What is the role of the receptor in homeostatic control?

• A. It monitors the environment and responds to changes by sending information to the control center.
• B. It determines the set point.
• C. It issues commands to muscles or glands.
• D. It carries information away from the control center.

Answer: (A)

Receptors are the sensing elements of homeostatic control. They monitor internal and external conditions and detect deviations from the normal state. When a change is detected, receptors send information to the control center, providing the input the body needs to decide whether a response is required. The control center then compares that input to a set point and, if needed, activates effectors to bring conditions back toward balance. Receptors don’t set the set point, don’t issue commands themselves, and don’t carry information away from the control center—that last part is done by the efferent pathway to the organs that execute the response. For example, temperature receptors detect heat or cold and relay signals to the brain, which can trigger sweating or shivering to restore normal temperature.