The nephron is the functional unit of the kidney responsible for the filtration, reabsorption, and secretion of various substances. It consists of two main parts: the renal corpuscle and the renal tubule.

Renal Corpuscle:
The renal corpuscle is the initial part of the nephron and is composed of the glomerulus and Bowman's capsule. It is responsible for filtering blood and producing urine.

- Glomerulus: A network of tiny blood vessels that filters blood and removes waste products.
- Bowman's capsule: A cup-shaped structure that surrounds the glomerulus and collects the filtered blood.

Renal Tubule:
The renal tubule is a long, coiled tube that extends from Bowman's capsule and is responsible for reabsorption and secretion.

- Proximal convoluted tubule: The first part of the renal tubule where most of the reabsorption of water, glucose, amino acids, and ions takes place.
- Loop of Henle: A U-shaped section of the renal tubule that concentrates urine by reabsorbing water and ions.
- Distal convoluted tubule: The final part of the renal tubule where selective reabsorption and secretion of ions and drugs occur.
- Collecting duct: A series of tubules that collect urine from several nephrons and transport it to the renal pelvis.

Overall, the nephron plays a crucial role in maintaining the body's fluid and electrolyte balance by regulating the amount of water and solutes that are excreted in the urine.