Importance of negative feedback Negative feedback is when a departure from a norm initiates changes which restore a system to the norm. The first example of the importance of negative feedback is in control of the heart rate. The heart is monogenic, meaning that each heartbeat is initiated by senatorial node inside the heart itself, not by nerve impulses from the central nervous system. After exercise, the concentration of carbon dioxide in the blood is high, meaning that the pH in the blood is low. Competitors in the carotid arteries and aortic walls detect this change in PH.
They increase the free ounce of nerve impulses to the centre in the medulla obbligato. The centre increases the free ounce of impulses via the sympathetic nervous system to the SAN. The sympathetic neuroses secrete noradrenalin, which binds to receptors on the SAN. This causes the heart rate to increase in order to return pH levels back to normal. This is an example of negative feedback as a change is detected and a corrective mechanism sets in to restore the normal level. The maintenance of H levels in the blood is very important as pH affects enzyme activity as it can denature enzymes; enzymes control the rate of metabolic reactions.
This shows that negative feedback is important in the human body. Secondly, it is important to maintain core body temperature and this is controlled by negative feedback. Changes in body temperature are detected by thermometers. The hypothalamus has receptors which detect internal temperature. These thermometers send nerve impulses to a heat loss or gain centre in the hypothalamus which in turn sends impulses to the effecter. For example, if the environment surrounding an endothermic is very hot.
This high temperature will be detected by thermometers in the skin. They send nerve impulses to the hypothalamus in the brain which then sends nerve impulses to the heat loss centre, also in the hypothalamus. This will cause an effecter to produce an appropriate response such as vacillation (so more heat is radiated away from surface of skin), increased sweating (so more heat is lost from the evaporation of water in sweat) and lowering of body hair by elation of erector pill muscles (so less air is trapped, therefore less insulation and heat is lost more easily).
This negative feedback mechanism is important because temperature can increase the kinetic energy of molecules, meaning that hydrogen bonds holding the enzyme together can break. The active site of the enzyme therefore changes and no E-S complexes can be formed. Negative feedback is also seen in the control of blood glucose concentration. The blood glucose concentration is monitored by the cells in the pancreas. The islets of Lanterns contain alpha cells which secrete clangor into the blood and they also contain beta cells which secrete insulin into the blood.
If the blood glucose concentration is too high, the water potential of the blood is reduced so low that water leaves cells by osmosis into the blood which can cause cells to shrivel and die. Insulin is a hormone secreted by beta cells to reduce blood glucose concentration. It does this by binding to specific receptors on cell membranes of liver cells and muscle cells, increasing the permeability of cell membranes to glucose, so more glucose is taken up.
Insulin also activates enzymes for glycogen’s. Insulin also increases the rate of respiration of glucose. Conversely, when the blood glucose concentration is too low, clangor is secreted which promotes glutinousness and selenologists. Therefore increasing the glucose concentration in blood and returning it to the norm. In conclusion, negative feedback is very important for homeostasis and is a major mechanism that controls our internal environment.