Excretion is the process of eliminating waste products of metabolism and other materials that are of no use. It is an essential process in all forms of life. In one-celled organisms wastes are discharged through the surface of the cell. The higher plants eliminate gases through the stomata, or pores, on the leaf surface. They also have been shown (by British biologist Brian J. Ford) to translocate wastes into leaves which are then shed. In this fashion, the leaf, in addition to acting as an energy-trapping structure, is also a plant's organ of excretion.
Multicellular animals have special excretory organs. In humans the main organs of excretion are the kidneys and accessory urinary organs, through which urine is eliminated (see urinary system), and the large intestines, from which solid wastes are expelled. The skin and lungs also have excretory functions: The skin eliminates water and salt in sweat, and the lungs expel water vapor and carbon dioxide." [1]
In mammals, for example, the two major excretory processes are the formation of urine in the kidneys and the formation of carbon dioxide (a human's most abundant metabolic waste) molecules as a result of respiration, which is then exhaled from the lungs.
The waste products are eliminated by urination and exhalation respectively. In urination, Hormone control over excretion occurs in the distal tubules of the kidneys as directed by the hypothalamus.
Perspiration is another excretory process which removes salts and water, although the primary purpose is cooling.
In insects, a system involving Malpighian tubules is utilized to excrete metabolic waste. Metabolic waste diffuses or is actively transported into the tubule, which transports the wastes to the intestines. The metabolic waste is then released from the body along with fecal stuffs.
Many people misuse the term excretion as a sort of euphemism for defecation, and use excrement for feces, but this is medically improper.
2006-12-26 10:33:58
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answer #1
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answered by Apollo 4
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Excretion Definition
2016-10-02 00:43:32
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answer #2
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answered by Erika 4
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Removal of waste from the body is called excretion. It may be in the form of gas, liquid and solid. The organs of excretion are: Skin subserves the function of excretion as the sweat gland(sudorifc gland) excretes salt and urea in the form of perspiration. Lungs help in the removal of carbon dioxide. Liver, among other functions, destroys old RBC and degrades the protopohyrin of the heme to produce bile pigments which are released in the duodenum to be passed out through the feces. Kidney filters the blood and removes urea, salt, water etc. Large intestine absorbs water and leaves behind the solid waste of digested food as fecal matter.
2016-03-17 22:29:14
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answer #3
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answered by Anonymous
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Removal of nitrogenous waste from the body in order to maintain equalibrium between solid and fluid contents is called excretion.
2006-12-26 11:59:46
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answer #4
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answered by moosa 5
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Excretion = To excrete, to send out.
2006-12-26 11:17:44
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answer #5
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answered by lemon drops 3
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1
2017-02-09 11:54:29
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answer #6
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answered by Bradley 4
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Excretion basically means relaesing our waste from our body through our skin, anus, and bladder.
2006-12-27 06:47:18
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answer #7
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answered by jjefferson210 2
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the act or state of excreting:
the substance excreted, as urine or sweat, or certain plant products.
2006-12-26 10:35:39
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answer #8
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answered by SG 2
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The process of releasing waste material through the rectum found in the human body.
2006-12-26 11:44:47
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answer #9
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answered by leged56 5
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the substance excreted, as urine or sweat, or certain plant products
2006-12-26 10:33:10
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answer #10
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answered by rhino_man420 6
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