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The Digestive System
Part 2
Objectives:
Explore the different parts of the
Digestive System
The Pancreas
When chyme leaves the stomach, it is very acidic. The
pancreas makes fluids to protect the small intestine from the
acid. The pancreas is located between the stomach and the
small intestine. The chyme never enters the pancreas.
Instead, the pancreatic fluid flows into the small intestine.
The fluid contains enzymes that chemically digest the chyme.
The enzymes contain bicarbonate, which neutralizes the acid
in the chyme.
The Small Intestine
The small intestine is a muscular tube that aids in digestion.
The inside wall of the small intestine is covered with fingerlike
projections called villi. These villi are covered with tiny,
nutrient absorbing cells. Once the nutrients are absorbed by
the villi, they enter the bloodstream.
The Liver and Gallbladder
The liver is a large, reddish brown organ that also helps with
digestion. It is located on the right side of the body, placed
slightly higher than the stomach.The liver helps by:
1.
Making bile to break up fat
2.
_Storing nutrients_
3.
Breaking down toxins
Breaking Up Fat
Bile is made by the liver, and is stored in the gallbladder
temporarily. The gallbladder is a small, saclike organ located
by the liver, intestines and stomach. Bile is squeezed from
the gallbladder into the small intestine, where it breaks up
large fat droplets into very small ones. This allows more fat
molecules to be exposed to the enzymes.
Storing Nutrients and Protecting the Body
After all the nutrients are broken down, they are absorbed
through the bloodstream and are carried throughout the
body. Nutrients that are not needed right away are stored in
the liver, where they are later released into the bloodstream
as needed. The liver also captures and detoxifies many
chemicals in the body. It is useful for producing enzymes that
break down alcohol and other drugs.
The End of the Line
Material that can't be absorbed into the blood is pushed into
the large intestine. The large intestine is the organ of the
digestive system that stores, compacts, and then eliminates
indigestible material from the body. The large intestine
absorbs most of the water in the mixture that has entered its
realm and changes the liquid into waste material called
feces, or stool. Whole grains, fruits, and vegetables contain a
carbohydrate called cellulose, otherwise known as fiber.
Humans cannot digest cellulose. Fiber keeps the stool soft
and keeps the material moving through the large intestine.
The rectum is the last part of the large intestine. The rectum
stores feces until they can be expelled from from an opening
on the outside of the body, the anus. It takes about 24 hours
for your lunch to pass through your digestive system.