Download Student Writing Sample- Digestive System

Camilo
8/29/2011
Digestive System
The digestive system helps us break down food so we can use the
nutrients in it. It all starts in the mouth. Two processes take place in the
mouth, the chemical digestion and the chemical digestion. The
mechanical digestion is the act of chewing food so it can break down
and can be swallowed more easily. The chemical digestion is when
chemicals in your spit called enzymes break down food into molecules
that can be absorbed by the body. The name of the enzyme in your spit
is salivary amylase. When the food turns into a gooey mass, the tongue
pushes it into the entrance of the esophagus.
The esophagus is a tube that connects your mouth to your
stomach. It takes about six seconds for the food to go from the
esophagus to the stomach. The esophagus is about 30 cm long. The
next stop is the stomach. In the stomach the food mixes with enzymes
and hydrochloric acids to break down proteins and fat. After 4our hours
in the stomach the food turns into a thick milk shake called chime. Cool
facts about the stomach are that it is the size of a clenched fist, but it
can expand to hold up to 5 liters, and that if it didn`t have a lining of
mucus the acids would burn it.
A hormone called c.c.k. relaxes a certain muscle so that food can
get from the stomach to the small intestine. When the chyme is in the
duodenum, the entrance of the small intestine, the liver produces bile.
Bile is a substance that helps break down nutrients and fat small
enough to be absorbed into the blood stream. The liver produces the
bile and the gall bladder stores it. When the body detects chyme
entering the duodenum the gall bladder shoots bile at it. The gall
bladder is cool because it is pear shaped. The pancreas creates juices
that neutralize the acids from the stomach. If you didn’t have a
pancreas your small intestine would burn.
Next, the food goes into the small intestine. There villi absorb
nutrients into the bloodstream. Did you know the small intestine is 7
meters long? It would need to be 3km to absorb all the nutrients if it
didn`t have villi.
Now, the food is almost there. After the small intestine is the
large intestine. When the food goes through the large intestine it gets
most of its water absorbed. When you have diarrhea your large
intestine doesn’t absorb the water and you get dehydrated. Finally the
food reaches the end of the small intestine, the rectum, and it comes
out by the anus.