Chemical Ventilation

Question 1

Where are central chemoreceptors found and what do they detect?

Answer 1

Found in medulla, detect concentrations of CO2 and H+

Question 2

Where are peripheral chemoreceptors found and what do they detect?

Answer 2

Found in arch of aorta and carotid bodies, detect concentration of O2 and pH (pH only detected by carotid bodies, not aortic)

Question 3

When is hyperventilation triggered?

Answer 3

Hyperventilation triggered when arterial blood O2 drops below 13.3 mmHg

Question 4

Describe how respiratory acidosis arises. What is the compensation for this?

Answer 4

. Hypoventilation means increase in CO2 in blood
. Increased CO2 means increased H+ ions, which decreases blood pH
. Kidneys compensate by increasing excretion of H+ and increasing reabsorption of HCO3-

Question 5

Describe how respiratory alkalosis arises. What is the compensation for this?

Answer 5

. Hyperventilation means decrease in CO2 in blood
. Decreased CO2 means decreased H+ ions, which increases blood pH
. Kidneys compensate by increasing H+ reabsorption and decreasing HCO3- excretion

Question 6

When does metabolic acidosis occur? How is this rectified?

Answer 6

. Uncontrolled diabetes

. Increased ventilation to get rid of CO2 and increase blood pH

Question 7

When does metabolic alkalosis occur? How is this rectified?

Answer 7

. Vomiting

. Decreased ventilation to increase CO2 and decrease blood pH

Question 8

Give the order of importance of ventilation stimuli.

Answer 8

1) CO2
2) pH
3) O2

Question 9

Which receptors are most sensitive to changes in pCO2?

Answer 9

. Central chemoreceptors most sensitive (levels held within 0.3kPa)
. Peripheral chemoreceptors less sensitive (levels held within 1.3 kPa)