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Why do we need a digestive tract?
If the body did not have a digestive tract, you could not
enjoy your favorite pizza, hamburger, or other food. The human body
must obtain its energy by eating food. Therefore, the main purpose of the
digestive system is to provide the body with
amino acids,
carbohydrates,
fats, and
vitamins to keep our cells functioning. The digestive
system provides these essential materials to the 75 trillion cells that
live in our bodies. Wow! Do you know how many 75 trillion is?
The digestive tract takes both liquids and food and
breaks them down into single molecules that can be absorbed by cells in
the small intestine. These cells transport the molecules into the blood
stream so that other cells in the body can use them. The digestive tract
also serves to eliminate what your body doesn't absorb during the
digestive process.
 Why do I have a
stomach?
The stomach has two major functions in your body: one for
digestion and one for defense. (See the illustration on the right.).
Digestion breaks down proteins with acidic stomach juice, secreting
enzymes that split up proteins into individual amino acids (see
Cells Are Us unit on proteins). The defense component
kills most foreign organisms that you ingest so that they can't get into
your bloodstream or anywhere else in your body. These organisms are
destroyed by the highly acidic stomach fluid that is secreted within the
stomach.
Why do you have two intestines?
The intestines are where the body absorbs all of the food, vitamins,
fluid, and minerals that you eat. The intestines are long giving
your body a greater opportunity to absorb more of what you eat. The small
intestine breaks down proteins, carbohydrates, and fats so that they can
be absorbed into the body and the bloodstream. The large intestine is
where moisture is absorbed from what is left of the food. Anything that is
not absorbed by the intestines is then passed through as solid waste (or
feces).
 Why are the liver
and pancreas important in digestion?
Your liver secretes
bile into your small intestine. This bile contains worn
out red blood cells that must be removed from the body. If the old red
blood cells are not removed, they can become toxic. The bile
secreted by your liver also separates the fats that you eat so that they
can be broken down by enzymes. (See the picture on the right.)
Fat clumps together and when bile is not secreted into the small
intestine, your enzymes are less efficient at breaking down fats into
their fatty acid components.
The enzymes that break down these separated fats come
from the pancreas, as do those enzymes that break down carbohydrates and
proteins. The pancreas also secretes a basic solution that
neutralizes the acidic solution left over from the stomach.
The pancreas also secretes insulin, which helps move
glucose (blood sugar) from blood into cells. Diabetes is a common and very
serious disease that results from lack of insulin. For more information
about diabetes,
click
here.
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