Digestive System "
system is he system that digests the food
and removes it from the body.
There are many steps in this system. Step one begins when you take a bite
of food. As your teeth cut, grind, and tear the the food, three sets of
glands make saliva.
These glands are in front the ears, under the tongue, and under the lower
jaw. Little small tubes carry the saliva from salivary glands to the mouth.
then there is the esophagus.
the esophagus of a grown - up is about 25 centimeters long. Muscles in
the esophagus contract and relax to shove swallowed food down to the stomach.
This procedure is something like squishing toothpaste out of a tube.
The next step is the stomach.
It is a baglike organ with muscular walls. The muscles in the stomach squeeze
and mix food with digestion juice. This juice is made in the stomach's
lining. The juice changes the food, which stays in the stomach for two
to four hours. When food goes out of the stomach it is a thick liquid.
The small intestine
is next. The small intestine is a small curled-up tube that the liquid
is pushed into. Most digestion takes place here. If it was stretched out
an adults small intestine would be about 7 meters long. Most digestion
takes place in the three to six hours that food stays in the small intestine.
Juices that are made in the lining of the small intestine and some other
organs mix with food. These juices change food into nutrients.
The nutrients go through the very thin wall of the blood vessels in the
intestinal lining. This blood moves these nutrients, to the body cells.
The last step is the large
intestine. The parts of the food that
cannot be digested go through to the large intestine, with some liquids.
The large intestine takes out a lot of the liquids, and stores the resulting
solid wastes until in leaves the body.
Your cells don't like some foods or dislike some food. Some nutrients give
you the energy that you need to work, play, and do all kinds of things.
Some help you to grow and some make your body work right. Your digestive
system does this job, it is called digestion.
Your saliva makes your food wet so it is easier to digest. Saliva contains
is a chemical that helps break down the food you eat. It helps turn starches
into sugar. When you swallow the food it enters a tube called the esophagus.
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