Answer:
Sensors or sensory receptors must sense any change in blood glucose levels.
Step-by-step explanation:
A feedback system includes a receptor, control center, and effector. The receptors serve to sense the deviation from homeostasis and send the nerve impulses or chemical signals to the respective control center. The control center receives input from receptors and sends nerve impulses or chemical signals to the effectors to bring about the desired change to restore homeostasis.
Negative feedback regulation of blood sugar includes sensing the rise or drop in blood sugar levels by sensory receptors. This sensory information is sent to the control center which in turn commands the effectors (pancreas) to secrete insulin or glucagon hormones to lower down or raise the blood glucose levels. Feedback regulation does not work in the absence of any of the components (sensory receptor, control center, and effector).