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The Digestive System
1. Name ______________________
The digestive system is a group of organs inside your body working together to
break down food into tiny molecules. Digesting food is important so that we can
have the energy to do everything we need to do.
Mouth: Physical and Chemical digestion
When food enters your mouth, it is acted upon in two ways: Physical digestion
begins when the food is chewed and broken down into smaller pieces by the teeth.
There are four types of teeth – Incisors, Canines, Premolars and Molars. While
you are chewing, your tongue moves the food around to the teeth. Chemical
digestion also occurs while you are chewing. Chemicals in your spit, called
enzymes, begin to chemically break down the food.
Oesophagus: Passes food to the stomach by peristalsis
After being chewed and swallowed, food travels through the esophagus which is a
long tube that runs from the mouth to the stomach. The muscles in the wall of
the oesophagus start to push the mushy food down into the stomach by moving in
waves. This action is called peristalsis. Peristalsis gives us the ability of being
able to eat or drink even when we’re upside-down!
Stomach: Physical and chemical digestion
The stomach is really nothing more than a mixing and holding area. The food is
churned and mixed together and then drenched in a very strong acid called
Hydrochloric Acid. This acid breaks the food down so in a short time, the food
becomes a think liquid which looks nothing like the food you ate.
Small Intestines: Absorption of food into the blood stream
After being further digested in the stomach, food enters the small intestine. The
small intestine is very long (about six meters long). It is called the small intestine
because it is narrow. The wall of the small intestine contain millions of villi,
which are tiny hair-like structures that absorb the nutrients in the food to be carried
to the blood stream and passed to all parts of the body.
Liver, Pancreas and Gall bladder: Additional help with digestion
As the food passes through the small intestine, the liver gives small amounts of
bile, which is a greenish liquid that helps digest fat. Bile is stored in the gall
bladder to be used when needed. The pancreas also produces enzymes
(chemicals) to help with digestion. One main job of the pancreas is to produce
insulin which helps regulate the level of sugar in the body.
At this point, most of the nutrients have been taken from the food and what is left
is prepared for removal from the body.
Large intestine: Absorption of water from the food
After passing through the small intestine, food enters the large intestine. The large
intestine is short, but is large around (which is why it is called the large intestine).
In the large intestine, most of the water is removed from the food. What is left is
pressed together and stored in the rectum to be removed through the anus.