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Homeostasis - life must perform(recall the discussion in...

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Homeostasis is the maintenance of a stable internal environment. Homeostasis is a term coined in 1959 to describe the physical and chemical parameters that an organism must maintain to allow proper functioning of its component cells, tissues, organs, and organ systems. Recall that enzymes function best when within a certain range of temperature and pH, and that cells must strive to maintain a balance between having too much or too little water in relation to their external environment. Both situations demonstrate homeostasis. Just as we have a certain temperature range (or comfort zone), so our body has a range of environmental (internal as well as external) parameters within which it works best. Multicellular organisms accomplish this by having organs and organ systems that coordinate their homeostasis. In addition to the other functions that
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Unformatted text preview: life must perform (recall the discussion in our Introduction chapter), unicellular creatures must accomplish their homeostasis within but a single cell! Single-celled organisms are surrounded by their external environment. They move materials into and out of the cell by regulation of the cell membrane and its functioning. Most multicellular organisms have most of their cells protected from the external environment, having them surrounded by an aqueous internal environment. This internal environment must be maintained in such a state as to allow maximum efficiency. The ultimate control of homeostasis is done by the nervous system. Often this control is in the form of negative feedback loops. Heat control is a major function of homeostatic conditions that involves the integration of skin, muscular, nervous, and circulatory systems....
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