Physiology of Ventilation and Gas Exchange
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Questions and Answers

What determines which capillaries remain open and which close off in the lungs?

  • Blood pressure (correct)
  • Gravity
  • Oxygen saturation
  • Alveolar ventilation

    • What is the primary function of haemoglobin in the context of gas exchange?

  • To buffer excess hydrogen ions
  • To regulate alveolar ventilation
  • To transport oxygen in the blood (correct)
  • To facilitate the diffusion of gases across cell membranes

    • What is a consequence of a mismatch between ventilation and perfusion?

  • Increased gas exchange efficiency
  • Improved oxygen binding affinity of haemoglobin
  • Impaired gas exchange between the atmosphere and arterial blood (correct)
  • Enhanced carbon dioxide transport

    • Which of the following factors influences the oxygen binding affinity of haemoglobin?

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

    What is the primary mechanism of carbon dioxide transport in the blood?

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

    What is the role of bicarbonate in the context of gas exchange?

    <p>To buffer excess hydrogen ions</p> Signup and view all the answers

    What is the primary factor affecting gas exchange in healthy people?

    <p>Concentration gradient between alveoli and blood</p> Signup and view all the answers

    What is the effect of a decrease in the amount of alveolar surface area available for gas exchange?

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

    Why is haemoglobin necessary for oxygen transport in the blood?

    <p>Because oxygen is not very soluble in plasma</p> Signup and view all the answers

    What is an example of the reserve capacity of the body?

    <p>The ability to recruit additional capillary beds during exercise</p> Signup and view all the answers

    What is the percentage of oxygen in the blood that is dissolved in the plasma?

    <p>Less than 2%</p> Signup and view all the answers

    What is the response of the arterioles when ventilation of alveoli in one area of the lung is diminished?

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

    How does an increase in the diffusion distance between the alveolar air space and the blood affect gas exchange?

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

    What is the result of significantly impaired diffusion of gases between the alveoli and blood or inadequate oxygen transport in the blood?

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

    What is the relative solubility of carbon dioxide compared to oxygen?

    <p>Carbon dioxide is 20x more soluble than oxygen</p> Signup and view all the answers

    What do the sensors in the body monitor to avoid hypoxia and hypercapnia?

    <p>Arterial blood composition</p> Signup and view all the answers

    What is the term for lower-than-normal volumes of fresh air entering the alveoli?

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

    What is the time it takes for diffusion to reach equilibrium in the lungs?

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

    What percentage of oxygen in our body is transported by haemoglobin?

    <p>More than 98%</p> Signup and view all the answers

    What is the term for haemoglobin bound to oxygen?

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

    What is the effect of a decrease in cellular PO2 on haemoglobin?

    <p>Hb releases additional O2</p> Signup and view all the answers

    What is the term for the shift in the Hb saturation curve due to a change in pH?

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

    What is the name of the molecule that affects O2-Hb binding?

    <p>2,3-Bisphosphoglycerate</p> Signup and view all the answers

    If half the available binding sites on haemoglobin molecules are occupied by O2 molecules, what is the oxygen saturation of the blood?

    <p>50%</p> Signup and view all the answers

    What is the effect of increased 2,3-BPG production on haemoglobin?

    <p>It lowers the binding affinity of Hb and shifts the HbO2 saturation curve to the right.</p> Signup and view all the answers

    What is unique about foetal haemoglobin compared to adult haemoglobin?

    <p>It has two gamma protein chains instead of beta chains.</p> Signup and view all the answers

    What is the role of haemoglobin in buffering H+ ions?

    <p>It prevents large changes in the body’s pH by buffering H+ ions.</p> Signup and view all the answers

    What occurs when blood PCO2 is elevated?

    <p>Haemoglobin cannot soak up all the H+ ions and excess H+ accumulate in the plasma.</p> Signup and view all the answers

    What is the consequence of excess H+ accumulation in the plasma?

    <p>Respiratory acidosis.</p> Signup and view all the answers

    What happens to carbon dioxide at the lungs?

    <p>It is removed from the blood.</p> Signup and view all the answers

    What is the primary mechanism by which the body attempts to match air flow and blood flow in the lungs?

    <p>Regulating the diameters of the arterioles and bronchioles</p> Signup and view all the answers

    What is the result of significantly impaired diffusion of gases between the alveoli and blood or inadequate oxygen transport in the blood?

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

    What determines the efficiency of alveolar gas exchange?

    <p>Many variables including the composition of the inspired air, low alveolar ventilation, and diffusion problems</p> Signup and view all the answers

    What is the response of the arterioles to a decrease in PO2 in one area of the lung?

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

    What is the time it takes for diffusion to reach equilibrium in the lungs?

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

    What is the term for the condition characterised by lower-than-normal volumes of fresh air entering the alveoli?

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

    What is the primary benefit of having collapsible capillaries in the lungs?

    <p>Matching of ventilation and perfusion</p> Signup and view all the answers

    Which of the following is a consequence of a mismatch between ventilation and perfusion at the local level?

    <p>Decreased carbon dioxide removal from the cells</p> Signup and view all the answers

    What is the primary mechanism by which gas solubility affects diffusion and gas exchange?

    <p>Increased partial pressure gradient of gases</p> Signup and view all the answers

    What is the primary difference between foetal and adult haemoglobin in terms of oxygen transport?

    <p>Foetal haemoglobin has a higher affinity for oxygen</p> Signup and view all the answers

    What is the physiological significance of the oxygen saturation curve in terms of haemoglobin function?

    <p>It shows the effect of pH on haemoglobin binding affinity</p> Signup and view all the answers

    What is the primary function of bicarbonate in the context of carbon dioxide transport in the blood?

    <p>Buffering of excess H+ ions</p> Signup and view all the answers

    What is the primary reason why oxygen requires oxygen-carrying molecules to transport it in the blood?

    <p>Oxygen has low solubility in the blood</p> Signup and view all the answers

    What is the effect of an increase in the thickness of the alveolar-capillary exchange barrier on gas exchange?

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

    What is the percentage of oxygen in the blood that is bound to haemoglobin?

    <p>More than 90%</p> Signup and view all the answers

    How does the solubility of carbon dioxide compare to oxygen?

    <p>Carbon dioxide is 20 times more soluble than oxygen</p> Signup and view all the answers

    What are the two components of oxygen transport in the blood?

    <p>Dissolved oxygen and oxygen bound to haemoglobin</p> Signup and view all the answers

    What is the effect of an increase in the diffusion distance between the alveolar air space and the blood on oxygen transport?

    <p>Oxygen transport is slower</p> Signup and view all the answers

    What is the primary effect of increased 2,3-BPG production on the oxygen binding affinity of haemoglobin?

    <p>Decreases the binding affinity of Hb</p> Signup and view all the answers

    What is the unique characteristic of foetal haemoglobin compared to adult haemoglobin?

    <p>It has two gamma protein chains instead of the two beta chains</p> Signup and view all the answers

    What is the role of haemoglobin in maintaining the body's pH balance?

    <p>It buffers H+ ions</p> Signup and view all the answers

    What occurs when the body's PCO2 is elevated?

    <p>Haemoglobin cannot absorb all the H+ ions and excess H+ accumulate in the plasma</p> Signup and view all the answers

    What is the consequence of excess H+ accumulation in the plasma?

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

    What is the primary function of bicarbonate in the body?

    <p>The most important extracellular buffer</p> Signup and view all the answers

    What is the approximate percentage of oxygen in our body that is transported by haemoglobin?

    <p>98%</p> Signup and view all the answers

    What is the maximum number of oxygen molecules that one haemoglobin molecule can bind?

    <p>4</p> Signup and view all the answers

    What is the term for the blood when all binding sites on all haemoglobin molecules are occupied by oxygen molecules?

    <p>100% oxygenated</p> Signup and view all the answers

    What is the term for the shift in the haemoglobin saturation curve that results from a change in pH?

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

    What is the effect of a decrease in cellular PO2 on haemoglobin?

    <p>Haemoglobin releases additional O2</p> Signup and view all the answers

    What is the name of the molecule that affects O2-Hb binding?

    <p>2,3-BPG</p> Signup and view all the answers

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