homeostasis

homeostasis - 1 www.ecosystema.ru/eng/ 2 The term...

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The term ‘homeostasis’ is derived from two Greek words; Homeo which means ‘unchanging’ and Stasis which means ‘standing’ In its simplest form it means ‘staying the same’ It is an organism’s internal environment which ‘stays the same’ The ‘internal environment’ refers to the conditions inside an organism. These conditions remain more or less constant despite changes such as pH or temperature in the outside environment In practice, it comes down to providing a stable environment for the cells of the body 2
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The living processes in the cells depend on the activity of enzymes . ( See ‘Chemicals of living cells’ www.biology- resources.com/biology-CD.html) These enzymes work best in specific conditions such as those of temperature and pH. Any change in these conditions affects the function of the enzymes and may lead to the death of the cells or, ultimately, the whole organism This is why the internal environment needs to be regulated and kept constant. In fact, the internal conditions are not absolutely constant, but allowed to vary within very narrow limits. Human body temperature, for example, varies between 36.1 – 37.8 o C. The average temperature is usually expressed as 36.8 o C 3
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To avoid making exceptions and qualifications, we will consider homeostasis as it applies to the human body There is no specific organ which controls homeostasis except, possibly, the brain The skin, kidneys, liver, endocrine system, nervous system and sensory system all play a part in maintaining the internal environment within narrow limits The skin is a homeostatic organ which helps maintain the body temperature within the limits given in the previous slide
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homeostasis - 1 www.ecosystema.ru/eng/ 2 The term...

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