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How do chemoreceptors help control breathing?

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A pine grosbeak with pink and gray plumage perches on a branch, eating red berries among autumn foliage. — Chemoreception Animals, such as this pine grosbeak, use chemoreception to respond to chemicals that can be tasted and smelled in their environments. Many of these chemicals affect behaviors such as food preference and defense.

Chemoreceptors regulate breathing by monitoring arterial blood and brain environments to maintain stable levels of oxygen and carbon dioxide. They are categorized into two types:

Peripheral Chemoreceptors

Located in the carotid bodies and aortic bodies, these sensors respond primarily to hypoxia (low oxygen) and fluctuations in carbon dioxide partial pressure. When oxygen levels drop or carbon dioxide rises, these receptors increase their firing rate, signaling the brain to augment the rate and depth of ventilation. This process involves the release of neuroactive substances from type I cells, which stimulate sensory nerves to adjust breathing accordingly.12

Central Chemoreceptors

Situated in the brain, likely near the ventral medulla, these receptors respond to changes in the partial pressure of carbon dioxide in their immediate environment. Carbon dioxide increases the acidity of surrounding fluid, which serves as a powerful stimulant for breathing. By sensing these chemical changes, the body ensures ventilation is adjusted to restore blood gas levels to their usual state.31