98.5% of the oxygen that diffuses from the alveoli combines with hemoglobin.
Signup and view all the answers
1.5% of the oxygen that diffuses from the alveoli dissolves in plasma.
1.5% of the oxygen that diffuses from the alveoli dissolves in plasma.
Signup and view all the answers
A hemoglobin molecule can transport up to four oxygen molecules.
A hemoglobin molecule can transport up to four oxygen molecules.
Signup and view all the answers
Oxygen binding occurs in response to the high partial pressure of oxygen in the lungs.
Oxygen binding occurs in response to the high partial pressure of oxygen in the lungs.
Signup and view all the answers
Hemoglobin saturation is determined by the partial pressure of oxygen.
Hemoglobin saturation is determined by the partial pressure of oxygen.
Signup and view all the answers
When pH decreases, the oxygen-hemoglobin dissociation curve shifts to the right, increasing oxygen unloading.
When pH decreases, the oxygen-hemoglobin dissociation curve shifts to the right, increasing oxygen unloading.
Signup and view all the answers
Oxygen binding capacity of hemoglobin increases with temperature decrease and pH increase.
Oxygen binding capacity of hemoglobin increases with temperature decrease and pH increase.
Signup and view all the answers
93% of the carbon dioxide that diffuses from the tissue cells diffuses into red blood cells.
93% of the carbon dioxide that diffuses from the tissue cells diffuses into red blood cells.
Signup and view all the answers
7% of the carbon dioxide that diffuses from the tissue cells dissolves in plasma.
7% of the carbon dioxide that diffuses from the tissue cells dissolves in plasma.
Signup and view all the answers
Carbonic anhydrase makes the conversion of carbon dioxide to bicarbonate ions 300 times faster.
Carbonic anhydrase makes the conversion of carbon dioxide to bicarbonate ions 300 times faster.
Signup and view all the answers
The major part of carbon dioxide that enters the red blood cells undergoes conversion to bicarbonate ions.
The major part of carbon dioxide that enters the red blood cells undergoes conversion to bicarbonate ions.
Signup and view all the answers
Of the total carbon dioxide, 23% binds to the globin portion of the hemoglobin molecule to form carbaminohemoglobin.
Of the total carbon dioxide, 23% binds to the globin portion of the hemoglobin molecule to form carbaminohemoglobin.
Signup and view all the answers
Carbaminohemoglobin forms in regions of high partial pressure of carbon dioxide.
Carbaminohemoglobin forms in regions of high partial pressure of carbon dioxide.
Signup and view all the answers
In regions with high partial pressure of carbon dioxide, carbon dioxide binds with water to form carbonic acid.
In regions with high partial pressure of carbon dioxide, carbon dioxide binds with water to form carbonic acid.
Signup and view all the answers
Carbonic acid dissociates into hydrogen ions and bicarbonate ions.
Carbonic acid dissociates into hydrogen ions and bicarbonate ions.
Signup and view all the answers
Hydrogen ions bind to hemoglobin.
Hydrogen ions bind to hemoglobin.
Signup and view all the answers
Chloride shift occurs when bicarbonate ions exchange for chloride ions to maintain electrical neutrality.
Chloride shift occurs when bicarbonate ions exchange for chloride ions to maintain electrical neutrality.
Signup and view all the answers
The brain is the most sensitive organ to oxygen deficiency.
The brain is the most sensitive organ to oxygen deficiency.
Signup and view all the answers
Cyanosis is a dark (blue) color of nails, lips, ears, and areas where the skin is thin.
Cyanosis is a dark (blue) color of nails, lips, ears, and areas where the skin is thin.
Signup and view all the answers
Cyanosis occurs when the amount of desoxygenated hemoglobin in the capillaries exceeds 50 g/l.
Cyanosis occurs when the amount of desoxygenated hemoglobin in the capillaries exceeds 50 g/l.
Signup and view all the answers
The respiratory center is located in the pons and medulla oblongata of the brain.
The respiratory center is located in the pons and medulla oblongata of the brain.
Signup and view all the answers
The inspiratory area of the respiratory center stimulates the phrenic nerve, leading to diaphragm contraction.
The inspiratory area of the respiratory center stimulates the phrenic nerve, leading to diaphragm contraction.
Signup and view all the answers
Normal breathing rate in adults averages between 12 and 20 times per minute.
Normal breathing rate in adults averages between 12 and 20 times per minute.
Signup and view all the answers
The breathing rate is higher in children.
The breathing rate is higher in children.
Signup and view all the answers
The basic rhythm of breathing is controlled by respiratory centers located in the medulla and pons of the brainstem.
The basic rhythm of breathing is controlled by respiratory centers located in the medulla and pons of the brainstem.
Signup and view all the answers
The inspiratory center sets the rhythm of breathing by automatically initiating inspiration.
The inspiratory center sets the rhythm of breathing by automatically initiating inspiration.
Signup and view all the answers
The normal resting breathing rate is between 12 and 15 breaths per minute.
The normal resting breathing rate is between 12 and 15 breaths per minute.
Signup and view all the answers
The inspiratory center sends nerve impulses to the diaphragm and external intercostal muscles that contract for 2 seconds, initiating inspiration.
The inspiratory center sends nerve impulses to the diaphragm and external intercostal muscles that contract for 2 seconds, initiating inspiration.
Signup and view all the answers
Central and peripheral chemoreceptors detect oxygen, carbon dioxide, and pH levels.
Central and peripheral chemoreceptors detect oxygen, carbon dioxide, and pH levels.
Signup and view all the answers
Mechanoreceptors in the lungs detect changes in lung volume and pressure.
Mechanoreceptors in the lungs detect changes in lung volume and pressure.
Signup and view all the answers
Higher brain centers can influence breathing in response to pain and emotions.
Higher brain centers can influence breathing in response to pain and emotions.
Signup and view all the answers
Temperature can influence breathing rate.
Temperature can influence breathing rate.
Signup and view all the answers
Peripheral chemoreceptors are located in the aortic bodies and carotid bodies.
Peripheral chemoreceptors are located in the aortic bodies and carotid bodies.
Signup and view all the answers
Peripheral chemoreceptors monitor PCO2, pH, and PO2 of arterial blood.
Peripheral chemoreceptors monitor PCO2, pH, and PO2 of arterial blood.
Signup and view all the answers
Information from the peripheral chemoreceptors travels to the respiratory centers via the vagus and glossopharyngeal nerves.
Information from the peripheral chemoreceptors travels to the respiratory centers via the vagus and glossopharyngeal nerves.
Signup and view all the answers
Central chemoreceptors in the medulla monitor the pH associated with CO2 levels in the cerebrospinal fluid in the fourth ventricle.
Central chemoreceptors in the medulla monitor the pH associated with CO2 levels in the cerebrospinal fluid in the fourth ventricle.
Signup and view all the answers
Central chemoreceptors synapse directly with the respiratory centers.
Central chemoreceptors synapse directly with the respiratory centers.
Signup and view all the answers
As CO2 increases, the number of hydrogen ions increases, lowering the pH.
As CO2 increases, the number of hydrogen ions increases, lowering the pH.
Signup and view all the answers
Central chemoreceptors respond to pH changes caused by blood PCO2.
Central chemoreceptors respond to pH changes caused by blood PCO2.
Signup and view all the answers
Aortic and carotid bodies detect pH, PO2, and PCO2 of arterial blood.
Aortic and carotid bodies detect pH, PO2, and PCO2 of arterial blood.
Signup and view all the answers
Pain and strong emotions, such as fear and anxiety, act by way of the hypothalamus to stimulate or inhibit respiratory centers.
Pain and strong emotions, such as fear and anxiety, act by way of the hypothalamus to stimulate or inhibit respiratory centers.
Signup and view all the answers
Laughing and crying can significantly alter ventilation.
Laughing and crying can significantly alter ventilation.
Signup and view all the answers
Dust, smoke, noxious fumes, excess mucus, and other irritants stimulate receptors in the airways.
Dust, smoke, noxious fumes, excess mucus, and other irritants stimulate receptors in the airways.
Signup and view all the answers
This initiates protective reflexes, such as coughing and sneezing, which remove irritants from the airway.
This initiates protective reflexes, such as coughing and sneezing, which remove irritants from the airway.
Signup and view all the answers
By sending signals from the cerebral cortex to respiratory muscles, we can voluntarily change our breathing rate and depth when holding our breath, speaking, or singing.
By sending signals from the cerebral cortex to respiratory muscles, we can voluntarily change our breathing rate and depth when holding our breath, speaking, or singing.
Signup and view all the answers
Chemoreceptor input to the respiratory centers will eventually override conscious control and force you to breathe.
Chemoreceptor input to the respiratory centers will eventually override conscious control and force you to breathe.
Signup and view all the answers
Stretch receptors in the visceral pleura and large airways send inhibitory signals to the inspiratory center during very deep inspirations, protecting against excessive stretching of the lungs.
Stretch receptors in the visceral pleura and large airways send inhibitory signals to the inspiratory center during very deep inspirations, protecting against excessive stretching of the lungs.
Signup and view all the answers
This is known as the Hering-Breuer reflex.
This is known as the Hering-Breuer reflex.
Signup and view all the answers
When airflow is restricted, the resulting low PO2 causes the local arterioles to vasoconstrict.
When airflow is restricted, the resulting low PO2 causes the local arterioles to vasoconstrict.
Signup and view all the answers
Blood is redirected to alveoli with a higher airflow and more oxygen.
Blood is redirected to alveoli with a higher airflow and more oxygen.
Signup and view all the answers
In regions with high airflow compared to their blood supply, the resulting high PO2 causes the local arterioles to vasodilate.
In regions with high airflow compared to their blood supply, the resulting high PO2 causes the local arterioles to vasodilate.
Signup and view all the answers
This brings more blood to the alveoli, allowing the blood to pick up the abundant oxygen.
This brings more blood to the alveoli, allowing the blood to pick up the abundant oxygen.
Signup and view all the answers
Study Notes
Respiration
- Respiration is a sequence of events resulting in the exchange of oxygen and carbon dioxide between the atmosphere and body cells.
External Respiration
- Occurs every 3 to 5 seconds
- Nerve impulses stimulate the breathing process (ventilation)
- Moves air in and out of the lungs
- Exchange of gases between the lungs and the blood
Internal Respiration
- Exchange of gases between the blood and tissue cells
Cellular Respiration
- Cells utilize oxygen for their specific activities
Sites of Gas Exchange
- External respiration:
- CO2 diffuses from pulmonary capillaries into alveoli
- O2 diffuses from alveoli into pulmonary capillaries
- Internal respiration:
- O2 diffuses from systemic capillaries into cells
- CO2 diffuses from cells into systemic capillaries
Internal Respiration: O2 and CO2 Exchange
-
Partial pressures of oxygen (PO2) and carbon dioxide (PCO2) drive gas exchange.
-
Gas exchange continues until equilibrium is reached
-
PO2 in oxygenated blood: 100 mm Hg
-
PCO2 in oxygenated blood: 40 mm Hg
-
PO2 in tissue cells: 40 mm Hg
-
PCO2 in tissue cells: 45 mm Hg
Overview: Respiratory System Organs
- Includes the nasal cavity, external nares (nostrils), pharynx, trachea, right primary bronchus, right lung, diaphragm, larynx, left primary bronchus, and left lung.
- Larynx contains vocal cords separating upper and lower respiratory tracts.
Air Conducting Passages
- Upper respiratory tract: nose, pharynx, larynx
- Lower respiratory tract: trachea, bronchial tree, lungs (alveoli)
Anatomic Dead Space
- Total volume of air channels that conduct inspired air to the alveoli approximately 150 ml
- Does not take part in gas exchange
- Functions as an air conduit, humidifying and warming air before reaching alveoli
- Includes structures like the mouth, nose, pharynx, trachea, and bronchi
Cleansing of the Inspired Air
- Dirt particles in the air are trapped by mucus in nasal and pharyngeal cavities, trachea, and bronchial tree.
- Particles are then phagocytosed or moved towards the pharynx by cilia of the epithelium
Bronchial Tree
- Trachea and bronchi have supporting cartilage maintaining open airways.
- Bronchiole walls contain more smooth muscle for airflow regulation.
- Airways from the nasal cavity to terminal bronchioles are the conducting zone.
- Air is moistened, warmed, and filtered flowing through these passageways.
Respiratory Zone
- Respiratory zone contains alveoli, tiny thin-walled sacs for gas exchange.
- Alveolar ducts end in clusters of alveoli called alveolar sacs.
- Respiratory bronchioles contain scattered alveoli within walls.
Resistance within the Airways
- Gas molecules encounter resistance when striking airway walls.
- Airway diameter affects resistance.
- Smooth muscle surrounding bronchioles constrict in asthma narrowing the airways
Alveoli and Pulmonary Capillaries
- Pulmonary arteries carry deoxygenated blood from the heart to the lungs.
- These blood vessels form dense networks of capillaries surrounding each alveolus.
- Oxygen and carbon dioxide exchange between air in alveoli and blood in pulmonary capillaries.
- Blood leaves via pulmonary veins carrying oxygenated blood back to the heart.
Structure of an Alveolus
- Alveolar macrophages remove debris and microbes from the alveolus' inner surface.
- Simple squamous epithelium (Type I cells) and surfactant-secreting cells (Type II cells) form the alveolus' inner walls.
Role of Surfactant
- Water in the alveolar fluid creates surface tension.
- Surfactant, a mixture of phospholipids and lipoproteins, lowers the alveolar fluid's surface tension.
- Facilitating expansion of alveoli and preventing them from collapsing during exhalation
Factors influencing External Respiration
- Depends on three main factors:
- Surface area and structure of the respiratory membrane
- Partial pressure gradients
- Matching alveolar airflow to pulmonary capillary blood flow
Structure of the Respiratory Membrane
- Respiratory membrane averages 0.5 µm in width
- In many regions, there is no interstitial fluid.
- Oxygen and carbon dioxide can easily diffuse across the membrane.
External Respiration: Partial Pressures
- Partial pressures of gases in alveoli differ from the atmosphere.
- This difference is due to:
- Humidification of inhaled air
- Gas exchange between alveoli and pulmonary capillaries
- Mixing of new and old air
External Respiration: Loading O2
- O2 diffuses from alveoli into the blood (high PO2 in alveoli, low PO2 in blood)
External Respiration: Unloading CO2
- CO2 diffuses from the blood into the alveoli (high PCO2 in blood, low PCO2 in alveoli)
O2 Transport
- Of the O2 that diffuses from the alveoli:
- 98.5% combines with hemoglobin
- 1.5% dissolves in plasma
Hemoglobin
- When 4 O2s are bound to hemoglobin, it is 100% saturated.
- Fewer O2s result in partial saturation.
- Oxygen binding occurs in response to high PO2 in the lungs.
Oxygen-Hemoglobin Dissociation Curve
- Hemoglobin saturation is determined by partial pressure of oxygen.
Factors Altering Hemoglobin Saturation
- When pH decreases, the curve shifts right (increased O2 unloading). Similar shifts occur in response to: Carbon dioxide and temperature.
Oxygen Binding and Transport in the Blood
- Oxygen binding to hemoglobin is oxygenation.
- Pressure of oxygen in arterial blood is ~95 mm Hg; in venous blood is ~40 mm Hg.
- Oxygen dissociation curve illustrates relationship between oxygen pressure in the blood and hemoglobin saturation.
- Oxygen binding capacity of hemoglobin increases with decreased temperature and increased pH e.g., in tissues
CO2 Transport
- Of the CO2 that diffuses from the tissue cells:
- 93% diffuses into RBCs
- 70% of CO2 is converted to bicarbonate ions
- 23% combines with hemoglobin to form carbaminohemoglobin.
- 7% dissolves in plasma
Carbon Dioxide Transport in the Blood
- Major part enters RBCs and is converted to bicarbonate (HCO3−).
- Carbonic anhydrase accelerates this conversion threefold.
- Pressure of carbon dioxide in arterial blood ≈ 40 mm Hg, in venous blood ≈ 46 mm Hg.
Hypoxia – Oxygen Deficit in the Tissues
- Hypoxia: oxygen deficit in tissues
- Hypoxic hypoxia: reduced oxygen content in the air
- Anemic hypoxia: not enough oxygen bound to blood (reduced oxygen capacity)
- Histotoxic hypoxia: tissues cannot use oxygen
- Ischemic hypoxia: decreased blood supply to tissues
- Brain is most sensitive organ
Cyanosis
- Dark (blue) coloration of nails, lips, ears, and thin-skinned areas.
- Occurs when deoxygenated hemoglobin in capillaries exceeds 50 g/l.
Respiratory Center
- Pons and medulla oblongata of the brain control the rate and depth of breathing.
- Inspiratory area → Phrenic nerve → Diaphragm contraction
- Normal breathing rate in adults is between 12 and 20 times per minute, higher in children (≈40/min)
Inspiratory Center
- The basic rhythm of breathing is controlled by respiratory centers in the brainstem (medulla and pons).
- Inspiratory center (dorsal respiratory group) sets the rhythm by automatically initiating inspiration.
Quiet Inspiration: Muscle Contraction
- Diaphragm and external intercostal muscles contract
- Increasing the volume decreases the pressure in the thoracic cavity.
- Diaphragm flattens and moves inferiorly.
- External intercostal muscles elevate the rib cage and move the sternum anteriorly.
Quiet Expiration: Muscle Relaxation
- Diaphragm and external intercostal muscles relax.
- Elastic lungs and thoracic wall recoil inward.
- This decreases the volume and increases pressure in the thoracic cavity.
- Diaphragm moves superiorly
- External intercostal muscles relax, rib cage, and sternum return to resting positions
Respiratory Volumes
- TV (tidal volume): air volume inspired and expired during quiet breathing (~500 ml)
- IRV (inspiratory reserve volume): additional air inspired after quiet inspiration (~2.5 L)
- ERV (expiratory reserve volume): additional air expired after quiet expiration (~1.5 L)
- VC (vital capacity): maximum air expired after maximal inspiration (TV + IRV + ERV)
- RV (residual volume): air remaining in lungs after maximal expiration (TLV - VC)
- TLV (total lung volume): TV + IRV + ERV + RV
Other Factors Influencing Ventilation
- Pain and strong emotions (through hypothalamic influence)
- Pulmonary irritants (dust, smoke, fumes, etc.) trigger coughing and sneezing reflexes.
- Voluntary control (can vary breath rate and depth)
- Lung hyperinflation is detected by stretch receptors in the visceral pleura and large airways and send inhibitory signals to inspiratory area, to protect lungs against excessive stretching (Hering-Breuer reflex).
Ventilation-Perfusion Coupling
- When airflow restricted (low PO2), local arterioles vasoconstrict.
- Blood redirected to alveoli with higher airflow and more available O2.
- In regions with high airflow (high PO2), local arterioles vasodilate; more blood delivered to alveoli to pick up available O2.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
