Negative feedback- is a control tool in our bodies, that regulates the amount of substance the body can. When an effector gets the message that the body is producing too much of a substance negative feed back, inhibits the amount of production of that substance until it reaches a certain level again.

Describe negative feedback and how insulin is controlled by a negative feedback inhibition.
When you eat a meal your blood glucose rises from the sugars that your eating in the food. To regulate the blood sugar beta cells of islets of Langerhans in the pancreas secrete insulin ( polypeptied hormone) that encourages the cells to soak up the glucose. When this happens the blood glucose level decreases and so does the production on insulin. This is how a negative feedback mechanism works to control the right level of glucose in our bodies.

To explain better here is a "you tube" video so you can visualize the pancreas secreting insulin.

Why is it essential that insulin and other molecules be regulated?
It is Essential for our bodies to regulate insulin and other molecules because it keeps the environment in the body stable so that we can function normally in everyday life.

Fun Fact:If one functional kidney is missing from birth, the other kidney can grow to reach a size similar to the combined weight of two kidneys (about one pound)!

Thanks to:
Human physiology 11th edition -McGraw-Hill
Anatomy and Physiology 4th edition-Mcgraw-Hill