Final answer:
Chemoreceptors located in the aortic and carotid sinuses, known as peripheral chemoreceptors, and central chemoreceptors in the brain are responsible for detecting hypercapnia and signaling the body to adjust the respiratory rate.
Step-by-step explanation:
The chemoreceptors that pick up hypercapnia, which is an elevated level of carbon dioxide (CO2) in the blood, are primarily located in two areas. The first set, known as the peripheral chemoreceptors, are found in the walls of the aortic and carotid sinuses. These receptors are sensitive to significant changes in blood CO2 levels, and they provide immediate feedback to the respiratory centers to adjust the respiratory rate accordingly. Another set of chemoreceptors, known as the central chemoreceptors, are located in the brain. They monitor changes in the pH of the cerebrospinal fluid (CSF), which reflects CO2 levels, and signal the medulla oblongata to modulate breathing to regulate these levels.