Mention the purpose of formation of urine in human body. 

Solution:

Urine is formed in the nephron present inside the kidneys. There are four main steps through which urine is formed. They are as follows:

• Glomerular filtration – Due to very high pressure of blood in glomerulus (concentrated blood capillaries), the plasma only passes through it and the other substances including blood cells remain back into the filter and pass to the blood flow. The plasma is the filtrate here.

• Tubular reabsorption – The filtrate then enters the tubule where the necessary nutrients are absorbed again and returned back to the blood flow. The remaining filtrate then passes to the collecting tubule.

• Water conservation – In collecting tubule additional water is absorbed and a concentrated urine is formed.