Expansion
Peripheral chemoreceptors sense oxygen; central chemoreceptors sense carbon dioxide
Expansion
Peripheral chemoreceptors - carotid and aortic bodies
- Sense low arterial oxygen tension, high carbon dioxide and low pH
- Afferents in the glossopharyngeal and vagus nerves
- Respond only when the partial pressure of oxygen falls below about 8 kPa (60 mmHg)
- Cardiovascular effect: vasoconstriction and a rise in blood pressure
Central chemoreceptors - ventral medulla
- Sense carbon dioxide, indirectly through the pH of cerebrospinal fluid
- Responsible for the majority of the normal ventilatory drive
An important consequence: because peripheral receptors sense tension and not content, they are not stimulated by anaemia or by carbon monoxide poisoning, where oxygen content is low but partial pressure is normal. That is why such patients may not be breathless despite dangerous tissue hypoxia.