kidney


kidney
kidneylike, adj.
/kid"nee/, n., pl. kidneys.
1. Anat. either of a pair of bean-shaped organs in the back part of the abdominal cavity that form and excrete urine, regulate fluid and electrolyte balance, and act as endocrine glands.
2. Zool. a corresponding organ in other vertebrate animals or an organ of like function in invertebrates.
3. the meat of an animal's kidney used as food.
4. constitution or temperament: He was a quiet child, of a different kidney from his boisterous brothers.
5. kind, sort, or class: He is only at ease with men of his own kidney.
[1275-1325; ME kidenei, kidenere (sing.), kideneres, kideneren (pl.); orig. uncert.; perh. a compound based either on nere (sing.), neres (pl.) kidney (OE *neore; cf. OHG nioro, ON nyra); or ei (sing.), eiren (pl.) EGG1, OE aeg (sing.), aegru (pl.) (by assoc. with the organ's shape); for the first element cf. dial. kid pod (akin to COD2)]

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I
One of a pair of organs that maintain water balance and expel metabolic wastes.

Human kidneys are bean-shaped organs about 4 in. (10 cm) long, in the small of the back. They filter the entire 5-quart (about 4.5-liter) water content of the blood every 45 minutes. Glucose, minerals, and needed water are returned to the blood by reabsorption. The remaining fluid and wastes pass into collecting ducts, flowing to the ureter and bladder as urine. Each kidney has over 1 million functional units (nephrons) involved in the process of filtration and reabsorption. The kidneys also secrete renin, an enzyme involved in blood pressure regulation. Disorders include kidney failure, kidney stones, and nephritis. See also urinary system.
II
(as used in expressions)

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 in vertebrates and some invertebrates, organ that maintains water balance and expels metabolic wastes. Primitive and embryonic kidneys consist of two series of specialized tubules that empty into two collecting ducts, the Wolffian ducts (Wolffian duct) (see Wolffian duct). The more advanced kidney (metanephros) of adult reptiles, birds, and mammals is a paired compact organ whose functional units, called nephrons (nephron), filter initial urine from the blood, reabsorb water and nutrients, and secrete wastes, producing the final urine, which is expelled.

      Reptilian and avian kidneys are made up of many tiny lobules that, in birds, are combined into three or more lobes. Collecting tubules from each lobule empty into a separate branch of the ureter. Reptiles have relatively few nephrons (from 3,000 to 30,000 in lizards), while birds have a great number (around 200,000 in a fowl, twice as many as in a mammal of comparable size).

      Mammalian kidneys have a somewhat granular outer section (the cortex), containing the glomeruli and convoluted tubules, and a smooth, somewhat striated inner section (the medulla), containing the loops of Henle and the collecting tubules. As the ureter enters the kidney it enlarges into a cavity, the renal pelvis; (renal pelvis) urine passes into this pelvis from the collecting tubules. Nephrons are numerous (20,000 in a mouse).

 In humans the kidneys are about 10 centimetres long and are located beneath the diaphragm and behind the peritoneum. Each kidney contains 1,000,000–1,250,000 nephrons that filter the entire five-quart water content of the blood every 45 minutes—an equivalent of 160 quarts a day. Of this, only 1 1/2 quarts are excreted; the remainder is reabsorbed by the nephrons.

      Damaged kidneys secrete an enzyme called renin that stimulates constriction of the blood vessels. When the damage has been caused initially by high blood pressure, the increase in pressure from the constricted vessels causes more kidney damage.

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Universalium. 2010.

Look at other dictionaries:

  • Kidney — Kid ney (k[i^]d n[y^]), n.; pl. {Kidneys} (k[i^]d n[i^]z). [OE. kidnei, kidnere, from Icel. koi[eth]r belly, womb (akin to Goth. gipus, AS. cwi[thorn] womb) + OE. nere kidney; akin to D. nier, G. niere, OHG. nioro, Icel. n[=y]ra, Dan. nyre, Sw.… …   The Collaborative International Dictionary of English

  • kidney — (n.) early 14c., of unknown origin, originally kidenere, perhaps a compound of O.E. cwið womb (see BOWEL (Cf. bowel)) + ey egg (see EGG (Cf. egg) (n.)) in reference to the shape of the organ. Figurative sense of temperament is from 1550s. Kidney… …   Etymology dictionary

  • kidney — ► NOUN (pl. kidneys) 1) each of a pair of organs in the abdominal cavity, with one concave and one convex side, that excrete urine. 2) the kidney of a sheep, ox, or pig as food. 3) archaic nature or temperament. ORIGIN of obscure origin …   English terms dictionary

  • kidney — [kid′nē] n. pl. kidneys [ME kidenei < ?] 1. either of a pair of glandular organs in the upper abdominal cavity of vertebrates, which separate water and waste products of metabolism from the blood and excrete them as urine through the bladder 2 …   English World dictionary

  • kidney — kind, sort, *type, nature, description, character, stripe, ilk …   New Dictionary of Synonyms

  • kidney — has the plural form kidneys …   Modern English usage

  • Kidney — For other uses, see Kidney (disambiguation). Kidney Human kidneys viewed from behind with spine removed Latin ren Artery …   Wikipedia

  • Kidney — One of a pair of organs located in the right and left side of the abdomen which clear "poisons" from the blood, regulate acid concentration and maintain water balance in the body by excreting urine. The kidneys are part of the urinary… …   Medical dictionary

  • kidney — n. (pl. eys) 1 either of a pair of organs in the abdominal cavity of mammals, birds, and reptiles, which remove nitrogenous wastes from the blood and excrete urine. 2 the kidney of a sheep, ox, or pig as food. 3 temperament, nature, kind (a man… …   Useful english dictionary

  • kidney */ — UK [ˈkɪdnɪ] / US noun Word forms kidney : singular kidney plural kidneys 1) [countable] one of the two organs in your body that clean your blood and remove waste They had to remove his kidney. kidney failure/disease a kidney transplant 2)… …   English dictionary


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