Central Chemoreceptors (PK9)

Question 1

What are central chemoreceptors sensitive to?

Answer 1

Hypercapnia

Question 2

What percentage of ventilatory response to CO2 is generated by central chemoreceptors?

Answer 2

80%

Question 3

What are central chemoreceptors inhibited by?

Answer 3

Hypoxia

Question 4

3 zones of central chemoreceptors

Answer 4

• Rostral
• Intermediate
• Caudal

Question 5

How do central chemoreceptors detect hypercapnia, and how is ventilation changed as a result?

Answer 5

• H+ cannot directly cross blood brain barrier to CSF
• Can go into equation H+ + HCO3- –> H2CO3 –> H2O + CO2
• CO2 can cross BBB
• Once in CSF, CO2 enters equation CO2 + H2O –> H2CO3 –> H+ + HCO3-
• Central chemoreceptors detect H+ formed
• Signal goes from central chemoreceptors –> medullary respiratory neurones –> adjustment of ventilation

Question 6

Why are central chemoreceptors not sensitive to metabolic acidosis/alkalosis?

Answer 6

H+ cannot cross BBB

Question 7

How does acclimatisation work?

Answer 7

pH error signal is gradually attenuated by active transport of HCO3- from blood to CSF or vice versa to buffer H+