4- The excretory system

The excretory system eliminates waste products from our body. Our body excretes carbon dioxide, urine and water. The excretory system is made up of the urinary system and the sweat glands.

A) The urinary system.

The urinary system is the principle way in which the body gets rid of waste

from blood. It is made up of:

• The renal arteries carry blood to the kidneys.
• The kidneys eliminate water and waste products from the blood. This combination  forms urine.
• The ureters are the tubes which transport urine from the kidney to the bladder.
• The bladder is a kind of bag that collects urine.

When the bladder is about half-full, it sends signals to the brain that it needs to be emptied. This is when you want to go to the toilet!

• The  urethra is a tube through which urine leaves the body. It empties urine from the bladder.

B) The sweat glands. 

They are small tubular structures of the skin that produce sweat.Our body also eliminates waste products through the skin. 

When we get hot, sweat glands in our skin are activated to cool down the body. These glands excrete sweat which is a mixture of water and minerals. Sweat leaves our body through pores