Medical-dictionary.cc

What does the word kidney mean?

• One of the two organs which excrete the urine. The kidneys are bean- shaped organs, about 4 1/ 2 in. in length, 2 in. in width, and 1 1/ 4 in. in thickness, lying on either side of the spinal column, behind the peritoneum, about opposite the twelfth thoracic and first three lumbar vertebrae. At the inner edge of each kidney is a concave depression, the hylus, where the vessels and nerves enter and leave the organs and where the ureter emerges; the hylus leads into the renal sinus, a hollow containing the pelvis and calyces and the branching blood- vessels. The kidney is enclosed in a fibrous envelope, the capsule, which dips into the sinus at the hilus. The substance of the organ is divided into cortex and medulla; the former is darker colored and more granular in appearance than the latter; it contains the Malpighian corpuscles and most of the convoluted tubules; the medulla is lighter in color and striated and contains the majority of the straight tubules; it is formed of the pyramids whose bases rest in the cortex and whose apices are the renal papillae at which point the central collecting tubule opens into a calyx, this in turn emptying into the pelvis of the kidney from which the water passes into the ureter and so reaches the urinary bladder. The pyramids are made up of tubules; each tubule begins at the glomerulus, or Malpighian corpuscle, in the cortex; it is first convoluted, then enters the pyramid, passing down toward the papilla, near which it turns back on itself, the turn being called Henle's loop, it then ascends to the cortex, where it is again convoluted ( being called the irregular tubule), and returns to the pyramid in the center of which it empties into the straight collecting tube, which terminates, usually after uniting with others, at the apex of the papilla. Projections of masses of tubules pass up into the cortex, being known as medullary rays, while the cortical substance often passes down between the pyramids, forming the so- called columns of Berlin; the cortical substance between the medullary rays is also called the labyrinth.

• The kidneys or reins are the secretory organs of the urine. They are two glands, situate deeply, - the one on the right, and the other on the left side- in the hypochondres: at the sides of the lumbar vertebrae; behind the peritoneum; and in the midst of an abundant, fatty areolar tissue. The kidney is of a reddish-brown colour; oval form; and flattened on two surfaces. It has, at its internal margin, a deep fissure, by which the renal vessels and nerves enter or quit the organ, and the ureter issues. It resembles, pretty accurately, the haricot or kidney-bean. Two substances are readily distinguishable in it; - the outer, secerning, cortical, glandular or vascular, which secretes the urine; and the inner, tubular, medullary, uriniferous, conoidal or radiated, which appears under the form of small cones or unequal papillae or mammillae, each resulting from the union of small capillary tubes, adherent by one of their extremities to the cortical substance; and opening, by the other, at the summit of the cone, into calices, a species of membranous tubes, more or less numerous, which transmit the urine of the papillae to the pelvis. By the pelvis is meant a small, membranous sac, of an irregularly oval shape, at the base of which are the orifices of the calices, and the other extremity of which is continuous with the ureter. The kidney is surrounded by a fibrous membrane proper to it, Perineph’rus. It has been shown by Mr. Bowman and others that the renal artery is distributed to the corpora Malpighiana, forming a pellet of convolutions, which is received into a flask-like dilatation of the ureter- Bowman's Capsule, and through which- it is conceived- the watery portion of the urine is separated. The blood then becomes venous, and is distributed by different veins- portal veins of the kidney- to the convoluted tubes through which the proper urine is secreted. Hence the blood passes into the renal vein. The intermediate vessels between the Malpighian bodies and the convoluted tubes have been termed the Portal System of the Kidney.

• One of the pair of organs secreting the urine. It is bean-shaped, the concave border having a notch( hilum) opening into a cavity( sinus), into which pass the ureter, vessels, and nerves for the k. The ureter in hilum expands into a funnel-shaped reservoir( pelvis) which divides into 7 to 13 pockets( calices). Into these project the apices( papillae) of 8 to 18 diverging striated pyramidal masses( phyramids of Malpighi) which together constitute the medulla of the k. Lining the bases of the pyramids is the granular cortex of the k., which dips down between the pyramids forming the columns of Bertin. Investing the cortex is a fibrous, readily separable membrane( capsule of k.). The uriniferous tubules begin in the cortex as spherical expansions( Malpighian capsules); leaving this, they run first as a coil( convoluted tubule), then as a spiral( spiral tubule), in the cortex; then dip down into the medulla and return to the cortex, forming the descending and ascending branches of the loop of Henle; then in the cortex run first in zigzags( zigzag or irregular tubule), next in coils( secondary convoluted tubule), and finally enter the medulla again, where they run in a straight course, forming the straight or collecting tubules, which, by repeated junctions with other tubules, form the discharging tubules, opening upon the papillae in the calices. The straight tubules, where they lie outside of the pyramids of Malpighi, form bundles radiating from the base of the latter toward the capsule( pyramids of Ferrein, medullary rays). The urinary tubules and Malpighian capsule consist of a continuous basement membrane lined with epithelium which is flattened in the capsule, cuboidal in the tubes. The arteries of the k. run between the pyramids to the base of the latter, where they form arches which send branches down to the pyramids( arteriae rectae) and up to the cortex( interlobular or radiate arteries). The latter in part break up into capillaries surrounding the uriniferous tubules, partly supply each Malpighian capsule with an afferent vessel, which invaginates the wall of the capsule, forming a pouch in which it breaks up into a coil of capillaries( the Malpighian tuft). These latter reunite to form the efferent vessel, and this, on leaving the Malpighian capsule, breaks up into a second set of capillaries which surround the uriniferous tubules. The function of the k., performed partly by the Malpighian capsules and partly by the secreting cells of the uriniferous tubules, is to separate from the blood water, urea, and other constituents of the urine, some of which, such as hippuric acid, are probably manufactured by it. Cardiack., Hepatic k., disease of the k. due to insufficiency of the heart or liver. Contracted k. ( Atrophic k., Granular k., Gouty k.), Large white k. ( Branny k.), Surgical k., see Nephritis,. Head k., the pronephros. Primordial k., the pronephros and Wolffian body.

Each person working in the medical industry sometimes needs to know how to define a word from medical terminology. For example - how to explain kidney? Here you can see the medical definition for kidney. Medical-dictionary.cc is your online dictionary, full of medical definitions.