THE DIGESTIVE SYSTEM
A Study Guide
Mr. Ardito’s Living Environment

The purpose of the
Digestive System
To make big things into small things

The Parts of the Digestive
System

The Mouth
Teeth grind food into
swallowable substance (bolus)
Enzymes in saliva start to break
down starches.

Esophagus
Muscular contractions
move the bolus to the
stomach
These contractions are
called peristalsis
No new digestion
occurs

Stomach
Stomach is very muscular and
churns the food into a paste
(chyme).
Stomach makes acid which helps
break down proteins.

Small Intestine
No new mechanical
digestion takes place.
Enzymes break down
proteins, starches, and fats
Nutrients are absorbed
into the bloodstream via
the villi.

Large Intestine
Undigested food (now
called feces)passes into the
large intestine.
Water, minerals, and
vitamins are reabsorbed.

Anus/Rectum
The rectum stores feces
until it is ready to be
released.
The anus is the opening
through which feces is
released.

Types of Digestion
Part Mechanical Chemical
Enzymes from
Mouth Chewing
saliva
None (still
Esophagus None continuing from
mouth)
Acid from gastric
Stomach Churning of Food
juice
Small Intestine None Enzymes
Reabsorption of
Large Intestine None water and
minerals

Enzymes
Enzymes are chemicals that speed up chemical reactions.
Enzymes used in digestion help break big things into small
things.
3 types of enzymes
Proteases - act on proteins
Amylases - act on starch
Lipases - act on fats