countercurrent multiplier

countercurrent multiplier: A system in which energy is used to transport material across a membrane separating two c. tubes connected at one end to form a hairpin shape; by this means a concentration can be achieved in the fluid in the hairpin bend, relative to the inflow and outflow fluids, that is much greater than the transport mechanism could produce between the two sides of the membrane at any point; e.g., the nephronic loops in the renal medulla act as countercurrent multiplier s.

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Countercurrent exchange — Counter heat current exchange: Note the gradually declining differential and that the once hot and cold streams exit at the reversed temperature difference; the hotter entering stream becomes the exiting cooler stream and vice versa.… … Wikipedia
Countercurrent multiplication — A countercurrent multiplier system is a mechanism that expends energy to create a concentration gradient. It is found widely in nature and especially in mamalian organs. For example, it can refer to the process underlying the process of urine… … Wikipedia
Loop of Henle — Scheme of renal tubule and its vascular supply. (Loop of Henle visible center left.) Latin ansa nephroni Gray s … Wikipedia
Nephron — For the drug with trade name Nephron, see Epinephrine. Nephron Nephron of the kidney without juxtaglomerular apparatus Latin nephroneum Gray s … Wikipedia
mechanism — 1. An arrangement or grouping of the parts of anything that has a definite action. 2. The means by which an effect is obtained. 3. The chain of events in a particular process. 4. The detailed description of a reaction pathway. [G. mechane, a… … Medical dictionary
renal system — ▪ anatomy Introduction in humans (human body), organ system that includes the kidneys, where urine is produced, and the ureters, bladder, and urethra for the passage, storage, and voiding of urine. In many respects the human excretory, or… … Universalium

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