67. Intext question XIX

 

The kidney is composed of filtering units called a nephronneuron. A single kidney contains about \(ten lakh\) nephrons. Nephrons are the structural and functional units of the kidneys. Blood enters the kidney from the aorta through the renal arteryrenal vein. It is distributed as smaller vessels until it forms a cluster of thin-walled capillaries in each of the nephrons. Then, the renal artery divides further, forming the afferent renal arterioles. The afferent renal arteriole enters the nephron through Renal pelvisBowman's capsule.

 

The nephron is composed of a cup-shaped Bowman's capsule. The afferent renal arteriole forms a network of blood capillaries in the Bowman's capsule to form the glomerulus. The glomerulus and the Bowman's capsule together form the medullarenal corpuscle. The blood entering the glomerulus carries wastes that are filtered in the Bowman's capsule. Efferent renal arteriole takes the blood and leaves from the glomerulus.

 

The Bowman's capsule extends further as a long tube that is highly coiled, called the proximal convoluted tubule distal convoluted tubule . Then it goes downwards and again upwards as a U-shaped loop called the glomerulusloop of Henle. The loop of Henle become coiled as a distal convoluted tubuleproximal convoluted tubule that reaches and joins the collecting duct. Tubes from different nephrons converge into the collecting duct, which finally goes to the ureter.