ANSWERS : Digestive System Study Guide
Learning Standard 1.2c
The digestive system consists of organs that are responsible for the mechanical and chemical
breakdown of food. The breakdown process results in molecules that can be absorbed and
transported to cells.
Complete the chart by identifying the function of the main organs of the digestive system.
digestive organ
function
Mechanical and chemical digestion begins in the mouth. The teeth
mechanically break the food into smaller pieces as saliva’s enzymes
speed up chemical reactions.
1. mouth
1.
2. esophagus
2.
The esophagus moves the chewed food downward toward the
stomach. Muscle movements known as “peristalsis” help it to easily
move along.
3. stomach
3.
The stomach uses both mechanical and chemical digestion to further
break the food into nutrient molecules. It churns the food and adds a
strong acid and the enzyme pepsin to digest the proteins in the food.
4. liver
4.
5. small intestine
5.
The liver produces bile, which is used to break fat into smaller pieces.
The bile is stored in the gall bladder until it is needed by the small
intestine.
Most of the chemical digestion of food takes place in the small
intestine. Bile is squirted from the gall bladder into the small
intestine to break up fat particles. Enzymes from the pancreas
continue to break down starches, proteins, and fats.
Villi absorb the nutrient molecules into the blood stream for quick
delivery to the body’s cells.
6. large intestine
6.
The large intestine absorbs the remaining water. Bacteria work on
indigestible materials and make vitamins. Waste is prepared for
removal and sent to the rectum.
What is absorption?
Absorption is the process by which nutrient molecules are taken into (absorbed) into the blood
stream to be delivered to the cells of the body.
What role do the villi play in the process of absorption?
The millions of villi that line the walls of the small intestine contain a series of small blood vessels. The nutrient molecules
are able to pass through the walls of each villus and into the blood stream.
Why is peristalsis important to digestion?
Peristalsis is involuntary muscle contractions that take place in the esophagus. These contractions move the food down
the esophagus and into the stomach. The small and large intestine also use peristalsis to move the food through their
lengthy tubes.
Explain how each term relates to digestion:
enzymes
Enzymes are proteins that speed up chemical reactions in the body (pepsin). This allows organs to more
quickly digest food for the cells of the body.
bile
Bile is a substance that breaks up fat particles. It is produced in the liver and stored in the gall bladder and begins
the process of allowing fats to be digested.
blood
The blood is responsible for delivering the newly digested nutrient molecules to the cells of the body.
digestive process (defined)
mechanical:
The physical breakdown of food into
smaller pieces.
chemical: The use of acids and enzymes to change
the food into nutrient molecules.
organs involved (explain)
mouth: teeth break food into pieces
esophagus: forms food into a ball
stomach: churns food into a liquid
mouth: adds saliva to begin digestion
stomach: adds acid and enzymes (pepsin)
small intestine: adds bile and pancreatic enzymes
large intestine: bacteria work on indigestible material