3.7. Chemical control of the respiration. Pulmonary adaptations to training.

Question 1

I. Chemical control of the respiration
1. What are the 2 types of chemical control of respiration?

Answer 1

1. Central chemoreceptors
2. Peripheral chemoreceptors

Question 2

I. Chemical control of the respiration
2. How can central chemoreceptors participate in chemical control of respiration?

Answer 2

• The most important receptor for the minute-to-minute control of breathing.
• They are extremely sensitive to changes in the pH of CSF; ↓pH of CSF (due to ↑pCO2) produces hyperventilation (↑breathing rate) and vice versa.
• Mechanism: due to BBB, H+ and HCO3- produced in blood cannot pass through. CO2, however, is permeable across BBB and also brain-CSF barrier so it enters ECF and then CSF. In CSF, CO2 is converted to H+ and HCO3-, where H+ conc is sensed. Central chemoreceptors instruct DRG to increase breathing rate to expire more CO2.

Question 3

I. Chemical control of the respiration
3A. How can peripheral chemoreceptors participate in chemical control of respiration?

Answer 3

• located in carotid and aortic bodies
• detect changes and send information to the brain stem control centers via the Vagus N to change breathing rate appropriately
• sensitive to:
  1. pO2 ↓ (hypoxia) * (PCR only chemoreceptor to respond to arterial pO2)
  2. pCO2↑
  3. pH↓
  4. [K+]↑
• Increase in breathing rate is associated with following peripheral detections:
  1.Decrease in arterial pO2 (but only after it falls below 60mmHg)
  2. Increase in arterial pCO2

Question 4

I. Chemical control of the respiration
3B. What does increase in breathing rate mean?

Answer 4

Question 5

II. How do we have Pulmonary adaptations to training?

Answer 5

• In trained persons, ↑VC, ↑TLC, ↑TV, ↑maximum ventilation.
• Exercise can increase the maximum oxygen uptake of the person which increases the mechanical power delivered.