What is the first component of a homeostatic control system?

• A. Receptor
• B. Control center
• C. Effector
• D. Afferent pathway

Answer: (A)

The first component is the receptor. It acts as the sensor that detects a deviation in a variable, such as temperature or blood glucose, from its normal set point. When the receptor senses this change, it converts it into a signal that travels to the control center through an afferent pathway. The control center then compares the current value to the set point and determines the appropriate response, which is carried out by an effector via the efferent pathway to bring the variable back to normal. For example, when body temperature rises, temperature receptors sense the change and send signals to the brain, triggering cooling responses like sweating and vasodilation.