Physiology of Breathing Control
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Questions and Answers

Which ancient physician observed the effects of spinal cord injuries on breathing?

  • Soranus
  • Galen (correct)
  • Asclepius
  • Hippocrates

    • What is the primary function of the pneumotaxic centre?

  • Regulates the expiratory phase
  • Triggers apnea
  • Inhibits the inspiratory phase (correct)
  • Stimulates the inspiratory phase

    • What is the effect of sectioning the spinal cord at the level of the pons?

  • Gasping
  • Apnea
  • Eupnea
  • Apneusis (correct)

    • Which nucleus is responsible for prolonging the inspiratory phase?

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

    What is the role of the dorsal respiratory group?

    <p>Regulates the expiratory phase</p> Signup and view all the answers

    What is the name of the ancient Greek city where Galen practiced medicine?

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

    What is the term for normal, unlabored breathing?

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

    Which of the following is NOT a part of the brain stem?

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

    What is the response to stimulation of nasal trigeminal nerve endings?

    <p>Sneeze reflex</p> Signup and view all the answers

    Which part of the brain is responsible for the central pattern generator?

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

    What is the function of the pneumotaxic centre?

    <p>To regulate breathing rate</p> Signup and view all the answers

    What is the main principle of chemical control of ventilation?

    <p>Ventilation must be matched to metabolism</p> Signup and view all the answers

    What is the function of the dorsal respiratory group?

    <p>To stimulate inspiration</p> Signup and view all the answers

    What type of receptors detect changes in lung volume and pressure?

    <p>Stretch receptors</p> Signup and view all the answers

    What is the response to stimulation of pain receptors in the trigeminal region and larynx?

    <p>Apnoea or spasm</p> Signup and view all the answers

    What is the function of the apneustic centre?

    <p>To inhibit breathing</p> Signup and view all the answers

    What is the effect of combining hypoxia and hypercapnia?

    <p>The combined effect is greater than the sum of the individual effects.</p> Signup and view all the answers

    What is the primary stimulus for respiration?

    <p>CO2 levels</p> Signup and view all the answers

    Where are the central chemoreceptors located?

    <p>Ventrolateral surface of medulla</p> Signup and view all the answers

    What is the relationship between CO2 and O2 levels in terms of respiration?

    <p>They have a synergistic effect.</p> Signup and view all the answers

    What is the effect of high CO2 levels on respiration?

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

    What is the location of the chemosensitive areas in relation to the cranial nerves?

    <p>Near the exit of cranial nerves IX and X</p> Signup and view all the answers

    What is the effect of inflation on inspiration in the Hering-Breuer inflation reflex?

    <p>It inhibits inspiration</p> Signup and view all the answers

    Which type of receptors are stimulated by increased alveolar wall fluid and oedema?

    <p>Juxtapulmonary receptors</p> Signup and view all the answers

    What is the effect of stimulating irritant receptors in the trachea?

    <p>It leads to cough</p> Signup and view all the answers

    What is the function of proprioceptive afferents in respiratory muscles?

    <p>To help cope with increased load</p> Signup and view all the answers

    What is the effect of deflation on inspiration in the deflation reflex?

    <p>It stimulates inspiration</p> Signup and view all the answers

    What is responsible for deep augmented breaths seen every 5-20 minutes at rest?

    <p>Proprioceptive afferents</p> Signup and view all the answers

    What is the primary location of the peripheral chemoreceptors that respond to changes in PO2 and PCO2?

    <p>Carotid and aortic bodies</p> Signup and view all the answers

    What is the effect of an increase in PCO2 or H+ on the peripheral chemoreceptors?

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

    What type of cells are rich in neurotransmitters and contact axons in the peripheral chemoreceptors?

    <p>Type 1 or glomus cells</p> Signup and view all the answers

    What is the approximate percentage of response to PCO2 accounted for by the peripheral chemoreceptors?

    <p>20%</p> Signup and view all the answers

    What is the term for the breathing pattern characterized by alternating periods of rapid breathing and apnea?

    <p>Cheyne-Stokes respiration</p> Signup and view all the answers

    What is the primary stimulus for the peripheral chemoreceptors?

    <p>Partial pressure of oxygen in the blood</p> Signup and view all the answers

    What is the term for the adaptation to chronic hypercapnia, resulting in a loss of CO2 drive?

    <p>Loss of CO2 drive</p> Signup and view all the answers

    What is the location of the peripheral chemoreceptors that are very small but have a high blood flow?

    <p>Carotid body</p> Signup and view all the answers

    Study Notes

    Control of Ventilation

    • Describe the source of the rhythm to breathe and the signals that affect this
    • Neural control involves the brain stem, lung receptors, and other inputs
    • Chemical control responds to changes in PCO2, PO2, and pH through central and peripheral chemoreceptors

    Brain Stem

    • The brain stem is essential for breathing, as observed by Galen, a Greek physician
    • The cervical region sends information necessary for breathing
    • The pneumotaxic center inhibits the inspiratory phase, while the apneustic center prolongs inspiration

    Lung Receptors

    • Juxtapulmonary "J" receptors are located in alveolar/bronchial walls, close to capillaries
    • Stimulated by increased alveolar wall fluid, oedema, pulmonary congestion, microembolisms, and inflammatory mediators
    • Causes apnoea or rapid shallow breathing, fall in heart rate and blood pressure, laryngeal constriction, and relaxation of skeletal muscles
    • Irritant receptors are found throughout airways, stimulated by irritant gases, smoke, dust, inflammation, and rapid large inflations and deflations
    • Proprioceptive afferents are located in respiratory muscles, stimulated by shortening and load of respiratory muscles

    Chemoreceptors

    • Central chemoreceptors are located in the ventrolateral surface of the medulla, near the exit of C IX and X
    • Peripheral chemoreceptors are found in the carotid and aortic bodies, responding to changes in PO2, PCO2, and pH
    • Carotid bodies are small but have high blood flow, comprising type 1 (glomus) and type 2 (sheath) cells

    Response to Chemical Stimuli

    • The CO2 response curve shows a synergistic relationship between PaO2 and PaCO2
    • Acidosis and alkalosis affect the CO2 response curve
    • Hypoxia stimulates breathing, with a synergistic effect when combined with hypercapnia

    Breathing Disorders

    • Loss of CO2 drive can lead to chronic hypercapnia and adaptation
    • Cheyne-Stokes respiration is associated with heart failure, stroke, and altitude sickness
    • Central sleep apnoea is characterized by an inability to breathe, often due to neuromuscular disorders

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    Description

    This quiz covers the neural and chemical control of ventilation, including the brain stem's role and the signals that affect breathing rhythm.

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