Q.Write the functions of Human Kidney.

Renal physiology simply means how the kidneys work — the day-to-day business of cleaning the blood and turning what needs to go into urine. A helpful everyday image is a busy recycling plant: raw material pours in, useful bits are pulled back out and returned, a few extra wastes are added in, and only the true rubbish is sent out at the end.

At the heart of it is the nephron, the functional unit of the kidney, and each kidney has close to a million of them. A nephron works in three linked steps. First comes glomerular filtration, where blood pressure in the glomerulus pushes almost everything except plasma proteins out of the blood and into Bowman's capsule — a very fine filtering that is called ultrafiltration. Second comes reabsorption, where nearly ninety-nine per cent of that filtrate is taken back into the body; glucose, amino acids and sodium ions are pulled back actively, while much of the water and the nitrogenous wastes move back passively. Third comes tubular secretion, where the tubule cells add certain substances such as hydrogen ions, potassium ions and ammonia into the filtrate. …