Sheet 9 Physiology
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Questions and Answers

What is the main purpose of controlling breathing?

  • To regulate the body's temperature
  • To increase PaCO2 levels
  • To decrease PaO2 levels
  • To maintain normal ABGs (Homeostasis of O2, CO2, H+) (correct)

    • Which factor does not affect the controller or feedback systems of breathing?

  • H+ levels
  • PaCO2 levels
  • PH levels
  • PaO2 levels above 60 mmHg (correct)

    • Where are the respiratory centers located in the brain stem?

  • Mid-brain only
  • Mid-brain + Pons + Medulla oblongata (correct)
  • Pons only
  • Medulla oblongata only

    • Which collection of neurons is responsible for inspiratory function?

    <p>DRN (Dorsal Respiratory Neurons) (B)</p> Signup and view all the answers

    Which nerves transmit signals to the diaphragm for contraction?

    <p>(C3-C5) Spinal Nerves (C)</p> Signup and view all the answers

    What is the role of the phrenic nerve in breathing control?

    <p>Transmit signals to the diaphragm for contraction (D)</p> Signup and view all the answers

    What happens to ventilation when PaO2 is increased above 60?

    <p>It will not be affected (A)</p> Signup and view all the answers

    What is the expected effect on ventilation if PaCO2 exceeds 40?

    <p>Hyperventilation (D)</p> Signup and view all the answers

    What happens to PaCO2 levels if ventilation decreases?

    <p>Increase (D)</p> Signup and view all the answers

    What contributes to activating the phrenic neurons for ventilation?

    <p>Increased CO2 levels (A)</p> Signup and view all the answers

    How does CO2 affect the chemo-sensitive area in the medulla?

    <p>Activates DRN (C)</p> Signup and view all the answers

    What is the outcome of an increase in H+ levels due to acidosis?

    <p>Activation of phrenic neurons (D)</p> Signup and view all the answers

    What is the main function of the Pneumotaxic center located in the upper 1/3 of the pons?

    <p>Switches off DRN (B)</p> Signup and view all the answers

    What is the role of the Apneustic center located in the lower 1/3 of the pons?

    <p>Switches on DRN (C)</p> Signup and view all the answers

    What activates the chemo-sensitive area in the medulla responsible for regulating breathing?

    <p>Acidosis (↑H+) (C)</p> Signup and view all the answers

    Where are the carotid bodies located and what do they sense?

    <p>Carotid artery, sense PaO2 (C)</p> Signup and view all the answers

    What is hyper ventilation and when does it occur?

    <p>Trying to match alveolar air composition with outside air (B)</p> Signup and view all the answers

    How can PAO2 be increased above 150?

    <p>Increase ventilation so that O2 intake exceeds uptake (D)</p> Signup and view all the answers

    How does the Apneustic center in the lower 1/3 of the pons affect the Dorsal Respiratory Nucleus (DRN)?

    <p>It switches on DRN (A)</p> Signup and view all the answers

    What is the role of the chemo-sensitive area in the medulla?

    <p>Senses changes in H+ and adjusts breathing accordingly (D)</p> Signup and view all the answers

    Why is the carotid body considered more important than the aortic body?

    <p>Because it sends impulses to DRN about PaO2 (D)</p> Signup and view all the answers

    What is the primary function of the Pneumotaxic center in the upper 1/3 of the pons?

    <p>To switch off DRN (B)</p> Signup and view all the answers

    Why is diaphragm contraction considered voluntary?

    <p>Due to signals from periphery affecting DRN (C)</p> Signup and view all the answers

    How does hyper ventilation affect PAO2 levels?

    <p>Raises PAO2 above 150 (A)</p> Signup and view all the answers

    What happens when there is acidosis (↑H+) in relation to breathing control?

    <p>[H+] increases, activating DRN and increasing ventilation (C)</p> Signup and view all the answers

    Which feedback mechanism involves signals from lung and arterial systems acting on DRN?

    <p>[Periphery] modulation (C)</p> Signup and view all the answers

    What happens to ventilation if PaO2 is increased above 60?

    <p>Ventilation remains unaffected (A)</p> Signup and view all the answers

    What is the effect on ventilation when PaCO2 exceeds 40?

    <p>Hyperventilation occurs to wash out CO2 (B)</p> Signup and view all the answers

    What triggers the activation of the chemo-sensitive area in the medulla responsible for regulating breathing?

    <p>Increased H+ concentration due to acidosis (C)</p> Signup and view all the answers

    If someone holds their breath, what is the initial response in terms of ventilation?

    <p>Ventilation stops briefly (A)</p> Signup and view all the answers

    What is the outcome if ventilation decreases?

    <p>Increased H+ concentration (C)</p> Signup and view all the answers

    Under what condition does CO2 cross the blood-brain barrier?

    <p>During hypoventilation (B)</p> Signup and view all the answers

    Which molecule indirectly facilitates CO2 crossing membranes in the brain's regulation of breathing?

    <p>$H^+$ (D)</p> Signup and view all the answers

    What is the primary response when PaCO2 levels increase above 40?

    <p>Hypercapnia leads to hyperventilation (B)</p> Signup and view all the answers

    Why does PaCO2 becoming more than 40 lead to hyperventilation?

    <p>To reduce CO2 levels in the blood (B)</p> Signup and view all the answers

    What drives the negative feedback mechanism for ventilation?

    <p>Increased H+ concentration (acidosis) (B)</p> Signup and view all the answers

    What is the main purpose of controlling breathing?

    <p>To maintain normal ABGs and homeostasis (A)</p> Signup and view all the answers

    Which part of the brain stem consists of the mid-brain, pons, and medulla oblongata?

    <p>Brain stem (B)</p> Signup and view all the answers

    What collection of neurons in the medulla oblongata is responsible for both inspiratory and expiratory functions?

    <p>Ventral respiratory neurons (VRN) (B)</p> Signup and view all the answers

    What is the primary role of spinal nerves (C3-C5) in breathing control?

    <p>Transmitting signals to the diaphragm (A)</p> Signup and view all the answers

    Which factor does NOT impact the controller or feedback systems related to breathing?

    <p>Decreased PaCO2 levels (B)</p> Signup and view all the answers

    What is the outcome of a decrease in H+ (H ion) levels in the body?

    <p>Increased ventilation (A)</p> Signup and view all the answers

    How does the brain stem contribute to controlling respiration?

    <p>By coordinating mid-brain and pons functions (A)</p> Signup and view all the answers

    What is the primary purpose of controlling breathing?

    <p>Maintenance of ABGs (O2, CO2, H+) (B)</p> Signup and view all the answers

    What happens if PaO2 levels are above 60 mmHg?

    <p>No effect on the respiratory centers (D)</p> Signup and view all the answers

    Where are the inspiratory and expiratory neurons located within the medulla oblongata?

    <p>Dorsally and ventrally (A)</p> Signup and view all the answers

    Which part of the brain stem consists of mid-brain, pons, and medulla oblongata?

    <p>Brainstem (B)</p> Signup and view all the answers

    What characterizes the nature of the feedback system in breathing control?

    <p>Increase in H+ levels (A)</p> Signup and view all the answers

    Which collection of neurons is responsible for both inspiratory and expiratory functions within the medulla oblongata?

    <p>Ventral respiratory neurons (C)</p> Signup and view all the answers

    What happens to the ventilation if PaO2 is increased above 60?

    <p>No effect on ventilation (B)</p> Signup and view all the answers

    Why does PaCO2 becoming more than 40 lead to hyperventilation?

    <p>To wash out excess CO2 (B)</p> Signup and view all the answers

    What happens to CO2 levels when alveolar ventilation is increased?

    <p>CO2 levels decrease until 0 (A)</p> Signup and view all the answers

    What drives the negative feedback mechanism for ventilation?

    <p>Increased PaCO2 levels (A)</p> Signup and view all the answers

    Which molecule indirectly facilitates CO2 crossing membranes in brain regulation?

    <p>H+ (C)</p> Signup and view all the answers

    What is the primary function of H+ in the chemo-sensitive area of the medulla?

    <p>Activating DRN (B)</p> Signup and view all the answers

    How can you increase PAO2 above 150?

    <p>Increase O2 uptake from alveoli (B)</p> Signup and view all the answers

    Which center in the medulla is sensitive to changes in [H+] and triggers the activation of DRN for increased ventilation?

    <p>Chemo-sensitive area (A)</p> Signup and view all the answers

    What does hyper ventilation aim to achieve in terms of the composition of air in the alveoli?

    <p>Increase PAO2 (D)</p> Signup and view all the answers

    Which feedback mechanism involves signals from the lung and arterial systems acting on DRN?

    <p>Periphery to Dorsal Respiratory Nucleus (DRN) (A)</p> Signup and view all the answers

    What happens in the medulla when there is acidosis (↑H+), leading to increased ventilation?

    <p>Activation of chemo-sensitive area (D)</p> Signup and view all the answers

    What is the role of aortic bodies and carotid bodies in regulating PaO2 levels?

    <p>Acting as sensory organs for detecting PaO2 levels (C)</p> Signup and view all the answers

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