Chemical control of breathing

Question 1

What are the 3 goals of the respiratory system?

Answer 1

Ensure alveolar ventilation is sufficient to maintain normal blood gases
To adapt ventilation to changing environment or metabolic needs
Integrate ventilation with non-respiratory activates like talking or eating

Question 2

What is the respiratory control system?

Answer 2

The respiratory centre medulla

Question 3

What is the respiratory centre medulla?

Answer 3

Autonomous breathing generator - used when sleeping

Question 4

What feeds back to the respiratory centre medulla that affects respiratory muscles?

Answer 4

Chemoreceptors, cerebrally rotex, mechanoreceptors

Question 5

What do peripheral chemoreceptors respond to?

Answer 5

Changes in O2 concentration in the arterial blood

Question 6

What 2 locations to the peripheral chemoreceptors occupy?

Answer 6

Aortic bodies along the aortic arch

Carotid bodies at the bifurcation of internal and external carotid arteries

Question 7

Which chemoreceptors control all of the bodies O2 response?

Answer 7

Peripheral

Question 8

Why do the peripheral chemoreceptors respond quickly?

Answer 8

There is no need for any gas exchange

Question 9

How does sensory information from the aortic bodies reach the medullary respiratory centre?

Answer 9

Vagus nerve

Question 10

How dis sensory information from the carotid bodies reach the medullary respiratory centre?

Answer 10

Glossopharyngeal nerve

Question 11

Why do the glomus cells in the carotid bodies need lobe well perfused?

Answer 11

So any change in oxygen concentration is picked up

Question 12

Why do glomus cells in the carotid bodies need a high metabolic rate?

Answer 12

Means they use a lot of oxygen so any drop in oxygen is picked up quickly

Question 13

At what level of oxygen concentration does ventilation start to increase?

Answer 13

60mmHg

Question 14

What do chemoreceptors monitor?

Answer 14

CO2 levels by sensing protons

Question 15

What affect does high CO2 have on ventilation?

Answer 15

A linear increase straight away

Question 16

When does CO2 induced stimulation of ventilation stop?

Answer 16

When CO2 is below 30mmHg

Question 17

What does it mean by the effects of CO2 and O2 are more than additive - they are synergic?

Answer 17

The sum of the 2 parts is less than the result

Question 18

Why does having low oxygen and high CO2 increase ventilation more than just 1 factor?

Answer 18

They are synergic

Question 19

Why are central chemoreceptors more sensitive than peripheral?

Answer 19

Central respond to CO2 which causes an effect in ventilation straight away.
Peripheral responds to O2 which only effects ventilation when below 60mmHg

Question 20

Do pH and CO2 response of a synergic relationship what does this mean?

Answer 20

Yes

Lower pH levels increases the breathing rate and makes CO2 response more sensitive

Question 21

What affect does consciousness have in CO2 ventilatory response?

Answer 21

During sleep central chemoreceptors are less sensitive to changes in CO2

Question 22

Why can hyperventilation cause damage?

Answer 22

Reduces the partial pressure of CO2 as ventilation increases.
When partial pressure of CO2 goes below 30mmHg the ventilatory response will stop (as the body thinks no hypoxia)
No ventilatory drive