Feedback mechanism is a control mechanism in organisms in which a change in a given factor either inhibits or stimulates processes controlling the production, release, or use of that factor.
In other words it is a response within a system (molecule, cell, organism, or population) that influences the continued activity or productivity of that system. So in essence, it is the control of a biological reaction by the end products of that reaction.
For example - An increase in blood sugar level triggers the release of the hormone insulin by the pancreas. The hormone insulin lowers blood sugar level restoring the body to its original blood glucose level in two major ways:
- it increases the ability of body cells to take in glucose from the blood
- it converts blood glucose to the compound glycogen -- this compound is also called animal starch and is stored in our liver and muscles