L4 Central Control of Respiration

Question 1

In which region of the CNS is respiration mostly controlled?

Answer 1

Medulla oblongata - two regions of control:

1) Inspiratory centre
2) Expiratory centre

The neurons here set the basic rhythm of respiration.

Question 2

Impulses from the inspiratory centre of the medulla oblongata are carried to the muscles of inspiration via which nerves?

Answer 2

Intercostal nerves

Phrenic nerves

Question 3

Which 2 regions of the pons function together to regulate the inspiratory centre?

Answer 3

Apneustic centre (stimulates inspiratory centre)

Pneumotaxic centre (inhibits apneustic centre and inhibitory centre)

Question 4

What is the Hering Breuer reflex?

Answer 4

Stretch receptors in walls of bronchi are activated during inspiration and send action potentials via vagus nerve to medulla oblongata. These action potentials inhibit the inspiratory centres and allow expiration.

During expiration, the stretch receptors are inactivated, allowing activation of the inspiratory centres.

Question 5

What are the two types of chemoreceptors responsible for control of respiration? Where are they located?

Answer 5

1) Central chemoreceptors (chemosensitive area of medulla oblongata)
2) Peripheral chemoreceptors (carotid bodies and aortic bodies)

Question 6

How are peripheral chemoreceptors in the carotid bodies connected to the respiratory centres of the brain?

Answer 6

Via glossopharyngeal nerve

Peripheral chemoreceptors in aortic bodies are connected via vagus nerve

Question 7

How are peripheral chemoreceptors in the aortic bodies connected to the respiratory centres of the brain?

Answer 7

Via vagus nerve

Peripheral chemoreceptors in carotid bodies are connected via glossopharyngeal nerve

Question 8

What do chemoreceptors respond to?

Answer 8

Changes in concentrations of H ions (pH) and oxygen

Question 9

What is hyper/hypocapnia?

Answer 9

Excessive/reduced CO2 in the blood

Question 10

How are CO2 levels in the blood measured by our bodies?

Answer 10

Central and peripheral chemoreceptors do not directly measure CO2, but it is indirectly monitored by measuring blood pH.

Question 11

Would an increase in blood pH increase or decrease respiratory rate?

Answer 11

Increase in pH (less acidic) results in decreased respiratory rate

Question 12

Would a decrease in blood pH increase or decrease respiratory rate?

Answer 12

Decrease in pH (more acidic) results in increased respiratory rate