Explain the process of urine formation.

Process of urine formation includes following steps:

i. Blood along with the waste materials is brought to kidneys by the renal arteries.

ii. Ultrafiltration: There is a bunch of capillaries known as Glomerurlus is present in the Bowman’s capsule. As the blood passes through capillaries, it remains under pressure and is thus filtered out. This filtrate gets collected in the Bowman’s capsule.

iii. There are different tubular parts in the nephron like proximally convoluted tubule, Loop of Henle. In these tubules all the important substances like water, certain ions and amino acids are absorbed.

iv. After absorption of these necessary substances the remaining fluid only contains excretory substance and that fluid is known as urine. This urine is secreted back into tubular part which goes to collecting duct.

v. Several nephrons opens into a collecting duct into which they empties the urine which is further transferred to ureters and then to the urinary bladder.

In this way urine is formed in the human body. Following picture also depict the same mechanism: