The Digestive System

A Study GuideMs. Bennett’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)

Mechanical and chemical digestion take place here

Enzymes in saliva start to break down starches.

EsophagusMuscular 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 IntestineNo 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 DigestionPartPart MechanicalMechanical ChemicalChemical

Mouth ChewingEnzymes

from saliva

Esophagus

NoneNone (still continuing

from mouth)

StomachChurning of

FoodAcid from

gastric juiceSmall

IntestineNone Enzymes

Large Intestine

None

Reabsorption of water

and minerals

EnzymesEnzymes 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