Describe the Location and Function of the Central and Peripheral Chemoreceptors

where are the peripheral chemoreceptors located

* Located in the body and not the brain
* Situated very close to the baroreceptors


* Situated in the carotid and aortic bodies

what do peripheral chemoreceptors do

Monitor the PaO2, PaCO2 and arterial \[H+\]

blood supply to peripheral chemoreceptors

They get a very high blood supply

what are the carotid bodies innervated by

Carotid bodies innervated by cranial nerve IX

what are the aortic bodies innervated by

Aortic bodies innervated by the vagus nerve (CN X)

are the aortic bodies more important in the foetus or the animal after it is born

Aortic bodies not that important in animals after they are born - of more importance in the foetus

what do peripheral chemoreceptors do when PO2 drops

Increase action potential generation when PO2 drops → signals respiratory centre to increase ventilation

which is a more sensitive measure of ventilation - oxygen or carbon dioxide

Oxygen is not a very sensitive measure of ventilation - therefore, the carotid bodies don't significantly increase their output of action potentials until your partial pressure of oxygen has dropped all the way down to about 70.

Carbon dioxide is much more sensitive.

location of central chemoreceptors

Exact location uncertain

what do central chemoreceptors monitor

Monitor PaCO2 only

what do the central chemoreceptors detect

* CO2 crosses the blood brain barrier and carbonic anhydrase acts to generate HCO3- and H+
* The chemoreceptors detect this H+
* PaCO2 detected by central chemoreceptors is the most important factor governing respiration under normal circumstances

why is PaO2 less sensitive

PaO2 less sensitive as haemoglobin saturation nearly 100% until PaO2 drops below 70mmHg