nephron
/nef"ron/, n. Anat., Zool.
the filtering and excretory unit of the kidney, consisting of the glomerulus and tubules.
[1930-35; < G; alter. of Gk nephrós kidney]

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Functional unit of the kidney that removes waste and excess substances from the blood to produce urine.

Each of the million or so nephrons in each kidney is a tubule 1.2–2.2 in. (30–55 mm) long. At one end it is closed, expanded, and folded into a double-walled cuplike structure (Bowman's capsule) enclosing a cluster of capillaries (glomerulus). Fluid forced out of the blood through the capillary walls of the glomerulus into Bowman's capsule flows into the adjacent renal tubule, where water and nutrients are selectively reabsorbed from the fluid back into the blood, and electrolytes such as sodium and potassium are balanced in several distinct sections along its length. The final concentrated product is urine. See also urinary system.

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 functional unit of the kidney, the structure that actually produces urine in the process of removing waste and excess substances from the blood. There are about 1,000,000 nephrons in each human kidney. The most primitive nephrons are found in the kidneys ( pronephros) of primitive fish, amphibian larvae, and embryos of more advanced vertebrates. The nephrons found in the kidneys ( mesonephros) of amphibians and most fish, and in the late embryonic development of more advanced vertebrates, are only slightly more advanced in structure. The most advanced nephrons occur in the adult kidneys, or metanephros, of land vertebrates, such as reptiles, birds, and mammals.

      Each nephron in the mammalian kidney is a long tubule, or extremely fine tube, about 30–55 mm (1.2–2.2 inches) long. At one end this tube is closed, expanded, and folded into a double-walled cuplike structure. This structure, called the renal corpuscular capsule, or Bowman's capsule, encloses a cluster of microscopic blood vessels—capillaries—called the glomerulus. The capsule and glomerulus together constitute the renal corpuscle. Blood flows into and away from the glomerulus through tiny arteries called arterioles, which reach and leave the glomerulus through the open end of the capsule. In the renal corpuscle, fluid filters out of the blood in the glomerulus through the inner wall of the capsule and into the nephron tubule. As this filtrate passes through the tubule, its composition is altered by the secretion of certain substances into it and by the selective reabsorption of water and other constituents from it. The final product is urine, which is conveyed through the collecting tubules into the renal pelvis.

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Universalium. 2010.

Look at other dictionaries:

  • néphron — [ nefrɔ̃ ] n. m. • 1954; du gr. nephros ♦ Physiol., anat. Unité anatomique et fonctionnelle du rein, constituée par un glomérule rénal et les tubes rénaux qui s y rattachent. Un rein humain comprend environ 1 million de néphrons. ● néphron nom… …   Encyclopédie Universelle

  • Nephron — Nephron, als blind geschlossenes Rohr aus dem ⇒ Malpighi Körperchen und dem sich anschließenden ⇒ Nierenkanälchen zusammengesetzte anatomische und funktionelle Einheit der ⇒ Niere der Wirbeltiere. Im N. erfolgt die Bildung des ⇒ Harns. ⊙ Nephron… …   Deutsch wörterbuch der biologie

  • nephron — (n.) 1932, from Ger. nephron (1924), from Gk. nephros kidney, from PIE *negwhro kidney (Cf. L. nefrones, O.N. nyra, Du. nier, Ger. Niere kidney ) …   Etymology dictionary

  • nephron — [nef′rän΄, nef′rən] n. [Ger < Gr nephros: see NEPHRO ] a single urinary tubule in the vertebrate kidney …   English World dictionary

  • Nephron — For the drug with trade name Nephron, see Epinephrine. Nephron Nephron of the kidney without juxtaglomerular apparatus Latin nephroneum Gray s …   Wikipedia

  • Néphron — Le néphron est l unité structurale et fonctionnelle du rein. Il permet la formation d urine. Un rein humain adulte en compte entre 900 000 et 1,6 million. Sommaire 1 Embryologie 2 Structure 2.1 Le glomérule …   Wikipédia en Français

  • Nephron — Ein Nephron (von griech. νεφρός Niere) ist die funktionelle Untereinheit der Niere. Es besteht aus: dem Nierenkörperchen (Malpighi Körperchen, benannt nach Marcello Malpighi) und dem daran angeschlossenen Nierenkanälchen (Tubulus). Jede Niere… …   Deutsch Wikipedia

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