In the human excretory system (Class 10 Biology), the kidneys act as the master purifiers of the body. They filter out poisonous waste (like urea) from our blood and expel it as urine. But what exactly does this microscopic filtering work?
If you were to take all the microscopic nephron tubes from just one of your kidneys and lay them out in a straight line, they would stretch for nearly 16 kilometers (10 miles)!
The basic structural and functional filtration units of the kidneys are called Nephrons.
There are roughly 1 million (10 Lakh) microscopic nephrons packed inside each human kidney!
Each nephron is a tiny filtering tube. Its two main parts are:
Why is the tube so long? Because the body needs to reabsorb all the 'good stuff' (like glucose, amino acids, and essential water) back into the blood, leaving only the toxic waste (urine) to be sent to the bladder.
If a large number of nephrons are destroyed (due to diabetes, high blood pressure, or infection), the kidneys fail to clean the blood. Toxins build up in the body, which is fatal. The patient will then require a machine to clean their blood, a process called **Dialysis**.
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