Final answer:
A control mechanism maintaining homeostasis in response to abnormal substance levels is called a negative feedback loop, involving a stimulus, sensor, control center, and effector. It helps maintain stable internal conditions by adjusting physiological processes.
Step-by-step explanation:
A control mechanism that monitors levels of a substance and triggers a change in physiology to bring levels back to normal when a substance is not normal is known as a negative feedback loop. This involves four main components: a stimulus, a sensor (or receptor), a control center, and an effector. The control center processes information received from the sensor and sends signals to the effector to take the necessary action to restore balance, i.e., maintain homeostasis.
For example, in regulating blood glucose levels, a rise in blood glucose is the stimulus detected by the pancreas. The pancreas (acting as the control center) releases insulin, leading to a decrease in blood glucose levels (the effector action). Conversely, if blood glucose levels are too low, the pancreas releases glucagon to increase the levels, thus maintaining homeostasis through a negative feedback mechanism.
Negative feedback loops are essential in maintaining the stable internal conditions required for proper function of the body. Disorders like diabetes can arise from a breakdown in these homeostatic mechanisms.