Control of Respiration

Question 1

Where is the respiratory center in the brain?

Answer 1

The medulla

Question 2

Where are peripheral chemoreceptors located?

Answer 2

Carotid bodies

Question 3

Peripheral chemoreceptors increase ventilation in response to three things: ____________.

Answer 3

low arterial oxygen, high arterial P(CO2), or high arterial [H+]

Question 4

Control of respiration through low arterial oxygen is relatively insensitive until _________.

Answer 4

arterial oxygen decreases to

Question 5

Where are the central chemoreceptors located?

Answer 5

On the ventral surface of the medulla

Question 6

The central chemoreceptors have ______ receptors.

Answer 6

[H+]

Question 7

Protons do not cross the blood-brain barrier to touch the medulla, rather _________.

Answer 7

CO2 diffuses into the CSF and converts to carbonic acid

Question 8

The sensing of protons is relatively ________ in the central chemoreceptor system (unlike the peripheral system).

Answer 8

slow, because the CSF does not have carbonic anhydrase

Question 9

The proton sensor on the medulla controls about ______ percent of the ventilatory response to chronically high P(CO2).

Answer 9

80

Question 10

Which ventilatory response kicks in under conditions of low oxygen pressure?

Answer 10

Peripheral oxygen receptors (in the carotid bodies)

Question 11

Which ventilatory response kicks in under conditions of rapidly increased CO2?

Answer 11

Peripheral CO2 receptors

Question 12

Which ventilatory response kicks in under conditions of metabolic acid/base insults?

Answer 12

Peripheral proton receptors

Question 13

Which ventilatory response kicks in under conditions of chronically high CO2 levels?

Answer 13

Central chemoreceptors

Question 14

The __________ is the most important day-to-day regulator of ventilation.

Answer 14

medullary chemoreceptor system

Question 15

The ______ response in exercise is controlled by CO2, while the _____ response is controlled by protons.

Answer 15

early/moderate; late/extreme

Question 16

The _________ generates breathing without input from other areas.

Answer 16

medulla

Question 17

There are both P(O2) and P(CO2) sensors in the aortic arch and carotid bodies, but [H+] sensors are only in the ________.

Answer 17

carotid bodies

Question 18

The only pH detector that can modulate ventilation is _____.

Answer 18

the carotid bodies

Question 19

Describe the integrated response to high altitude.

Answer 19

The initial drop in Pa(O2) stimulates the peripheral O2 receptors to increase the ventilation rate. The increased ventilation rate lowers the P(CO2), which raises the pH of the CSF and causes the medulla to limit the ventilation rate. Excretion of HCO3- by the kidneys reduces the CSF’s pH and allows the ventilation to increase beyond its first levels.