If you knew there was poison hidden in your house, you would surely do everything possible
to find and remove that poison. If you didn't, you and your family would slowly die. How
would you find it? How would you remove it? You would probably figure out a system
of searching and removing. That would be an excretory system.
Your body does the same thing every day. Hidden throughout your body are dangerous poisons
that must be removed in order for it to survive. The process of excretion involves finding
and removing waste materials produced by the body.
The primary organs of excretion are the lungs, kidneys, and skin. Waste gases are carried
by blood traveling through the veins to the lungs where respiration takes place. Dead cells
and sweat are removed from the body through the skin which is part of the integumentary system.
Liquid waste is removed from the body through the kidneys. Located beside the spine in
your back within your ribcage, the kidneys are small (about 10 centimeters long)
reddish-brown organs that are shaped like beans.
During circulation, blood passes through the kidneys in order to deposit used and unwanted
minerals, and a nitrogen-rich molecule called urea. The kidneys filter the wastes from the
forming a liquid called urine. The kidneys funnel the urine into the bladder along two
called ureters. The bladder stores the urine until muscular contractions force the urine
out of the body through the urethra. Each day, your kidneys produce about 1.5 liters of
urine. All of it needs to be removed from your system. This occurs through urination.
If your kidneys are diseased and not working properly, the buildup of waste in your system
eventually lead to death. Some kidney diseases can be treated with medication. Severe
diseases require more intense treatment. One treatment is called dialysis. The patient's
pumped through a dialysis machine which filters the waste from the blood and returns the
blood. A dialysis patient has to spend nearly sixty hours each week attached to the
The most radical treatment for kidney disease is a kidney transplant. Healthy people can
comfortably with only one kidney. Therefore, their other kidney can be donated to a person
kidney disease. The donor and patient must have very similar genetic structures in order
patient to accept the new kidney without complications. The patient also receives
drugs. During a kidney transplant operation, the healthy kidney is placed in the abdomen
patient and attached to the blood vessels and bladder. The patient's original kidneys are