The Digestive System A. 1.

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Date
Class
Lesson Outline
LESSON 2
The Digestive System
A. Functions of the Digestive System
1. All
that a person eats goes through four steps—ingestion,
digestion, absorption, and elimination.
2.
is the act of eating, or putting food in the mouth.
3.
is the mechanical and chemical breakdown of food into
small particles and molecules that your body can absorb and use.
4.
occurs when the cells of the digestive system take in
small molecules of digested food.
5.
is the removal of undigested food and other wastes
from the body.
B. Types of Digestion
1. In
, food is physically broken into smaller pieces.
2. In
, chemical reactions break down pieces of food into
smaller molecules.
3.
are proteins that help break down large
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molecules into smaller molecules. They also speed up, or catalyze, the rate of
reactions.
do not change in
the reactions.
4. The digestive system produces enzymes that are specialized to help break down
each type of food
.
C. Organs of the Digestive System
1. The digestive system is made of two parts: the
and the
other organs that help the body break down and absorb food.
2. Mechanical digestion of food begins in the
3.
.
contains an enzyme that helps break down
carbohydrates.
4. The
is a muscular tube that connects the mouth to the
stomach.
5. Food moves through the esophagus and the rest of the digestive tract by waves of
muscle contractions, called
Digestion and Excretion
.
29
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Lesson Outline continued
6. The
is a large, hollow organ that stores food and aids in
chemical digestion.
a. The stomach contains a(n)
fluid called gastric juice.
As food mixes with gastric juice in the stomach, it forms a thin, watery liquid
called
.
b. Gastric juice contains
, an enzyme that helps break
down protein.
7. Chemical digestion of proteins, carbohydrates, nucleic acids, and fats takes place in
the first part of the small intestine, called the
.
8. The folds of the small intestine are covered with fingerlike projections
called
9.
.
move from the small intestine into the blood through
small blood vessels in the villi.
10. The pancreas,
, and gall bladder produce substances that
enter the small intestine and help with chemical digestion.
11. As food travels through the large intestine,
is absorbed.
12.
in the intestines digest food. They also produce
important
and amino acids.
D. The Digestive System and Homeostasis
1. Nutrients from the digestive system are necessary for other body systems to
maintain
.
2. Blood in the circulatory system carries nutrients from digestion to all other body
systems, providing these other systems with materials that
contain
30
.
Digestion and Excretion
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Materials that pass through the large intestine are the
products of digestion.