Respiratory control

Question 1

Negative feedback

Answer 1

Controls ventilation to maintain normal arterial blood gases and to minimise work of breathing

Question 2

Basic respiratory rhythm

Answer 2

Generated by neurones in the brainstem, this rhythm is modulated by ventilatory reflexes.

Question 3

Resting breathing

Answer 3

Through inspiratory drive, with expiration being passive during quiet breathing.

Question 4

Arterial pCO2

Answer 4

A major factor determining ventilatory drive at rest.

Question 5

Ventilatory response to hypoxia

Answer 5

Depends on arterial pCO2 and is not prominant until arterial pO2 falls below 60mmHg

Question 6

Arterial chemoreceptors

Answer 6

Sense pO2, pCO2, and pH. Central chemoreceptors only sense arterial pCO2.

Question 7

Vagal nerve endings

Answer 7

Sensitive to strech in the lung to fine tune rate and depth of breathing.

Question 8

Hyperventilation

Answer 8

High pCO2 increases ventilation, hyperventilation occurs, eventuallys leads to breathing stopping as all CO2 has been blown off, removing the stimulus to breathe.

Question 9

Hering-Breuer inflation reflex

Answer 9

Increase in duration of expiration after hyper inflation (stretch) of the lung. Strech receptors, vagally mediated with afferent info from the intercostal muscles projecting via the vagus to higher centres.

Question 10

Hering-Breuer deflation reflex

Answer 10

Decrease in duration of expiration after hyper deflation of the lung. Stretch receptors, vagally mediated with afferent info from the intercostal muscles projecting via the vagus to higher centres

Question 11

Irritant receptors

Answer 11

In trachea and bronchi, cause cough in response to noxious stimuli

Question 12

Juxta-capillary receptors near alveoli

Answer 12

Unmyelinated c fibres, stimulated hy hyperinflation,cessation of breathing, followed hy rapid breathing.