Name the part of the human excretory system where nephrons are found. Write the structure and function of nephrons.

Location of Nephrons

Nephrons are the basic structural and functional filtration units found inside the kidneys of the human excretory system.

Structure of a Nephron

Each nephron consists of two main parts:

1. Bowman's Capsule: A cup-shaped, double-walled bag at the upper end of the nephron.
2. Glomerulus: A dense network of thin-walled blood capillaries enclosed within the Bowman's capsule, connected to the renal artery.
3. Tubular Part: A long, highly coiled tube (comprising proximal and distal tubules and the loop of Henle) surrounded by a network of blood capillaries. It eventually opens into a collecting duct.

Function of a Nephron

1. Ultrafiltration: Blood flows through the glomerulus under high pressure. Water and small dissolved solutes (like glucose, amino acids, salts, and urea) are filtered out into the Bowman's capsule as the initial filtrate.
2. Selective Reabsorption: As this filtrate flows along the tubular part, useful substances such as glucose, amino acids, salts, and a major amount of water are selectively reabsorbed back into the surrounding blood capillaries.
3. Urine Formation and Excretion: The remaining fluid containing concentrated nitrogenous wastes (mainly urea) forms urine, which is collected in the collecting duct and sent to the urinary bladder via the ureters.