4.6

Question 1

What can peripheral chemoreceptors detect the levels of?

Answer 1

• CO2
• O2
• H+

Question 2

Response of respiratory system to exercise

Answer 2

1. Increased demand for oxygen in muscle
2. Increased production of CO2 in muscle
3. Increased PaCO2 and decreased PaO2
4. Stimulation of peripheral and central chemoreceptors
5. Increase in ventilation to restore homeostasis and enable gas exchange
6. Activation of accessory muscles of breathing

Question 3

What molecule is the main driver for increase in ventilation?

Answer 3

Carbon dioxide (linear relationship)

Question 4

How are glomus cells activated when acidosis, hypercapnia, or hypoxia occur?

Answer 4

In case of CO2 or H+: presence of H+ (sometimes from ionized H2 CO3 when dealing with CO2) inhibits potassium channel, depolarizing cell, causing neurotransmitter release and thus activating afferent fibres.

Question 5

What causes central chemoreceptors to pick up on a change in breathing? How?

Answer 5

• pH decrease
• CO2 can diffuse across BBB, and after becoming carbonic acid with the help of carbonic annhydrase and then ionising, it increases [H+]