Images Dated 10th February 2003

Illustration of nephron structure in human kidney

Illustration of a nephron, the functional unit of excretion in the human kidney. As a blood filtering system, a nephron is richly supplied with capillaries from branches of the renal artery (red) and vein (blue). At centre right, a knot of capillaries (the glomerulus) is surrounded by Bowman's capsule (blue). It is here that excretory products are filtered from the blood, and pass into a convoluted tubule (yellow). Urine is con- centrated in this tubule, particularly in the thin loop of Henle (at bottom) with useful products re- absorbed into the blood. A collecting duct (left) passes this urine to the ureter, then bladder

© FRANCIS LEROY, BIOCOSMOS/SCIENCE PHOTO LIBRARY