# What is excretory system?

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The excretory system is very important to your body and only has a few parts. In a similar way to removing solid waste from your body, you must also get rid of fluids. You know the results of the excretory system as urine.

The Excretory system is responsible for the elimination of wastes produced by homeostasis.

There are several parts of the body that are involved in this process, such as sweat glands, the liver, the lungs and the kidney system.

Every human has two kidneys.

Each kidney is made up of three sections: the renal cortex, the renal medulla and the renal pelvis.

The blood arrives at the kidney via the renal artery, which splits into many afferent arterioles.

These arterioles go to the Bowman's Capsules of nephrons, where the wastes are taken out of the blood by pressure filtration.

Peritubular capillaries also surround the nephron so substances can be taken in and out of the blood.

The renal cortex is the outer layer of the kidney and the medulla is the inner layer of the kidney.

The renal pelvis takes urine away from the kidney via the ureter.

Both of the ureters lead the urine into the body's only urinary bladder, which expands and sends nerve impulses when full.

From there, urine is expelled through the urethra and out of the body.

Some Amazing Facts:
• The kidneys function as a pair of filters through which about one litre of blood circulates each minute. The entire blood in the body passes through them in 5 - 6 minutes. In a day it filters 1800 litres of blood which is 400 times the blood volume.
• Tea, coffee and alcohol are beverages that increase the formation of urine. They are termed diuretics.
• The human kidney contains more than 1.2 million nephrons.
• When a kidney is damaged or diseased, the other kidney is able to compensate for it. So a person can lead a normal life with only one kidney.
• A normal adult excretes 1 - 1.8 litres of urine per day.
• An artificial kidney (dialysing machine) is used for dialysis. When the kidneys of a patient stop functioning, life can be prolonged through dialysis.
• Kidney transplants have had good success rates and have given fresh lease of life to patients.