TA - Respiratory Systems Quiz
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Questions and Answers

What mechanism allows for efficient oxygenation of blood in gills?

  • Lateral flow
  • Counter current flow (correct)
  • Parallel flow
  • Globular flow

    • What unique feature of birds allows for continuous gas exchange during expiration?

  • Air sacs and parabronchi (correct)
  • Lungs with alveoli
  • Pneumatized bones
  • Diaphragm and ribcage

    • At what altitude does the partial pressure of oxygen drop to nearly half of that at sea level?

  • 6000 m (correct)
  • 3000 m
  • 4000 m
  • 5000 m

    • Which center in the brain controls the rate and depth of breathing?

    <p>Pneumotaxic centre in the pons</p> Signup and view all the answers

    What substance is released as a byproduct during the oxidation of food materials such as glucose?

    <p>Carbon dioxide</p> Signup and view all the answers

    Which type of animal supplies oxygen directly to each cell through a system of tracheae?

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

    What typically forces a human to breathe after holding their breath?

    <p>Build-up of carbon dioxide</p> Signup and view all the answers

    What component found in the muscles of certain aquatic mammals increases their affinity for oxygen?

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

    What is the primary cause of asbestosis?

    <p>Exposure to asbestos dust</p> Signup and view all the answers

    Which disorder is caused by long term exposure to silica dust?

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

    What is a possible outcome of inhaling iron particles over time?

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

    Which respiratory disorder is commonly associated with coal mining?

    <p>Black-lung disease</p> Signup and view all the answers

    Which of the following statements best describes siderosis?

    <p>It is a form of pneumoconiosis due to inhaling iron particles.</p> Signup and view all the answers

    What is the main purpose of the respiratory process known as breathing?

    <p>Exchange of O2 and CO2</p> Signup and view all the answers

    Which of the following best describes anaerobic respiration?

    <p>Incomplete breakdown of organic molecules</p> Signup and view all the answers

    Where does the process of internal respiration take place?

    <p>Inside living cells</p> Signup and view all the answers

    Which structure in the human respiratory system is primarily responsible for sound production?

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

    How do aquatic arthropods primarily exchange gases?

    <p>Using gills</p> Signup and view all the answers

    What is the function of the nasal chambers in the human respiratory system?

    <p>Air conditioning and smell detection</p> Signup and view all the answers

    What structure prevents food from entering the larynx during swallowing?

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

    What characterizes the respiratory system of mammals?

    <p>Well developed lungs</p> Signup and view all the answers

    Which of the following statements is true regarding the bronchi and bronchioles?

    <p>They are branching structures of the pulmonary tree</p> Signup and view all the answers

    What is the main cellular outcome of aerobic respiration?

    <p>36ATP per glucose</p> Signup and view all the answers

    Which part of the larynx is responsible for producing a high pitch sound?

    <p>True vocal cords</p> Signup and view all the answers

    What is the role of the pleural fluid in the lungs?

    <p>Reducing friction between lung surfaces</p> Signup and view all the answers

    What type of respiration do yeast undergo in the absence of oxygen?

    <p>Anaerobic respiration</p> Signup and view all the answers

    Which component prevents the trachea from collapsing?

    <p>C-shaped cartilage rings</p> Signup and view all the answers

    What is the primary mechanism for oxygen transport in red blood cells?

    <p>Oxygen is bound to haemoglobin</p> Signup and view all the answers

    How much of oxygen is typically delivered to tissues by 100 ml of oxygenated blood?

    <p>5 ml</p> Signup and view all the answers

    What change occurs in haemoglobin's affinity for oxygen at low pO2 levels?

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

    Which factor does NOT influence the binding of oxygen with haemoglobin?

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

    What is the primary form in which carbon dioxide is transported in the blood?

    <p>As bicarbonates</p> Signup and view all the answers

    What does the oxyhaemoglobin dissociation curve illustrate?

    <p>The relationship between haemoglobin saturation and pO2</p> Signup and view all the answers

    Which statement best describes the Bohr Effect?

    <p>Increased pCO2 decreases the affinity of haemoglobin for oxygen</p> Signup and view all the answers

    What percentage of carbon dioxide is transported in dissolved form within plasma?

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

    What happens to oxyhaemoglobin in tissues with low pO2?

    <p>It dissociates into haemoglobin and oxygen</p> Signup and view all the answers

    What occurs when the pCO2 levels rise in the blood?

    <p>The affinity of haemoglobin for oxygen decreases</p> Signup and view all the answers

    Which of the following statements about bicarbonate is true?

    <p>Bicarbonate is formed in red blood cells through the action of carbonic anhydrase</p> Signup and view all the answers

    During vigorous exercise, what percentage of oxygen may be unloaded to tissues?

    <p>62 percent</p> Signup and view all the answers

    What adaptation allows haemoglobin to effectively manage oxygen and carbon dioxide transport?

    <p>Haemoglobin's amphoteric properties</p> Signup and view all the answers

    What role does hemoglobin play in buffering H+ ions during gas exchange?

    <p>It acts as a high capacity buffer.</p> Signup and view all the answers

    What occurs during the chloride shift in red blood cells?

    <p>Chloride ions enter the RBCs while bicarbonate ions exit.</p> Signup and view all the answers

    Which center in the brain is primarily responsible for regulating respiratory rhythm?

    <p>Respiratory Rhythm Center</p> Signup and view all the answers

    How does an increase in CO2 and H+ concentration affect breathing?

    <p>It activates the respiratory centers to increase breathing.</p> Signup and view all the answers

    What is the primary effect of the pneumotaxic center on respiration?

    <p>It reduces the duration of inspiration.</p> Signup and view all the answers

    What does the residual volume represent in respiratory volumes?

    <p>The volume of air that cannot be expelled from the lungs.</p> Signup and view all the answers

    Which respiratory capacity includes tidal volume and inspiratory reserve volume?

    <p>Inspiratory Capacity</p> Signup and view all the answers

    What is a primary symptom of asthma?

    <p>Wheezing and difficulty in breathing</p> Signup and view all the answers

    Which of the following is a major cause of emphysema?

    <p>Smoking tobacco</p> Signup and view all the answers

    What is included in the definition of vital capacity?

    <p>Tidal volume, inspiratory reserve volume, and expiratory reserve volume.</p> Signup and view all the answers

    How does pneumonia affect gas exchange in the lungs?

    <p>Causes inflammation and mucus accumulation in alveoli.</p> Signup and view all the answers

    Which of the following components reflects the normal range of tidal volume?

    <p>350 mL to 500 mL</p> Signup and view all the answers

    What is the significance of histidine in hemoglobin's function as a buffer?

    <p>It provides a site for proton binding.</p> Signup and view all the answers

    What is the primary function of the conducting part of the respiratory system?

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

    What role does the diaphragm play during inspiration?

    <p>It creates a negative pressure in the lungs</p> Signup and view all the answers

    Which part of the respiratory system is primarily involved in gas exchange?

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

    In which circumstance does expiration primarily occur?

    <p>When intra-pulmonary pressure exceeds atmospheric pressure</p> Signup and view all the answers

    What is one factor that affects the rate of gas diffusion across the respiratory membrane?

    <p>Thickness of the diffusion membrane</p> Signup and view all the answers

    What is primarily responsible for creating pressure gradients necessary for breathing?

    <p>Changes in thoracic and pulmonary volumes</p> Signup and view all the answers

    Which gas has a higher diffusion rate due to greater solubility in the pulmonary membrane?

    <p>Carbon dioxide</p> Signup and view all the answers

    Which muscles are primarily involved in forced expiration?

    <p>Internal inter-costals and lateral abdominal muscles</p> Signup and view all the answers

    What is the typical respiratory rate for a healthy human adult?

    <p>12-16 breaths/minute</p> Signup and view all the answers

    How is the volume of air involved in breathing typically measured?

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

    What anatomical structure forms the lower boundary of the thoracic cavity?

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

    What describes the process of diffusion in the exchange of gases?

    <p>Occurs along a concentration gradient</p> Signup and view all the answers

    Which sequence correctly describes the order of respiration steps?

    <p>Breathing, diffusion, transport, utilization</p> Signup and view all the answers

    What anatomical feature best ensures that the thoracic cavity remains air-tight?

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

    What process is primarily responsible for releasing energy from food molecules?

    <p>Catabolic metabolism</p> Signup and view all the answers

    How do insects and some arthropods deliver oxygen to their cells?

    <p>Via tracheae and tracheoles</p> Signup and view all the answers

    What role does the diaphragm play in respiration for mammals?

    <p>It assists in inhalation by contracting</p> Signup and view all the answers

    What happens to the partial pressure of oxygen as altitude increases?

    <p>It decreases, dropping to nearly half at 6000 m</p> Signup and view all the answers

    What substance is formed as a harmful byproduct during cellular metabolism?

    <p>Carbon Dioxide</p> Signup and view all the answers

    What helps control the homeostasis of oxygen and carbon dioxide levels?

    <p>Respiratory centre</p> Signup and view all the answers

    What adaptation allows the elephant seal to remain underwater for extended periods?

    <p>High affinity myoglobin in muscles</p> Signup and view all the answers

    What phenomenon is likely to occur when someone ascends to high altitudes without proper acclimatization?

    <p>Altitude sickness</p> Signup and view all the answers

    What is asbestosis primarily caused by?

    <p>Chronic exposure to asbestos dust</p> Signup and view all the answers

    Which disorder is associated with long term exposure to silica dust?

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

    Siderosis can cause which of the following disorders?

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

    What is the primary cause of black-lung disease?

    <p>Inhalation of coal dust</p> Signup and view all the answers

    Which of the following is NOT a type of siderosis?

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

    What is the primary function of the conducting part of the respiratory system?

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

    Which structure contributes to increasing the thoracic volume during inspiration?

    <p>Diaphragm and external inter-costal muscles</p> Signup and view all the answers

    What drives the process of expiration in the respiratory system?

    <p>Relaxation of the diaphragm and inter-costal muscles</p> Signup and view all the answers

    What factor has the greatest impact on the rate of diffusion of gases across the respiratory membrane?

    <p>Surface area and partial pressure gradient</p> Signup and view all the answers

    What entails the diffusion of oxygen from the alveoli to the blood?

    <p>Simple diffusion based on concentration gradient</p> Signup and view all the answers

    Which component of the respiratory system is primarily responsible for the exchange of gases?

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

    What is the role of the pleural fluid in the respiratory system?

    <p>Provide lubrication and reduce friction between lung surfaces</p> Signup and view all the answers

    Which factor does NOT influence the binding of oxygen to hemoglobin?

    <p>Chlorine concentration</p> Signup and view all the answers

    Why is the alveolar wall structure important for gas exchange?

    <p>It is made up of thin squamous epithelium allowing rapid diffusion.</p> Signup and view all the answers

    What is the typical respiratory rate of a healthy human at rest?

    <p>12-16 breaths per minute</p> Signup and view all the answers

    What is primarily responsible for the creation of pressure differences that facilitate breathing?

    <p>Contraction of diaphragm and inter-costal muscles</p> Signup and view all the answers

    Which respiratory process is considered an active process?

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

    In what way does carbon dioxide diffusion differ from oxygen diffusion?

    <p>CO2 has a higher solubility than O2 in the respiratory membrane.</p> Signup and view all the answers

    What is the primary distinction between breathing and respiration?

    <p>Respiration includes the chemical breakdown of food.</p> Signup and view all the answers

    Which structure is responsible for preventing food from entering the trachea?

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

    Which type of respiration yields the most energy?

    <p>Aerobic respiration</p> Signup and view all the answers

    What is the role of the trachea in the respiratory system?

    <p>Air passageway to the lungs</p> Signup and view all the answers

    How do earthworms primarily exchange gases?

    <p>By diffusion over their entire body surface</p> Signup and view all the answers

    Which component is NOT part of the structure of the larynx?

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

    What is the function of the pleural fluid in the lungs?

    <p>Reduces friction on lung surfaces</p> Signup and view all the answers

    Which type of respiration occurs in organisms like yeast in the absence of oxygen?

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

    What structure in the respiratory system aids in sound production?

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

    Which respiratory organ is primarily used for gas exchange in aquatic arthropods?

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

    What part of the nasal chambers is responsible for filtering dust particles?

    <p>Vestibular part</p> Signup and view all the answers

    Which type of cartilage is found in the wall of the trachea?

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

    What is the initial structure through which inhaled air enters the human respiratory system?

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

    During which respiratory phase does gas exchange specifically take place in the lungs?

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

    What primarily triggers the regulation of respiratory rhythm?

    <p>Neural signals from the respiratory centers</p> Signup and view all the answers

    Which volume specifically refers to the air remaining in the lungs after forcible expiration?

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

    What role does carbon dioxide play in the respiratory process?

    <p>Stimulates breathing when levels are high</p> Signup and view all the answers

    What is the primary mechanism by which bicarbonate ions move out of red blood cells?

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

    Which statement best describes the relationship between hemoglobin and hydrogen ions?

    <p>Hemoglobin can buffer hydrogen ions but does not change its structure</p> Signup and view all the answers

    What is the primary mechanism through which oxygen is transported in the blood?

    <p>Bound to hemoglobin</p> Signup and view all the answers

    How does the partial pressure of oxygen (pO2) affect the binding of oxygen to hemoglobin?

    <p>Higher pO2 promotes oxygen binding to hemoglobin</p> Signup and view all the answers

    Which respiratory volume can be utilized to gauge lung function and potential disorders?

    <p>Vital Capacity</p> Signup and view all the answers

    What effect does the pneumotaxic center have on breathing?

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

    What happens to the oxyhemoglobin in tissues with low pO2 levels?

    <p>It dissociates into hemoglobin and oxygen</p> Signup and view all the answers

    Which factor decreases the affinity of hemoglobin for oxygen according to the Bohr Effect?

    <p>Increased pCO2</p> Signup and view all the answers

    What defines the difference between Chronic Obstructive Pulmonary Diseases (COPDs)?

    <p>They cause airway remodeling over time</p> Signup and view all the answers

    What percentage of carbon dioxide is typically transported as bicarbonate in the blood?

    <p>70%</p> Signup and view all the answers

    How is the connection between the respiratory rhythm center and the chemo-sensitive area significant?

    <p>They monitor and adjust for changes in CO2 and H+ levels</p> Signup and view all the answers

    Which condition favors the formation of oxyhemoglobin in the alveoli?

    <p>High pO2 and low pCO2</p> Signup and view all the answers

    Which condition is characterized by inflammation and increased mucus production in bronchi?

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

    What does the term 'Inspiratory Capacity' refer to?

    <p>Maximum air a person can inhale after normal expiration</p> Signup and view all the answers

    What is the primary way in which carbon dioxide is transported in the blood?

    <p>As bicarbonate</p> Signup and view all the answers

    At what partial pressure of oxygen (pO2) is hemoglobin typically around 75% saturated in resting tissues?

    <p>40 mmHg</p> Signup and view all the answers

    Which of the following is a characteristic symptom of emphysema?

    <p>Decreased lung surface area for gas exchange</p> Signup and view all the answers

    Which statement accurately describes the oxygen-hemoglobin dissociation curve?

    <p>It illustrates the relationship between oxygen saturation and pO2</p> Signup and view all the answers

    Which gas reaction occurs at the alveolar site where pCO2 is low?

    <p>Release of oxygen and water</p> Signup and view all the answers

    Which gas primarily drives the loading and unloading of oxygen in hemoglobin?

    <p>Carbon dioxide</p> Signup and view all the answers

    What best describes the role of chloride ions during the chloride shift?

    <p>They balance negative charges as bicarbonate ions diffuse out</p> Signup and view all the answers

    What role does hemoglobin serve due to its amphoteric nature?

    <p>Regulates blood pH through acid-base reactions</p> Signup and view all the answers

    During vigorous exercise, what is the maximum percentage of oxygen that may be unloaded to the tissues?

    <p>62%</p> Signup and view all the answers

    What characterizes the blood transport of carbon dioxide as carbamino compounds?

    <p>It occurs when pO2 is low</p> Signup and view all the answers

    What impact does a rise in pCO2 have on blood pH?

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

    Study Notes

    Respiration: Energy Release and Oxygen Utilization

    • Respiration is a catabolic process where energy is released through the oxidation of food.
    • Oxygen is used to produce 'metabolic water,' a byproduct of calorie burning.
    • 'Counter-current flow' in gills ensures efficient oxygenation of blood.
    • Birds have 'air sacs' and 'parabronchi' for continuous gas exchange, even during exhalation.
    • 'Tracheate animals' like insects have tracheae and tracheoles to deliver oxygen directly to cells, enabling high activity levels.
    • At high altitudes (around 6000m), oxygen levels are significantly reduced, leading to 'mountain sickness'.
    • The ribcage and diaphragm aid mammals in breathing more effectively.
    • Oxygen and carbon dioxide homeostasis are controlled by the respiratory center.
    • Inhalation and exhalation are regulated by the medulla oblongata.
    • The pneumotaxic center in the pons controls the rate and depth of breathing.
    • Elephant seals can stay submerged for up to two hours due to myoglobin in their muscles, which has a higher affinity for oxygen.

    Cellular Respiration

    • All living cells require a constant energy supply for metabolic activities.
    • Energy is produced by the oxidation of digested micromolecules like glucose, amino acids, and fatty acids.
    • These molecules are transported to cells via the circulatory system.
    • Oxygen is used by organisms to break down stored food materials (glucose, fatty acids).
    • Carbon dioxide (CO2), a byproduct of metabolism, is harmful as it dissolves in water to form carbonic acid, lowering blood pH and disrupting homeostasis.
    • The body requires continuous oxygen supply and CO2 removal.

    Overview of Respiration

    • The process of exchanging oxygen from the environment (air or water) with CO2 produced by cells is called 'breathing.'
    • Gaseous exchange, including the entry of oxygen and exit of CO2, is often called 'external respiration' or 'ventilation.'
    • The chemical breakdown of food materials to generate energy is referred to as 'respiration.'
    • Because this chemical breakdown occurs inside the cells of all organisms, it's known as 'internal respiration' or 'cellular respiration.'

    Types of Respiration

    • Anaerobic respiration: Incomplete breakdown of organic molecules, yielding less energy. Occurs in the absence of oxygen in organisms like yeast, bacteria, and muscles under certain conditions.
      • C6H12O6 → 2CO2 + 2C2H5OH (ethanol) + 2ATP
      • C6H12O6 → 2C3H6O3 (lactic acid) + 2ATP
    • Aerobic respiration: Complete breakdown of organic molecules, yielding more energy in the presence of oxygen.
      • C6H12O6 + 6H2O + 6O2 → 6CO2 + 12H2O + 36ATP

    Respiratory Organs in Animals

    • Respiration mechanisms vary depending on animal habitat and organization.
    • Protozoans and simpler invertebrates (sponges, cnidarians, flatworms) exchange gases through simple diffusion across their body surface.
    • Earthworms use their moist body wall.
    • Insects have a tracheal system for air transport.
    • Spiders and scorpions have 'book lungs' for breathing air.
    • Aquatic arthropods and molluscs have gills for gas exchange.
    • Terrestrial organisms like reptiles, birds, and mammals breathe using lungs.
    • Amphibians like frogs use both moist skin and lungs for respiration.
    • Mammals have a well-developed respiratory system.

    Human Respiratory System

    • Consists of the following structures:
      • External Nostrils (External Nares): Openings above the upper lip leading to nasal chambers.
      • Nasal Chambers: Located above the palate, separated by a nasal septum. Divided into three parts:
        • Vestibular part: Contains hair and sebaceous glands to filter dust.
        • Respiratory part: Conditioning inhaled air, supported by turbinals (conchae).
        • Olfactory part: Lined with olfactory epithelium for smell detection.
      • Naso-pharynx: Connects nasal chambers to the nasopharynx (upper portion of the pharynx).
      • Larynx: Cartilaginous box called the voice box.
        • Cartilages: Nine cartilages support the larynx:
          • Unpaired: Thyroid, cricoid, epiglottis
          • Paired: Corniculate (cartilages of Santorini), arytenoids, cuneiform
        • Epiglottis: Cartilaginous flap preventing food from entering the larynx.
        • Vocal Cords: Elastic fibers connecting thyroid and arytenoid cartilages.
          • True vocal cords: Produce sound.
          • False vocal cords: Folds of mucous membrane, not involved in sound production.
        • Rima glottidis: Narrow opening between vocal cords.
        • Laryngeal prominence (Adam's apple): Mid-ventral part of thyroid cartilage.
      • Trachea (Windpipe): Straight tube extending to the mid-thoracic cavity.
        • C-shaped hyaline cartilage rings: Support the trachea, keeping it open.
        • Pseudostratified ciliated epithelium: Lines the trachea internally.
      • Bronchi and Bronchioles:
        • Primary bronchi: Trachea divides into right and left primary bronchi at the level of the fifth thoracic vertebra.
        • Secondary bronchi: Branching of primary bronchi within the lungs.
        • Tertiary bronchi: Further branching of secondary bronchi.
        • Bronchioles: Repeated divisions of bronchi forming primary, secondary, tertiary, terminal, and respiratory bronchioles.
        • Alveolar ducts: Respiratory bronchioles terminate into alveolar ducts.
        • Alveolar sacs: Alveolar ducts end in alveolar sacs.
        • Incomplete cartilaginous rings: Support bronchi and initial bronchioles.
        • Pulmonary tree: Branching network of trachea, bronchi, and bronchioles, resembling an upside-down tree.
      • Lungs: Fill the majority of the thoracic cavity.
        • Pleura: Double-layered membrane surrounding the lungs, with pleural fluid between them to reduce friction.
        • Conducting part: External nostrils to terminal bronchioles, transporting air, clearing particles, humidifying, and warming air.
        • Respiratory (exchange part): Alveoli and their ducts, where O2 and CO2 exchange occurs.
      • Thoracic chamber: Anatomically airtight chamber containing the lungs.
        • Dorsal: Vertebral column.
        • Ventral: Sternum.
        • Lateral: Ribs.
        • Lower: Dome-shaped diaphragm.
        • Pulmonary volume: Changes in thoracic chamber volume affect lung volume, essential for breathing.

    Steps Involved in Human Respiration

    • Breathing or Pulmonary Ventilation: Drawing in atmospheric air (21% O2) and expelling alveolar air (rich in CO2).
    • Diffusion of Gases Across the Alveolar Membrane: Exchange of O2 and CO2 between the alveoli and blood.
    • Transport of Gases by Blood: Moving gases between lungs and tissues.
    • Diffusion of O2 and CO2 Between Blood and Tissues: Gas exchange between blood in systemic capillaries and tissues.
    • Utilization of O2 by Cells and CO2 Production: Cellular respiration - cells use O2 for catabolic reactions, producing CO2, H2O, and ATP.

    Mechanism of Breathing

    • Breathing: Process of maximizing gas exchange by creating a pressure gradient between lungs and atmosphere.
    • Inspiration: Active process involving muscle contraction.
      • Diaphragm: Contraction increases thoracic chamber volume in the anteroposterior axis.
      • External intercostal muscles: Contraction lifts ribs and sternum, increasing thoracic volume in the dorso-ventral axis.
      • Increased thoracic volume: Leads to an increase in pulmonary volume, decreasing intra-pulmonary pressure below atmospheric pressure, forcing air into the lungs.
    • Expiration: Passive process involving muscle relaxation.
      • Diaphragm and external intercostal muscles: Relaxation returns diaphragm and sternum to their normal positions, decreasing thoracic and pulmonary volume.
      • Increased intra-pulmonary pressure: Exceeds atmospheric pressure, forcing air out of the lungs.
    • Forced expiration: Contraction of internal intercostal muscles and lateral abdominal muscles.
    • Average breathing rate: 12-16 breaths per minute.
    • Spirometer: Used to measure air volume involved in breathing movements, aiding in the assessment of pulmonary function.

    Gas Exchange

    • Alveoli: Primary sites of gas exchange in the lungs.
    • Simple Diffusion: The exchange of gases is based on simple diffusion, influenced by:
      • Partial pressure/concentration gradient: Difference in gas pressures between alveoli and blood, and between blood and tissues.
      • Solubility of gases: CO2 is more soluble than O2, facilitating its diffusion.
      • Thickness of the respiratory membrane: Thin membrane favors diffusion.
      • Surface area: Larger surface area maximizes diffusion.
      • Distance of diffusion: Short diffusion distance is beneficial.
    • Partial Pressure: Individual gas pressure in a mixture.
      • pO2: Partial pressure of oxygen.
      • pCO2: Partial pressure of carbon dioxide.
    • Gas exchange gradients:
      • Alveoli to blood: High pO2 in alveoli drives O2 diffusion into blood.
      • Blood to tissues: High pO2 in blood drives O2 diffusion into tissues.
      • Tissues to blood: High pCO2 in tissues drives CO2 diffusion into blood.
      • Blood to alveoli: High pCO2 in blood drives CO2 diffusion into alveoli.

    Transport of Gases

    • Blood: Medium for transporting O2 and CO2.
    • Transport of Oxygen:
      • Plasma: Carries about 3% of O2 in dissolved form.
      • Red blood cells (RBCs): Carry about 97% of O2.
        • Hemoglobin (Hb): Oxygen-carrying pigment in RBCs.
          • Oxyhemoglobin: Hb bound to oxygen, bright red in color.
          • Oxygenation of hemoglobin: Hb + 4O2 → Hb(O2)4
          • Factors affecting oxygen binding:
            • Partial pressure of O2: Higher pO2 at lungs promotes oxygen binding.
            • Partial pressure of CO2: Higher pCO2 reduces oxygen affinity.
            • Hydrogen ion concentration (pH): Lower pH (higher acidity) reduces oxygen affinity.
            • Temperature: Higher temperature reduces oxygen affinity.
      • Oxygen-Hemoglobin Dissociation Curve: A sigmoid curve showing the relationship between hemoglobin saturation and pO2.
        • Shift to the right: Conditions like high pCO2, low pH, and high temperature decrease oxygen affinity and shift the curve to the right.
        • Bohr Effect: The effect of pCO2 and H+ concentration on oxygen affinity of hemoglobin.
    • Transport of Carbon Dioxide:
      • Dissolved state: 7% of CO2 is carried dissolved in plasma.
      • Carbamino compounds: 20-25% of CO2 combines with hemoglobin to form carbaminohemoglobin.
      • Bicarbonates: About 70% of CO2 is transported as bicarbonate.
        • Carbonic anhydrase: Enzyme in RBCs and plasma that facilitates the conversion of CO2 to carbonic acid.
        • Hemoglobin: Amphoteric compound, can bind oxygen and release CO2 in oxygen-rich areas, and bind CO2 and release oxygen in CO2-rich areas.

    Carbon Dioxide Transport

    • Carbon dioxide is transported in the blood as bicarbonate, dissolved in plasma, and bound to haemoglobin.
    • At the tissues, high partial pressure of CO2 leads to formation of carbonic acid, which dissociates to bicarbonate and hydrogen ions.
    • Bicarbonate diffuses out of red blood cells into the plasma, while hydrogen ions are buffered by haemoglobin.
    • This process, known as the chloride shift, involves the exchange of chloride and bicarbonate ions between the red blood cells and plasma to maintain electrolyte balance.
    • At the lungs, low partial pressure of CO2 reverses this process.

    Regulation of Respiratory Movements

    • The respiratory rhythm centre in the medulla controls breathing.
    • The pneumotaxic centre in the pons can modify the duration of inspiration and respiratory rate.
    • Chemosensitive areas in the medulla are sensitive to changes in CO2 and hydrogen ion concentrations and stimulate the respiratory rhythm centre to adjust breathing.
    • Receptors in the aortic arch and carotid artery detect changes in CO2 and H+ levels and send signals to the respiratory rhythm centre and pneumotaxic centre.

    Respiratory Volumes and Capacities

    • Tidal Volume (TV): The amount of air inhaled or exhaled during normal breathing (approximately 500 ml).
    • Inspiratory Reserve Volume (IRV): The additional volume of air that can be inhaled during forced inspiration (about 2500-3000 ml).
    • Expiratory Reserve Volume (ERV): The additional volume of air that can be exhaled during forced expiration (about 1000-1100 ml).
    • Residual Volume (RV): The volume of air remaining in the lungs after forceful expiration (about 1100-1200 ml).
    • Inspiratory Capacity (IC): The total volume of air that can be inhaled after normal expiration (IC = TV + IRV, about 3000-3500 ml).
    • Functional Residual Capacity (FRC): The volume of air remaining in the lungs after normal expiration (FRC = ERV + RV).
    • Vital Capacity (VC): The maximum volume of air that can be exhaled after a forced inspiration (VC = TV + IRV + ERV).
    • Total Lung Capacity (TLC): The total volume of air that can be accommodated in the lungs at the end of a forced inspiration (TLC = VC + RV or TLC = ERV + IRV + TV + RV).

    Disorders of the Respiratory System

    • Asthma: Difficulty breathing due to inflammation of bronchi and bronchioles, characterized by spasms of smooth muscles in the airway walls. Symptoms include coughing, wheezing, and shortness of breath.
    • Emphysema: Chronic disorder where alveolar walls are damaged and respiratory surface area is decreased. Caused by smoking and characterized by fewer, larger alveoli and a more fibrous, less elastic lung.
    • Bronchitis: Inflammation of bronchi, leading to swelling of the mucus lining, increased mucus production, and narrowing of airways. Symptoms include chronic cough with thick mucus.
    • Pneumonia: Infection of the lungs caused by bacteria, viruses, fungi, protozoans, and mycoplasmas. Symptoms include inflammation of the lungs, accumulation of mucus in alveoli, and impaired gas exchange.
    • Emphysema, chronic bronchitis, and asthma fall under Chronic Obstructive Pulmonary Diseases (COPDs).
    • Occupational Respiratory Disorders: Caused by exposure to harmful substances in various industries, leading to inflammation of the airways and lungs.
      • Asbestosis: Chronic exposure to asbestos dust.
      • Silicosis: Long-term exposure to silica dust in mining industries.
      • Siderosis: Deposition of inhaled iron particles in tissues can cause pneumoconiosis, hyperferremia, and hemosiderosis.
      • Black-lung disease: Developed from inhalation of coal dust, common in coal miners.

    Respiration and Energy

    • Respiration is a catabolic process that releases energy through the oxidation of food.
    • Oxygen is used in the production of metabolic water, a byproduct of calorie burning.
    • Gills use a countercurrent flow mechanism to efficiently oxygenate blood.
    • Birds have air sacs and parabronchi that allow for continuous gas exchange during both inhalation and exhalation.
    • Tracheate animals, like insects, have tracheae and tracheoles that deliver oxygen directly to each cell, making them very active.
    • Mountain sickness occurs at high altitudes due to decreased oxygen levels (pO2).
    • The ribcage and diaphragm help mammals breathe more effectively.
    • The respiratory center controls oxygen and carbon dioxide homeostasis.
    • The medulla oblongata regulates inhalation and exhalation.
    • A pneumotaxic center in the pons controls the rate and depth of breathing.
    • Humans cannot hold their breath for long due to the body's need for oxygen.
    • Marine mammals, like elephant seals, have myoglobin (muscle hemoglobin) with a higher affinity for oxygen, allowing them to stay underwater for extended periods.
    • Cells require a constant supply of energy produced by the oxidation of glucose, amino acids, and fatty acids, transported through the circulatory system.

    Types of Respiration

    • Anaerobic respiration: incomplete breakdown of organic molecules with less energy yield, occurring in the absence of oxygen.
      • Examples: yeast, bacteria, and muscles under certain conditions.
      • C6H12O6 → 2CO2+ 2C2H5OH(ethanol)+2ATP
      • C6H12O6 → 2C3H6O3(lactic acid)+2ATP
    • Aerobic respiration: complete breakdown of organic molecules with more energy yield, requiring oxygen.
      • C6H12O6+6H2O+6O2 → 6CO2+12H2O+36ATP

    Respiratory Organs in Animals

    • Protozoans and lower invertebrates have simple diffusion across their body surface for gas exchange.
    • Earthworms use their moist body wall for gas exchange.
    • Insects use a network of tubes (tracheal system) to transport air.
    • Spiders and scorpions have "book lungs" for aerial respiration.
    • Aquatic arthropods and mollusks use gills for gas exchange.
    • Terrestrial forms use lungs, including reptiles, birds, and mammals.
    • Amphibians use both moist skin and lungs for gas exchange.

    Human Respiratory System

    • External Nostrils: Openings that lead into the nasal chambers.

    • Nasal Chambers: Cavities above the palate separated by a nasal septum, with three parts: (1) vestibular part (hair and glands to filter dust), (2) respiratory part (conditioning inhaled air, containing turbinals), and (3) olfactory part (detecting smell).

    • Naso-pharynx: Upper portion of the pharynx connected to the nasal chambers via internal nostrils.

    • Larynx: Cartilaginous box for sound production (voice box) containing nine cartilages.

      • Thyroid: Unpaired cartilage that forms the Adam's apple, larger in males.
      • Cricoid: Unpaired cartilage.
      • Epiglottis: Unpaired, leaf-like flap that prevents food from entering the larynx.
      • Corniculate: Paired, small cartilages.
      • Arytenoid: Paired cartilages that anchor the vocal cords.
      • Cuneiform: Paired cartilages.
      • Vocal Cords: Yellow elastic fibres connecting the thyroid and arytenoid cartilages, producing sound.
      • True vocal cords: produce sound
      • False vocal cords: folds of mucous membrane that do not produce sound.
      • Rima Glottidis: Opening between the true vocal cords and the arytenoid cartilages.

    • Trachea: Windpipe, supported by "C" shaped hyaline cartilage rings.

    • Bronchi: Trachea branches into two primary bronchi, each entering a lung and further dividing into secondary and tertiary bronchi.

    • Bronchioles: Tertiary bronchi further divide into smaller bronchioles.

      • Bronchi and initial bronchioles are supported by incomplete cartilaginous rings.

    • Alveoli: Tiny air sacs at the ends of bronchioles, the primary sites of gas exchange.

    • Lungs: Paired organs located in the thoracic cavity, surrounded by a double-layered pleura with pleural fluid for lubrication.

      • Conducting part: External nostrils to terminal bronchioles, transports air, cleanses it, humidifies it and warms it.
      • Respiratory part: Alveoli, where gas exchange takes place.

    • Thoracic Cavity: Anatomically airtight chamber formed by the vertebral column, sternum, ribs, and diaphragm.

    Mechanism of Breathing

    • Breathing (Pulmonary Ventilation): Movement of air into and out of the lungs, creating a pressure gradient.
      • Inspiration: Drawing air into the lungs, active process requiring muscle contraction.
        • Diaphragm contraction increases thoracic volume in the anteroposterior axis.
        • External intercostal muscle contraction lifts ribs and sternum, increasing thoracic volume in the dorso-ventral axis.
        • Overall thoracic volume increase leads to pulmonary volume increase, decreasing intra-pulmonary pressure and drawing air into the lungs.
      • Expiration: Release of alveolar air, passive process due to muscle relaxation.
        • Diaphragm and external intercostal muscles relax, reducing thoracic and pulmonary volume.
        • Intra-pulmonary pressure increases, forcing air out of the lungs.
        • Forced expiration: Internal intercostal muscles and lateral abdominal muscles contract to increase the force of expiration.
    • Spirometer: A device used to measure the volume of air involved in breathing movements, assessing pulmonary function.

    Gas Exchange

    • Alveoli: Primary sites of gas exchange in the lungs, along with blood and tissues.
    • Simple Diffusion: Gas exchange occurs through simple diffusion based on partial pressure gradients, solubility of gases, thickness of the respiratory membrane, surface area, and distance of diffusion.
    • Partial Pressure: Pressure contributed by an individual gas in a mixture.
      • pO2: Partial pressure of oxygen.
      • pCO2: Partial pressure of carbon dioxide.

    Partial Pressure of O2 and CO2 at Different Locations:

    Location pO2 (mmHg) pCO2 (mmHg)
    Atmospheric Air 159 0.3
    Alveoli 104 40
    Deoxygenated Blood 40 45
    Oxygenated Blood 95 40
    Tissues 40 45
    • Solubility: CO2 is more soluble than O2, meaning it can diffuse faster across the respiratory membrane.
    • Respiratory Membrane: Includes the squamous epithelium of the alveolar wall, endothelium of the alveolar capillaries, and basement material.
      • Thin membrane facilitates fast diffusion.

    Gas Exchange in the Body:

    • Pulmonary Gas Exchange (External Respiration):
      • O2 diffuses from alveolar air into the blood in the pulmonary capillaries.
      • CO2 diffuses from blood into the alveolar air.
    • Systemic Gas Exchange (Internal Respiration):
      • O2 diffuses from the blood in systemic capillaries into tissues.
      • CO2 diffuses from tissues into the systemic capillaries.

    Transport of Gases

    • Blood: Medium used to transport O2 and CO2.

    Oxygen Transport:

    • Plasma: 3% of O2 transported dissolved in plasma.

    • Red Blood Cells (RBCs): 97% of O2 transported by RBCs using haemoglobin.

      • Haemoglobin: Red pigmented protein containing iron, each molecule can bind up to four oxygen molecules.
        • Oxygenation: Binding of oxygen to haemoglobin in the lungs, forming oxyhaemoglobin, which is bright red. Hb + 4O2 → Hb(O2)4
        • Deoxygenation: Dissociation of oxygen from oxyhaemoglobin in tissues, resulting in haemoglobin and oxygen.

    • Factors Affecting Oxygen Binding:

      • Partial Pressure of O2: Higher pO2 in the lungs promotes binding of oxygen to haemoglobin, while lower pO2 in tissues promotes dissociation.
      • Partial Pressure of CO2: Higher pCO2 decreases the affinity of haemoglobin for oxygen.
      • Hydrogen Ion Concentration (pH): Higher H+ concentration (lower pH) decreases the affinity of haemoglobin for oxygen.
      • Temperature: Higher temperature decreases the affinity of haemoglobin for oxygen.

    • Oxyhaemoglobin Dissociation Curve: A sigmoid curve showing the relationship between haemoglobin saturation with oxygen and partial pressure of oxygen.

      • Shift to the right: Indicates decreased affinity of haemoglobin for oxygen, caused by high pCO2, low pH, or higher temperature.
      • Shift to the left: Higher affinity of haemoglobin for oxygen, caused by low pCO2, high pH, or low temperature.

    • Bohr Effect: The effect of pCO2 and H+ concentration on the oxygen affinity of haemoglobin.

      • High CO2 and low pH: decrease the affinity of haemoglobin for oxygen.
      • Low CO2 and high pH: increase the affinity of haemoglobin for oxygen.

    Carbon Dioxide Transport:

    • Dissolved State: 7% of CO2 transported dissolved in plasma.

    • Carbaminohaemoglobin: 20-25% of CO2 binds to amino groups in haemoglobin, forming carbaminohaemoglobin. Hb-NH2 + CO2 → Hb-NHCOO- + H+.

      • Binding depends on pCO2: High pCO2 in tissues promotes binding, while low pCO2 in alveoli promotes dissociation.

    • Bicarbonates: 70% of CO2 transported as bicarbonate.

      • Carbonic Anhydrase: Enzyme present in RBCs that catalyses the reversible reaction between CO2 and H2O to form carbonic acid (H2CO3).
      • Bicarbonate Formation: Carbonic acid dissociates into bicarbonate (HCO3-) and H+.
      • Bicarbonate Movement: HCO3- diffuses out of RBCs into plasma, while H+ binds to haemoglobin to maintain PH balance.
      • Bicarbonate Transport: Bicarbonate ions are transported to the lungs.
      • Reverse Reaction: In lungs, low pCO2 promotes the conversion of bicarbonate back into CO2, which is exhaled.

    • Deoxygenated (Venous) Blood: Has a slightly lower pH than oxygenated (arterial) blood due to the presence of CO2.

    • **Hb: ** Amphoteric compound, meaning it can act as both an acid and a base.

    Carbon Dioxide Transport

    • CO2 is transported in the blood in three ways: dissolved in plasma, bound to hemoglobin, and as bicarbonate ions.
    • Bicarbonate ions are the most abundant form of transported CO2.
    • At tissues, CO2 diffuses into the blood and reacts with water to form carbonic acid (H2CO3), which then dissociates into bicarbonate ions (HCO3-) and hydrogen ions (H+).
    • Hemoglobin buffers the H+ ions, preventing a decrease in blood pH.
    • At the lungs, the reaction reverses, releasing CO2 for exhalation.

    Chloride Shift

    • Bicarbonate ions diffuse from the RBC into the plasma at the tissues.
    • Chloride ions diffuse from the plasma into the RBC to maintain electrical neutrality – this is the chloride shift.
    • The chloride shift helps facilitate CO2 transport and maintains blood pH.

    Regulation of Respiratory Movements

    • The respiratory rhythm center in the medulla oblongata controls the basic rhythm of breathing.
    • The pneumotaxic center in the pons moderates the rhythm of breathing.
    • Chemoreceptors in the medulla oblongata and aortic arch and carotid arteries detect changes in blood CO2 and H+ levels.
    • Oxygen plays a relatively insignificant role in regulating breathing.

    Respiratory Volumes and Capacities

    • Tidal volume (TV): The volume of air inhaled or exhaled during normal breathing (approximately 500 mL).
    • Inspiratory reserve volume (IRV): The additional volume of air that can be inhaled forcefully after a normal inhalation (about 2500-3000 mL).
    • Expiratory reserve volume (ERV): The additional volume of air that can be exhaled forcefully after a normal exhalation (about 1000-1100 mL).
    • Residual volume (RV): The volume of air remaining in the lungs after forced expiration (about 1100-1200 mL).
    • Inspiratory capacity (IC): The total volume of air that can be inhaled after a normal exhalation; IC = TV + IRV (around 3000-3500 mL).
    • Functional residual capacity (FRC): The volume of air remaining in the lungs after a normal exhalation; FRC = ERV + RV.
    • Vital capacity (VC): The maximum volume of air that can be exhaled after a forced inhalation; VC = TV + IRV + ERV.
    • Total lung capacity (TLC): The total volume of air that the lungs can hold; TLC = VC + RV, or TLC = ERV + IRV + TV + RV.

    Disorders of the Respiratory System

    • Asthma: Inflammation of the bronchi and bronchioles, causing spasms of smooth muscle in the airway walls. Symptoms include coughing, wheezing, and difficulty breathing.
    • Emphysema: Chronic disorder characterized by damage to and coalescence of alveolar walls, reducing respiratory surface area. Lung shows larger but fewer alveoli, with increased fibrosis and decreased elasticity.
    • Bronchitis: Inflammation of the bronchi, causing swelling of the mucous lining, increased mucus production, and narrowing of the bronchi. Symptoms include chronic cough with thick mucus or phlegm.
    • Pneumonia: Infection of the lungs caused by bacteria, viruses, fungi, protozoa, or mycoplasmas. Symptoms include inflammation of the lungs, accumulation of mucus in alveoli, and impaired gas exchange.
    • Chronic obstructive pulmonary disease (COPD): A group of progressive lung diseases that cause airflow obstruction; includes emphysema, chronic bronchitis, and asthma.
    • Occupational respiratory disorders: Lung diseases caused by exposure to harmful substances in the workplace, including:
      • Asbestosis: Caused by chronic exposure to asbestos dust.
      • Silicosis: Caused by long-term exposure to silica dust.
      • Siderosis: Caused by deposition of inhaled iron particles in tissues.
      • Black-lung disease (coal workers' pneumoconiosis): Caused by inhalation of coal dust.

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    Test your knowledge on the mechanisms of respiration across different species, including gills, lungs, and tracheae. This quiz explores how oxygen is carried and utilized in various environments, as well as the brain's role in regulating breathing. Perfect for biology enthusiasts or students studying physiology.

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