As your body performs the many functions that it needs in order to keep itself alive, it produces wastes from the body, usually as urine or sweat. Urine includes urea, water and inorganic salts. These wastes can be toxic and if not removed they would seriously hurt or even kill you. The excretory system is responsible for collecting waste products and removing them from your body. The main parts of the excretory are the kidneys, ureter, urethra, bladder, liver, skin, and lungs. These are described in more detail below.
The kidneys are the main organ in the excretory system. They are two organs located on each side of the spine in the lower back. As your blood travels in your body, it becomes polluted with urea and other wastes. Eventually the blood enters your kidneys and they act like a filter for the blood. As the blood enters your kidneys it is cleaned. Your kidneys remove the urea from the blood, sends it to your bladder for storage in the form of urine (pee). It takes about 45 minutes for your kidneys to completely filter all of the blood in your body. If the kidneys fail to function, poisons build up in the body, eventually causing death.
The Ureter carries the urine from the kidneys to the bladder. Each kidney has one ureter. As urine is made by each kidney, it moves it into the ureter. The ureter contracts and releases at about three times a minute. The pulsing motion forces the urine down the tube and empties it in the bladder in spurting motion.
The Urethra is the tube that carries the urine from the bladder to outside the body. After being stored temporarily in the bladder, the urine passes out of the body by way of the urethra.
The bladder fills up with the urine being produced by your kidneys until it becomes full. Once full you will feel a need to go to the bathroom. Urine leaves your body through the process of urination, (what we call peeing).
The Liver is a vital part of the excretory system, and it is the largest gland in the body. One of its most important tasks is to help the body digest food. The liver also changes ammonia, which is a poisonous gas into urine and gets rid of the unneeded waste in the body.
Skin is our largest organ. Adults have about 8 pounds and 22 square feet of it. The skin gets rid of extra salts, water, and heat, in the form of sweat. The sweat gets rid of the waste fluids urea and lactate. The skin helps keep the internal temperature of the body within normal levels. The skins role as a part of the excretory system is very small compared to the rest of the organs.
Lungs are two-sponge like organs. The lungs are thought of normally as part of the respiratory system as the main function of the lungs is to bring oxygen from the air we breathe into the bloodstream. They are also a part of the excretory system in that they get rid of the carbon dioxide from the bloodstream every time you breathe out. The process of taking in good air and releasing the carbon dioxide all happens in air sacs in the lungs called alveoli.
It takes about 45 minutes for your kidneys to completely filter all of the blood in your body.
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