Biology essay on feedback mechanisms
Negative feedback causes the body to respond in such a way as to reverse the direction of a change and this tends to keep the internal environment at a constant, thus maintaining homeostasis. Sensors and receptors are what bring about a reaction to ensure conditions within the body remain favourable. Examples of negative feedback are as follows.
Blood glucose levels
The receptors of the pancreas are responsible for monitoring the blood glucose levels. The alpha-cells of the Islets of Langerhans release glucagons when glucose levels are low. Glucagons promote the conversion of glycogen into glucose; the lack of glucose can then be compensated for by the new supply of glucose brought about from glucagons. The beta cells of the Islets of Langerhans release insulin when the levels of glucose in the blood is high. Insulin promotes the conversion of glucose into glycogen and this can be stored in the liver for later use.
Fight or flight
In emergencies adrenaline is released by the body to override the homeostatic control of glucose levels and promotes the breakdown of glycogen into glucose. Adrenaline is secreted by the adrenal gland and its secretion leads to increased heart rate, breathing and metabolism. Once the