- The peripheral chemoreceptors are specialized sensory receptors responsible for detecting changes in the chemical composition of the blood, particularly the levels of oxygen (O₂), carbon dioxide (CO₂), and pH.
- These chemoreceptors play a crucial role in regulating respiratory activity to maintain homeostasis.

- The primary locations of peripheral chemoreceptors are the carotid bodies and aortic bodies.
- The carotid bodies are situated at the bifurcation of the common carotid arteries, while the aortic bodies are located along the aortic arch.
- These structures are highly sensitive to decreases in arterial oxygen partial pressure (hypoxemia), increases in carbon dioxide, and changes in blood pH.

- When peripheral chemoreceptors detect a drop in oxygen levels or altered pH/CO₂ levels, they send signals via the glossopharyngeal nerve (from carotid bodies) and the vagus nerve (from aortic bodies) to the respiratory centers in the brainstem, particularly the medulla oblongata, to increase ventilation.

- In contrast, central chemoreceptors, located in the medulla oblongata, respond primarily to changes in the pH of cerebrospinal fluid, which indirectly reflects CO₂ levels in the blood.

The hypothalamus and pulmonary alveoli are not sites of primary chemoreceptor activity.

Reference: Ganong's Review of Medical Physiology, 26th Edition, Chapter 22: Respiratory System: Neural Control of Respiration