The carotid body is the more important of the two and is situated at the division of the common carotid artery into the external and internal carotid arteries in the neck. The aortic body is found on the aortic arch. The output from the carotid body is thought to provide information to allow immediate regulation of breathing, breath by breath, by the respiratory centre. Breathing can be influenced by other parts of the brain. Intensely emotional situations, for example, distressing sights, will also cause hyperventilation.
Hyperventilation is also part of the response to massive blood loss.
This response is co-ordinated by the autonomic system in the hypothalamus and the vasomotor centre in the brain stem. There are various receptors in the lung that modify breathing. Receptors in the wall of the bronchi respond to irritant substances and cause coughing, breath holding and sneezing. In the elastic tissues of the lung and the chest wall are receptors that respond to stretch. The exact function of these receptors is not fully understood but are thought to be responsible for various reflexes that have been discovered in laboratory studies of animals.