Whether it would be called the bathroom, restroom, toilet, can, or john
in America, the Water Closet, or more affectionately known as the W.C.,
in Europe, the cze-swo in Chinese, or the bano (bonyo) in Spanish,
every language has a place to go when someone really has to Go.
The Excretory system is the system that rids the body of all its wastes,
and involves the lungs to remove carbon dioxide from the body, the large
intestine in which solid wastes pass through, and the kidneys which remove
the bulk of the liquid waste. Some liquid waste evaporates from the skin,
and some leaves through the lungs, which can be seen as your breath condenses
on a cold day.
The urinary system is made up of the kidney, the bladder, and three tubes.
Liquid waste is produced in the kidneys and stored in the muscular bladder.
A kidney is a bean shaped organ
about 10 centimeters long and inside each are about 1 million capillary
clumps. As blood flows through the capillaries, certain substances move
from the blood through the capillary walls into the tubes.
Among the "garbage" and other waste products that are disposed
of by the excretory system, are extra salts and minerals. Also, quite a
bit of water is filtered out. H20 makes up 95% of the urine. By removing
water from the body, the kidneys maintain balance in the blood. In certain
illnesses some abnormal substances are found in the urine. A doctor, called
a urologist, can order an analysis or urinalysis of a patient's urine. A
urinalysis consists of testing the density, PH, sugar, protein, and blood
content of the urine. A microscopic examination of urine is done to look
for bacteria, crystals and others substances. Substances found, or not found,
are clues to the detective work a doctor must do to diagnose the disease.
The rockets are fired up and the spacecraft is primed for launching.
It's 5...4...3...2...1...Takeoff!. Astronauts in space have to deal with
many things including the intense G-force in leaving and reentering the
earth's atmosphere, as well as the unusual weightlessness experienced.
Astronauts must also take the necessary food and water with them for their
mission. Since regular food is too heavy due to the great amount of water,
specially prepared freeze dried food is taken along. In this method, food
weighs 1/10 of what it would. The hungry space traveler just adds water
and Abracadabra! A delightful meal is prepared.
But one must wonder what happens to all the waste collected on the spaceship
on the months of the mission. Liquid wastes such as perspiration and urine
are sent through a specialized purifying system. This separates the water
from the other waste products. The water is purified further and is used
for drinking, washing, and preparing food. Solid waste materials are stored
in plastic waste bags and disposed of later after landing.
The excretory system, like anything else, is subject to breakdowns from
time to time. This, however, is very detrimental to the body. It is like
the garbage can in your house. Trash is thrown there, and later taken outside
to be removed. But, what happens when the garbage men go on strike? The
bags are thrown out onto the curb, but no one comes to pick them up. More
and more bags are thrown outside, and bag after bag after bag collects,
until the yard is a sordid, stinky mess of putrefying ooze. This is what
happens in the body also. One disease, known as Uremia, is a malfunction
of the kidneys. Wastes can not be excreted, so they build up in the body.
Another disorder is a urinary tract obstruction. This also causes urine
to be forced to stay in the kidney that produces a very harmful accumulation
of waste.
All animals must have a way to rid their bodies of excess waste, but
the makeup of the urine, how, and where it is excreted are different in
each animal. The composition of urine usually is in proportion with the
water requirements of the organism. Animals that live in lakes, ponds, or
other bodies of fresh water, excrete dilute urine because of the excess
of usable water to the body. Salt water or marine mammals, on the other
hand, excrete very little and very concentrated waste. Terrestrial animals
also excrete very concentrated urine.
In birds and reptiles, the waste is usually a whitish liquid of uric acid
crystals. You have of course witnessed this when a flying birds excretes
on your car. The urine of terrestrial insects is solid and is sometimes
stored as pigments, instead of being removed. In most animals, the kidneys
form a temporary area for urine to be stored, but the urinary bladders of
amphibians are pockets in the cloaca, and in fish they are expandable part
of the urinary duct.
Images copyright PhotoDisc, Inc., 1996.
Images copyright T/Maker Company, 1996.
New Book of Knowledge, 1987. Grolier Inc.