Ventilation Regulation: Carotid Body Cells
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Questions and Answers

What is the primary stimulus for increasing ventilation in the carotid and aortic glomus cells?

  • Arterial PO2 below 60 mmHg
  • Increased PCO2
  • Decreased plasma pH
  • All of the above (correct)

    • What is the mechanism by which Ca2+ enters the receptor cell in the carotid body?

  • Through voltage-gated K+ channels
  • Through voltage-gated Ca2+ channels (correct)
  • Through mechanically gated Ca2+ channels
  • Through ligand-gated Ca2+ channels

    • What is the primary response of the central chemoreceptors to an increase in arterial PCO2?

  • Increased ventilation (correct)
  • No change in ventilation
  • Decreased ventilation
  • bronchoconstriction

    • What is the primary function of the protective reflexes of the respiratory tract?

    <p>To respond to physical injury or irritation</p> Signup and view all the answers

    What is the role of parasympathetic neurons in the respiratory tract?

    <p>To mediate bronchoconstriction</p> Signup and view all the answers

    What is the threshold for stimulation of ventilation by low oxygen levels?

    <p>Arterial PO2 below 60 mmHg</p> Signup and view all the answers

    What is the partial pressure of carbon dioxide above which is considered hypercapnia?

    <p>45 mmHg</p> Signup and view all the answers

    What is the approximate partial pressure of oxygen in arterial blood at sea level?

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

    Which of the following factors that influence diffusion of respiratory gases is the most variable and important factor to consider?

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

    What is the process by which dissolved gases are exchanged between the blood and interstitial fluids?

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

    Which of the following lung pathologies is most likely to result from certain kinds of heart disease?

    <p>Pulmonary oedema</p> Signup and view all the answers

    What is the approximate atmospheric pressure at sea level?

    <p>760 mmHg</p> Signup and view all the answers

    What is the primary factor influencing airway resistance?

    <p>The diameter of the airway</p> Signup and view all the answers

    In which condition is fluid accumulation in interstitial spaces most likely to occur?

    <p>Pulmonary oedema</p> Signup and view all the answers

    What happens to the diffusion distance in the alveoli-capillary interface in fibrotic lung disease?

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

    What is the effect of increased temperature, PCO2, and 2,3-BPG on the affinity of haemoglobin for oxygen?

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

    What is the role of carbonic anhydrase in red blood cells?

    <p>To convert CO2 into bicarbonate ions</p> Signup and view all the answers

    What is the immediate product of carbonic acid dissociation?

    <p>Bicarbonate anion and a proton</p> Signup and view all the answers

    What is the primary mechanism by which the diaphragm generates a negative alveolar pressure during inspiration?

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

    Which nervous system stimulates the contractility of airway smooth muscle during exercise?

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

    What is the primary effect of lung surfactant on alveoli?

    <p>It reduces the surface tension at the air-fluid interface</p> Signup and view all the answers

    What is the primary consequence of lacking lung surfactant?

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

    What is the primary effect of stimulating lung stretch receptors?

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

    What is the primary purpose of maintaining airways in a fully open state during breathing?

    <p>To maximize airflow and minimize the effort of breathing</p> Signup and view all the answers

    What stimulus would most likely trigger an increase in ventilation in a healthy individual?

    <p>Reduced arterial PO2, sensed by central chemoreceptors</p> Signup and view all the answers

    Which nerves carry afferent signals from peripheral chemoreceptors to the integrating center?

    <p>Vagus and glossopharyngeal nerves</p> Signup and view all the answers

    What is the term for the space between the parietal and visceral pleura?

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

    During inspiration, what happens to intrapleural pressure?

    <p>It becomes more negative</p> Signup and view all the answers

    What is the primary function of the vagus nerve in the control of breathing?

    <p>Carrying afferent signals from lung stretch and irritant receptors</p> Signup and view all the answers

    Which of the following statements about the control of breathing is true?

    <p>The glossopharyngeal nerve carries afferent signals from the carotid sinus</p> Signup and view all the answers

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

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

    What happens to the oxygen-haemoglobin curve when there is an increase in tissue PCO2?

    <p>It shifts right</p> Signup and view all the answers

    What is the characteristic of haemoglobin that makes it a good match for its function as an oxygen carrier?

    <p>It can bind four oxygen molecules</p> Signup and view all the answers

    What is the percentage saturation of haemoglobin with oxygen at a PO2 of 70 mmHg and normal temperature and pH?

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

    How is most of the oxygen transported by the blood?

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

    What is the primary carrier of oxygen in humans?

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

    What is the mechanism by which the central chemoreceptors respond to changes in PCO2?

    <p>By responding to changes in pH within the cerebrospinal fluid</p> Signup and view all the answers

    What is the effect of a decrease in plasma pH on ventilation?

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

    What is the primary neurotransmitter involved in the signal transmission from the carotid body to the brainstem respiratory networks?

    <p>Unspecified neurotransmitter</p> Signup and view all the answers

    What is the response of the central chemoreceptors to an increase in CO2 in the cerebrospinal fluid?

    <p>They increase ventilation</p> Signup and view all the answers

    What is the primary mechanism by which the carotid body cells respond to changes in PO2?

    <p>By directly sensing changes in PO2</p> Signup and view all the answers

    What is the primary function of the bronchoconstriction reflex in the respiratory tract?

    <p>To respond to physical injury or irritation of the respiratory tract</p> Signup and view all the answers

    What is the primary effect of increased carbon dioxide levels on the haemoglobin dissociation curve?

    <p>A rightward shift of the curve, decreasing haemoglobin's affinity for oxygen</p> Signup and view all the answers

    Which of the following methods is responsible for transporting most of the carbon dioxide in the blood?

    <p>Bicarbonate ions</p> Signup and view all the answers

    What is the primary function of the nucleus tractus solitarius (NTS) in the medulla oblongata?

    <p>Receiving inputs from fibres carrying sensory information</p> Signup and view all the answers

    What is the most important chemical regulator of respiration?

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

    An increase in the level of carbon dioxide in the blood would most likely result in which of the following?

    <p>An increase in the rate of breathing</p> Signup and view all the answers

    What is the effect of carbon dioxide on the binding capacity of haemoglobin?

    <p>It decreases the binding capacity of haemoglobin</p> Signup and view all the answers

    What would be the direct effect of an inhibitor of carbonic anhydrase on the blood pH?

    <p>Increase blood pH due to decreased conversion to protons</p> Signup and view all the answers

    When would the chloride shift occur in red blood cells?

    <p>When hydrogen ions leave the red blood cells</p> Signup and view all the answers

    What is the name of the effect that causes a shift in the oxygen dissociation curve to the right?

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

    Which structure pulls down during inspiration to generate a negative alveolar pressure and recoils back up during expiration to reverse that pressure change?

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

    What is the effect of an inhibitor of carbonic anhydrase on the formation of bicarbonate in the blood?

    <p>Decrease the formation of bicarbonate</p> Signup and view all the answers

    What is the effect of the Bohr effect on the oxygen binding capacity of haemoglobin?

    <p>Decrease the oxygen binding capacity of haemoglobin</p> Signup and view all the answers

    What is the primary mechanism by which the diaphragm generates a negative alveolar pressure during inspiration?

    <p>It pulls down to increase the thoracic volume.</p> Signup and view all the answers

    Which statement best describes the control of airway resistance?

    <p>It is important to maintain airways in a fully open state during breathing to maximise airflow and minimise the effort of breathing.</p> Signup and view all the answers

    What is the primary effect of lung surfactant on alveoli?

    <p>It reduces the surface tension at the air-fluid interface of alveoli, thus preventing alveolar collapse.</p> Signup and view all the answers

    What is sensed to cause the change in ventilation during exercise?

    <p>Increase in arterial carbon dioxide levels.</p> Signup and view all the answers

    What happens to the diaphragm during expiration?

    <p>It recoils back up to decrease the thoracic volume.</p> Signup and view all the answers

    What is the primary consequence of lacking lung surfactant?

    <p>Alveolar collapse.</p> Signup and view all the answers

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