Examples Of Negative Feedback
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 myogenic, meaning that each heartbeat is initiated by sinoatrial 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. Chemoreceptors in the carotid arteries and aortic walls detect this change in pH. They increase the frequency of nerve impulses to the centre in the medulla oblongata. The centre increases the frequency of impulses via the sympathetic nervous …show more content…
Changes in body temperature are detected by thermoreceptors. The hypothalamus has receptors which detect internal temperature. These thermoreceptors send nerve impulses to a heat loss or gain centre in the hypothalamus which in turn sends impulses to the effector. For example, if the environment surrounding an endotherm is very hot. This high temperature will be detected by thermoreceptors 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 effector to produce an appropriate response such as vasodilation (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 relaxation of erector pili 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
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 myogenic, meaning that each heartbeat is initiated by sinoatrial 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. Chemoreceptors in the carotid arteries and aortic walls detect this change in pH. They increase the frequency of nerve impulses to the centre in the medulla oblongata. The centre increases the frequency of impulses via the sympathetic nervous …show more content…
Changes in body temperature are detected by thermoreceptors. The hypothalamus has receptors which detect internal temperature. These thermoreceptors send nerve impulses to a heat loss or gain centre in the hypothalamus which in turn sends impulses to the effector. For example, if the environment surrounding an endotherm is very hot. This high temperature will be detected by thermoreceptors 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 effector to produce an appropriate response such as vasodilation (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 relaxation of erector pili 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