Control of breathing Neural reflex Lecture 14

Question 1

Describe pulmonary stretch receptors

Answer 1

Vagal nerve ending in smooth muscle of the trachea and lower airways, stimulated by the lung inflation- slowly adapting stretch receptors If the lungs are inflated to above threshold at anytime of inspiration is immediately switched off Inhibits inspiration and promotes expiration ➡️NTS➡️PRG (suppresses DRG)

Question 2

Hering-Breurer reflex

Answer 2

Present during sleep - stops lungs overinflating

Inhibits inspiration and promotes expiration (important in individuals with low compliance)

DRG inhibited as phrenic nerve is off and PRG stimulated (inhibits DRG and turns off inspiraiton)

Remove stretch receptors and PRG for longer inspiraiton

Role in exercise - makes you breathe more rapidly

Question 3

Describe lung-irritant receptors

Answer 3

Vagal nerve endings between epithelia of trachea and lower airways Stimulated by noxious gases, smoke, dust, cold air Rapidly adapting receptors Bring about- rapid shallow breathing -long, deep augmented breaths

Question 4

Describe pulmonary C receptors/J receptors

Answer 4

In bronchial walls and alveolar walls close to capillaries Usually silent- stimulated by mechanical distortions and increase in interstitial fluid Evoke rapid shallow breathing

Question 5

Describe the nerve control in the nose and upper airways

Answer 5

Mechanical and chemical stimulation Evoke sneezing, coughing and bronchoconstriction apnoea and bradycardia Liquid evokes diving reflex

Question 6

Describe proprioreceptors in neural control

Answer 6

In muscle spindles in intercostal muscles Allow for increased force of inspiration and expiration if movement is impeded Responsible for the sensation of dyspnoea if large effort is required

Question 7

Describe atrial baroreceptors

Answer 7

Increase in blood pressure leads to reflex hypoventilation Decrease in blood pressure leads to reflex hyperventilation