loop
 [lo̳p] a turn or sharp curve in a cordlike structure.
capillary l's minute endothelial tubes that carry blood in the papillae of the skin.
closed loop a system in which the input to one or more of the subsystems is affected by its own output.
Henle's loop the U-shaped part of the 
nephron extending from the proximal to the distal convoluted tubule.
 Lippes loop a form of intrauterine contraceptive device.
open loop a system in which an input alters the output, but the output has no effect on the input.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.