51. The kidney's function

The kidneys are filters which remove waste products from the blood. In the human each is a bean—shaped organ, some four inches long and about two inches wide. The two are situated high up on the posterior abdominal wall behind the peritoneum and in front of the lats ribs and the upper two lunbar transverse processes. Each is invested by a fibrous capsule surrounded by more or less peri—nephric fat. On the upper pole of each is a supra—renal gland. On the medical side is a notch called the hilum where the vessels and the ureter are attached.

Vertical selections through a kidney discloses three more or less concentric zones. The other light—colored zone is the renal cortex, within this is the darker renal medulla and within this again is a space – the renal sinus which is normally occurred by a fibrous bag called the renal pelvis. The pelvis opens below into the ureter. The cortex extends inwards in a series of renal columns which divide the medulla into a number of renal pyramids. Each pyramid has a free rounded projection – a renal papilla – which lies in a cap – like extension, of the pelvis cal led a renal calyx. The pelvis is lined by transitioual epithelium, which extends the calyces and covers the papillae.

Within the cortex each minute artery presents along its course a convoluted knot, called a glomerulus; the branch which enters the knot is the afferent vessel, that which leaves is she efferent vessel. Each glomerulus project into the dilated end of its corresponding renal tubule, from which it is separated by a thin layer of cells called glome—rular (Bowman' s) capsule; glomerulus plus capsule form a renal (Nalpighian) corpuscle. The cortex contains multitudes of such corpuscles, each giving rise to a tubule which passes down into the medul la and back again in the so—called loop of Henle. Back in, the cortex loop ends in a functional tubule which joins а larger collecting tube. Ultimately, a number of collecting tubes combine to form an excretory tube, which opens at the ареx of a papilla into a renal calyx. The efferent vessel from the glomerulus accompanies the loop of Henle, supply ing the tubule on the way and finally ends in a small vein. A renal corpuscule plus its complement of tubules and blood vessels is called a renal unit, or nephron; there are said to be one million such units in each kidney, their tubing totaling a length of some twenty miles.

New words

bean—shaped organ – орган в форме боба

four inches long – 4 дюйма в длину

two inches wide – 2 дюйма в ширину

peritoneum – брюшина

lumbar – поясничный

renal cortex – корковый слой

renal medulla – мозговой слой

fibrous – волокнистая

dilated – расширенный

to be separated – быть разделенным

loop of henle – петля Генле

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