PRACTICE QUESTIONS______

1. The rhythmicity of breathing is thought to originate solely in the:

a. Ventral respiratory group of medullary neurons

b. Apneustic center

c. Pons

d. Rapidly adapting pulmonary stretch receptors

e.

2. Which of the following receptors have afferent nerve fibers in the glossopharyngeal nerve?

a. Carotid bodies

b. Slowly adapting pulmonary stretch receptors

c. Aortic bodies

d. Intercostal stretch receptors

e. Rapidly adapting pulmonary stretch receptors

3. Which of the following statements correctly describes the carotid bodies?

a. Carotid bodies can increase ventilation in response to low Pao₂, but not in response to an increase in Paco₂.

b. Carotid bodies have a low blood flow/metabolism ratio.

c. Chemoreception is thought to occur in the susten­tacular cells.

d. Carotid bodies are located near the bifurcation of the internal and external carotid arteries.

e. All the above

4. The duration of inhalation:

a. Is independent of chemical drive.

b. Is independent of chemical drive only after vagotomy.

c. Is determined by the ventral respiratory group of neurons.

d. Is shortened by vagotomy.

5. The ventilatory response to a change in Paco₂:

a. Is mediated through a change in pH of inter­stitial fluid bathing the central chemosensitive neurons.

b. Is accentuated in metabolic acidosis, because there is less buttering of the interstitial fluid around the central chemoreceptor.

c. Is modified during exercise, so Paco₂ remains constant despite a large increase in CO₂ production.

d. Can occur in the absence of the peripheral chemo­receptors.

e. All the above

6. Which of the following receptors are thought to initiate a cough in response to mechanical deformation of the airway?

a. Iuxtacapillary receptors

b. Rapidly adapting stretch receptors

c. Slowly adapting stretch receptors

d. Intercostal tendon organs

e. None of the above