What is structural and functional unit of kidney?

The main unit of the kidney is called the nephron. It is the answer for both 'structural' and 'functional'. Each kidney has about one million of them, so they are very tiny but very important.

You see, the nephron is the real worker. It does the main job of the kidney. This job is to filter the blood. It removes all the waste products and the extra water from your body. This mix becomes the urine.

But it is also very clever. It takes back the useful things that your body needs to keep, like glucose and some salts. So, it is a very small and very smart filter. It is what makes the kidney work.