5.5 Regulation of Respiration

Question 1

What is meant by neurogenic regulation?

Answer 1

Regulation that arises from the nervous system

Question 2

Which phases of the respiratory cycle do the ventral/dorsal respiratory groups in the medulla control?

Answer 2

Dorsal: Inspiration
Ventral: Inspiration and Expiration

Question 3

By which pathways do the dorsal and ventral respiratory groups exert a motor effect?

Answer 3

Respiratory motor pathways

Question 4

Structure/function of dorsal respiratory group (DRG)

Answer 4

Inspiratory neurons responsible for timing of the respiratory cycle

Question 5

Structure/function of the ventral respiratory group (VRG)

Answer 5

Neurons that influence both inspiration and expiration

Question 6

Which two centres are located within the pontine respiratory centre?

Answer 6

• Pneumotaxic centre
• Apneustic centre

Question 7

Role of pneumotaxic centre

Answer 7

Limit depth of breathing

Question 8

Role of apneustic centre

Answer 8

Delay inspiratory off-switch

Question 9

What is apneusis?

Answer 9

a disturbance of respiratory rhythm characterized by severely prolonged inspiratory effort

Question 10

Are the same neurons active at all points in the respiratory cycle?

Answer 10

• No
• Different neurons are activated at different points in the respiratory cycle, creating a repeating pattern of neuronal activation

Question 11

Describe the location and action of slow-acting stretch receptors in the respiratory system

Answer 11

• Predominantly in airways
• Act as lung volume sensor

Question 12

Describe the location and action of rapid-acting receptors in the respiratory system

Answer 12

• Located in superficial mucosal layer
• Stimulated by changes in tidal volume, breathing frequency, and compliance of the lungs

Question 13

Describe the location and role of vagal c-fibre nociceptors in the respiratory system

Answer 13

• Located in pulmonary capillaries and bronchi
• Sensitive to inflammation, irritants etc.

Question 14

List some circumstances under which PCO2 of CSF would be expected to increase

Answer 14

• Hypoventilation
• Exertion

Question 15

What has a bigger impact on alveolar ventilation: pH or PCO2?

Answer 15

PCO2

Question 16

Where are peripheral chemoreceptors located? Why is this easy to remember?

Answer 16

• They are located in the carotid bodies and aortic arch
• These are the same locations as the baroreceptors

Question 17

What are peripheral chemoreceptors sensitive to?

Answer 17

• Primarily oxygen
• Also somewhat to CO2 and H+

Question 18

By what nerve do carotid chemoreceptors send information to the dorsal respiratory area?

Answer 18

Glossopharyngeal nerve

Question 19

By what nerve do aortic chemoreceptors send information to the dorsal respiratory area?

Answer 19

Vagal nerve

Question 20

Describe the increase in alveolar ventilation as partial pressure of oxygen decreases. Why does this make sense.

Answer 20

• Exponential
• Think back to the haemoglobin saturation/PO2 graph; it increases exponentially, then levels out. As the level of oxygen dips below the plateau of haemoglobin saturation, this is when alveolar ventilation begins to increase dramatically.

Question 21

When O2, CO2, and H+ all change at once, how does this influence the change in alveolar ventilation?

Answer 21

It magnifies it

Question 22

Relate respiratory acidosis and respiratory alkalosis to hyperventilation and hypoventilation

Answer 22

Acidosis: Hypoventilation, too much CO2, too much H+, too acidic
Alkalosis: Hyperventilation, not enough CO2, not enough H+, too basic

Question 23

What is hyperpnea?

Answer 23

Increased breathing rate

Question 24

What is the first point at which motor movement stimulates an increase in breathing?

Answer 24

As an efferent motor signal travels out of the brain towards peripheral muscles, it passes the medulla, and stimulates an increase in breathing on the way down.

Question 25

How do muscles feed back to the respiratory centre to control ventilation?

Answer 25

• Proprioceptors in muscle detect metabolic activity and mechanical stretch of muscle, helping to inform changes in respiratory rate

Question 26

What are the C-fibres in the pulmonary capillaries and bronchi also called?

Answer 26

Juxtacapillary receptors