Respiratory System Essay

9198 Words Aug 12th, 2013 37 Pages
respiratory system, the system in living organisms that takes up oxygen and discharges carbon dioxide in order to satisfy energy requirements. In the living organism, energy is liberated, along with carbon dioxide, through the oxidation of molecules containing carbon. The termrespiration denotes the exchange of the respiratory gases (oxygen and carbon dioxide) between the organism and the medium in which it lives and between the cells of the body and the tissue fluid that bathes them.

With the exception of energy used by animal life in the deep ocean, all energy used by animals is ultimately derived from the energy of sunlight. The carbon dioxide in the atmosphere in conjunction with the energy of sunlight is used by plants to
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Thus, fishmay expend about 20 percent of their total oxygen consumption in running the respiratory pump, as compared with about 1 to 2 percent in mammals, including humans.

The carbon dioxide content of most natural waters is low compared with air, often almost nil. In contrast to oxygen, carbon dioxide is extremely soluble in water and diffuses rapidly. Most of the carbon dioxide entering water combines either with the water (to form carbonic acid) or with other substances (to form carbonates or bicarbonates). This buffering capacity maintains a low level of free carbon dioxide and facilitates the maintenance of a favourable diffusion gradient for carbon dioxide exchange by water breathers. In general, oxygen exchange, which is strongly dependent on the oxygen content of the water, is more critically limiting for aquatic forms than is the exchange of carbon dioxide.

Temperature exerts a profound effect on the solubility of gases in water. A change from 5° to 35° C (41° to 95° F) reduces the oxygen content of fresh water by nearly half. At the same time, a rise in body temperature produces an increase in oxygen consumption among animals that do not closely regulate their body temperatures (so-called cold-blooded animals). A fish experiencing both rising water and body temperatures is under a double handicap: more water must

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