Chapter 8

Question 1

What are the lung receptors?

What are the other receptors?

Answer 1

1. Pulmonary stretch receptors
   - Hering Breuer reflex
   - inflation causes expiration
   - deflation reflex: deflation of lungs causes inspiration
2. Irritant receptors - vagus nerve - bronchoconstriction and hyperpnea
3. J receptors (nonmyelinated C fibers) - vagus nerve
   - results in rapid shallow breathing
   - detects chemicals in pulmonary circulation (pulmonary edema)
4. Bronchial C fibers
   - detects chemicals in bronchial circulation
   - causes rapid shallow breathing
   - bronchoconstriction, mucus secretion

Other:

1. Irritant receptors
   - nose, naropharynx, larynx, trachea - vagus - cough/sneeze/bronchoconstriction
2. Joint and muscle receptors
3. Gamma system
   - intercostal and diaphragm
4. Arterial baroreceptors
   - increased arterial blood pressure causes reflex hypoventilation
   - decrease in blood pressure causes hyperventilation
5. Pain and temperature receptors

Question 2

What are the other receptors? (not in lung)

Answer 2

Other:

1. Irritant receptors
   - nose, naropharynx, larynx, trachea - vagus - cough/sneeze/bronchoconstriction
2. Joint and muscle receptors
3. Gamma system
   - intercostal and diaphragm
4. Arterial baroreceptors
   - increased arterial blood pressure causes reflex hypoventilation
   - decrease in blood pressure causes hyperventilation
5. Pain and temperature receptors

Question 3

What are the central controllers?

Answer 3

Brainstem

1. medullary respiratory center
   - pre-botzinger complex - pacemaker
   - dorsal respiratory group - inspiration
   - ventral respiratory group - expiration
2. Apneustic center (lower pons)
   - stimulates inspiration (apneustic gasps)
   - gets input from stretch receptors (Hering Breuer reflex)
3. Pneumotaxic center
   - inhibits inspiration

Cortex
- voluntary control

Other parts of brain
- hypothalamus and limbus

Question 4

What affects the central chemoreceptors?

Answer 4

pH of CSF

• this is affected by pCO2
• H and HCO3 don’t pass the blood brain barrier

note: cerebral vasodilation enhances diffusion of CO2 into the CSF (happens when pCO2 increases)

not sensitive to PO2

Question 5

where are the central chemoreceptors?

Answer 5

ventral surface of medulla

Question 6

What affects the peripheral chemoreceptors?

Answer 6

ARTERIAL pO2 <50-60mmhg primarily

carotid: (most important)
- pO2
- pCO2 (faster than central)
- pH (unlike central, affected by METABOLIC ACIDOSIS)

aortic

• pO2
• pCO2

Question 7

Which chemoreceptors respond to metabolic acidosis?

Answer 7

carotid

NOT CENTRAL

Question 8

What is the affector nerve for carotid? for aortic bodies?

Answer 8

carotid: glossopharyngeal
aortic: vagus

Question 9

What happens to ventilatory response to CO2 when work of breathing increased?

Answer 9

ventilatory response is reduced

Question 10

What are possible ventilation responses to exercise due to?

Answer 10

Don’t really know

• passive movement of limbs
• oscillations in arterial pO2 and pCO2
• central receptors increase ventilation to hold arterial pCO2 constant
• ventilation is linked to additional CO2 load presented to lungs in mixed venous blood
• increase in body temperature
• impulses from motor context