Chemical control of breathing Flashcards
What are the 3 goals of the respiratory system?
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
What is the respiratory control system?
The respiratory centre medulla
What is the respiratory centre medulla?
Autonomous breathing generator - used when sleeping
What feeds back to the respiratory centre medulla that affects respiratory muscles?
Chemoreceptors, cerebrally rotex, mechanoreceptors
What do peripheral chemoreceptors respond to?
Changes in O2 concentration in the arterial blood
What 2 locations to the peripheral chemoreceptors occupy?
Aortic bodies along the aortic arch
Carotid bodies at the bifurcation of internal and external carotid arteries
Which chemoreceptors control all of the bodies O2 response?
Peripheral
Why do the peripheral chemoreceptors respond quickly?
There is no need for any gas exchange
How does sensory information from the aortic bodies reach the medullary respiratory centre?
Vagus nerve
How dis sensory information from the carotid bodies reach the medullary respiratory centre?
Glossopharyngeal nerve
Why do the glomus cells in the carotid bodies need lobe well perfused?
So any change in oxygen concentration is picked up
Why do glomus cells in the carotid bodies need a high metabolic rate?
Means they use a lot of oxygen so any drop in oxygen is picked up quickly
At what level of oxygen concentration does ventilation start to increase?
60mmHg
What do chemoreceptors monitor?
CO2 levels by sensing protons
What affect does high CO2 have on ventilation?
A linear increase straight away
When does CO2 induced stimulation of ventilation stop?
When CO2 is below 30mmHg
What does it mean by the effects of CO2 and O2 are more than additive - they are synergic?
The sum of the 2 parts is less than the result
Why does having low oxygen and high CO2 increase ventilation more than just 1 factor?
They are synergic
Why are central chemoreceptors more sensitive than peripheral?
Central respond to CO2 which causes an effect in ventilation straight away.
Peripheral responds to O2 which only effects ventilation when below 60mmHg
Do pH and CO2 response of a synergic relationship what does this mean?
Yes
Lower pH levels increases the breathing rate and makes CO2 response more sensitive
What affect does consciousness have in CO2 ventilatory response?
During sleep central chemoreceptors are less sensitive to changes in CO2
Why can hyperventilation cause damage?
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
