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DISCUSS THE CONCEPT OF HOMEOSTASIS PARTICULARLY IN RELATION TO TEMPERATURE CONTROL In complex organisms organs are united to form organ systems such as the digestive, reproductive, nervous and muscular systems. The fact that all of the organ systems generally work in a highly coordinated manner suggests strongly that organisms possess distinct physiological control mechanisms that make the coordination of such highly complex processes possible. One of the most interesting features of such control mechanisms is that they are built into the system to regulate it. The controls are self-adjusting and do not require constant monitoring from an outside agent. Such controls maintain the system in equilibrium. Maintaining a constant internal environment is a struggle which of course is one that every physiological system ultimately loses; death being the final failure of the bodies system. By internal environment we mean the immediate vacinity of the cells, mammalian tissue cells are surrounded by tiny channels and spaces filled with fluid, these provide the cells with the medium in which they have to live and this represents the organs internal environment. It must be kept constant if the cells are to continue their vital functions. ...read more.


There are two types of feedback mechanisms, negative and positive. The control of body processes often occurs through the operation of negative feedback; movement away from an ideal state causes a return back to the ideal state, or "set point". One example of this is sweating, when a change in the system in one direction (sweating) is converted into a command to change that system in another direction (reduce sweating). In body temperature control, increased sweating lowers the body temperature, a decrease in the body temperature is converted to a command to decrease the amount of water excreted through the sweat glands. This contributes to a rise in body temperature and thus increases sweating. Using such control mechanisms the body acts to counteract disturbances in order to restore homeostasis. Positive feedback however may destroy the equilibrium. It may occur when the normal control mechanism in the body breaks down. If body temperature rises much above 42 c the negative feedback mechanism breaks down and is replaced by positive feedback. The high temperature brings about an increase in the metabolic rate; this produces more heat, which raises the temperature, and so on. The ultimate result if left unchecked is death. ...read more.


The body secretes the hormone adrenaline, which raises the metabolic rate and therefore increases heat production. If the environment is hotter than blood temperature there are also four physiological responses that occur, sweating, vasodilation, a decrease in metabolism and the lowering of hairs by relaxation of the erector pili muscles. The responses involve the reverse of those concerned with cold conditions. The arterioles which lead to the skin capillaries dilate which causes the blood flow to the surface of the skin to be increased, this means that more heat energy is lost to the environment, this is known as vasodilation. The hypothalamus stimulates the production of sweat which is a watery fluid secreted from the sweat glands in the skin. The evaporation of the sweat cools the skin and the blood perfusing through it. As cooler blood flows back to the central regions of the body some passes through the hypothalamus and conveys a message to it that the blood temperature has decreased. The hypothalamus responds by reducing its stimulation of the sweat glands. As a means of dissipating heat sweating is extremely important, there is no other means of getting rid of excess heat. As we can see from the above information temperature control through homeostasis is an essential function, without which our bodies and other living organisms would not be able to survive. ...read more.

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