Who kidney structure

 Kidney 
Kidney is an excretory organ present in the human body. Kidneys act as excretory organs and also control the balance of water and mineral ions in the body. Kidney is divided into two parts namely, external region and internal region.

• External region is made up of a thick layer followed by a layer of fat. Fat acts as a shock absorber.
• Inner region comprises of renal cortex and renal medulla. The medulla is composed of conical masses of tissue that lead to pelvis. The cortex has a random arrangement of tiny tubules called nephrons which are the functional units of the kidney.

Nephrons are the microscopic basic filtration units of the kidney. Nephrons carry out an important process of urine formation in the kidney. Ultra-filtration is the first step in the urine formation in which nephrons filter minerals, waste and water but retain red cells, proteins and large molecules. A single nephron is made up of renal corpuscle and a renal tubule.
a) Renal corpuscle is made up of tangled clusters of tiny blood capillaries called glomerulus and Bowman’s capsule. 

• Glomerulus is called the filtration unit. 
• Bowman's capsule surrounds the glomerulus.

b) Renal tubule is made up of proximal convoluted tubule, Henle’s loop and distal convoluted tubule. 

• Renal tubule leads away from Bowman's capsule and becomes highly coiled to form the proximal convoluted tubule.  
• The tubule makes a hairpin loop, called the loop of Henle. It joins the distal convoluted tubule.
• The distal convoluted tubule opens into a collecting duct, which passes into the renal medulla.