Describe the structure and functioning of nephrons.

Structure of Nephron: Nephron is the functional  unit of kidney. It consists of a tubule which is connected with collecting duct at one end and a cup shaped structure at the other end. This cup-shaped structure is called Bowman’s capsule. Every Bowman’s capsule contains a cluster of capillaries, called Glomerulus, within the cup-shaped structure. The blood enters into glomerulus through afferent arteriole of renal artery and leaves it through efferent arteriole.

Fig. Structure of nephron

Functioning of nephron:
Filtration of blood takes in Bowman’s capsule from the capillaries of glomerulus. The filterate passes into the tubular part of the nephron. This filterate contains glucose, amino acids, urea, uric acid, salts and a major amount of water. Reabsorption: As the filterate flows along the tubule useful substances such as glucose, amino acids, salts and water are selectively reabsorbed into the blood by capillaries surrounding the nephron tubule. The amount of water reabsorbed depends on the need of the body and also on the amount of wastes to be excreted. The filterate which remained after reabsorption is called urine. Urine contain dissolved nitrogenous waste i.e., urea and uric acid, excess salts and water. Urine is collected from nephrons by the collecting dust to carry it to the ureter.