briefly describe the mechanism of urine formation.

 

The mechanism of urine formation takes place in following steps-

(i) Ultrafiltration- All the blood components are filtered by the kidneys except for the blood cells and the plasma proteins, e.g. urea, water, sodium, glucose, potassium,etc.

(ii) Selective reabsorption- The essential components are reabsorbed back into the blood vessels, e.g. glucose, water, sodium, etc.

(iii) Secretion- The movement of elements such as water, glucose, amino acids, urea etc from the blood into the nephron is known as secretion. For example, potassium ions and hydrogen ions are secreted by distal convoluted tubule (DCT) and uric acid and other toxic chemicals secreted by proximal convoluted tubule (PCT)

(iv) Then the water reabosprtion content is further regulated before coming out of the kidney through a hormone, anti-diuretic hormone (ADH).

(v) Urine is then formed, collected in the bladder and excreted outside the body.