Kidney

[kid’-ne) [ME., kidnere, from Icel., kvitir, the womb; nyra, kidney]. One of the two large glandular organs situated in the upper and posterior portion of the abdominal cavity, and concerned in the excretion of the urine. It consists of an outer cortical substance, and an inner medullary substance. The medulla consists of from 8 to 1 8 pyramids (pyramids of Malpighi), the apices of which, the papillae, project into the calices of the ureter. The pyramids are striated, and in places send narrow projections into the cortex, the medullary rays, or pyramids of Ferrein. Between the pyramids are extensions from the cortex, the columns of Bertini. The cortex, by the penetration into it of the medullary rays, is divided into medullary rays and the labyrinth. The secreting structure of the kidney consists of long tubes,beginning in an expanded extremity, the capsule of Bowman, which invests a tuft of blood-ve els, the glomerulus, and constitutes, together with this, a Malpighian body; extending from this is the proximal convoluted tubule; then comes the spiral tubule, then the loop of Henle, consisting of a descending and an ascending limb; then the distal convoluted tubule, which terminates in the collecting tubule. The blood-ve els of the kidney divide into two sets of branches, one supplying the cortex, the other the medulla. The kidney weighs about 150 grams. K., Amyloid, a kidney the seat of amyloid degeneration. K., Fatty, one the seat of extensive fatty degeneration. K., Floating, one susceptible of displacement over a considerable extent of the abdomen, a condition most frequent in women, and as a rule affecting the right side. K., Gouty, or K., Granular, the small kidney resulting from chronic interstitial nephritis. K., Horseshoe. See Horseshoe-kidney. K., Large White, that of the advanced stage of chronic parenchymatous nephritis. K. of Pregnancy, an anemic kidney with fatty infiltration of the epithelial cells, but without any acute or chronic inflammation, occurring in pregnant women. K., Pigback, the large congested kidney found in alcoholic subjects. K., Red Contracted. See K, Granular. K., Small White, the final stage of the large white kidney after lo of its substance from atrophy or degeneration. K., Surgical, pyelonephritis. K., Waxy. Same as Z[, Amyloid. 349