The Digestive System

The Functions of the Digestive System1. Ingestion: when food enters the mouth

2. Digestion: when food is broken down

3. Absorption: when the body absorbs nutrients from food

4. Elimination: when the body gets rid of wastes

Digestion

• The process that breaks down food into small molecules so that they can be absorbed and moved into the blood.– Mechanical digestion: when food is chewed,

mixed and churned.– Chemical digestion: when chemicals break

down large molecules of food into smaller ones.

Enzymes

• Types of proteins that speed up the rate of a chemical reaction in your body– Amylase: made in the mouth.

• Breaks complex carbohydrates into simple sugars.

– Pepsin: made in the stomach• Breaks proteins down into amino acids.

– Pancreas: organ located behind the stomach• Releases several enzymes into the small intestine to

continue the break down of foods.

– Additional enzymes aid other important chemical reactions which are essential for numerous body functions.

Parts of the Digestive System

Digestive Tract

1. Mouth

2. Esophagus

3. Stomach

4. Small intestine

5. Large intestine

6. Rectum

7. Anus

Accessory Organs

1. Tongue

2. Teeth

3. Salivary

glands

4. Liver

5. Gallbladder

6. Pancreas

Functions of the Digestive Organs

Body Part Function Extra Info

Mouth Mechanical & Chemical digestion begins here Contains saliva glands

Esophagus Muscular food that food passes though to stomach

Keeps food moist (25 cm long)

Peristalsis: waves of smooth muscle contractions that move food through the digestive tract

Stomach Muscular bag where mechanical and chemical digestion take place

Hydrochloric acid helps break down food and kill bad bacteria

Chyme: a thin, watery liquid that food is changed into after it has moved through the stomach

Small Intestine

Most digestion takes place in the duodenum, the first section of the small intestine

Fats are broken down and stomach acids are neutralized

Absorption of food into the body happens here

Peristalsis also continues here

Villi: Fingerlike projections that increase the surface area of the small intestine so nutrients have more places to be absorbed

Large Intestine

Absorbs water from undigested stuff

Helps with Homeostasis

Chyme can stay in here for as long as three days

Rectum & Anus

Control the release of semisolid wastes from the body as feces

Functions of accessory organs

Body Part Function

Tongue Moves food around and mixes it with saliva

Teeth Crush food into smaller pieces. Responsible for mechanical digestion in the mouth

Salivary Glands

Supply saliva, which is a mix of water, mucus and an enzyme that breaks down starches into sugar. There are three sets of salivary glands near the mouth

Liver Produces bile, which breaks down large fat particles much like detergents break up grease

Gallbladder Stores bile and increases its potency before it released into the duodenum

Pancreas Produces enzymes and a digestive solution that contains bicarbonate ions, which neutralize stomach acid. Also produces insulin which allows glucose to diffuse into the body’s cells

Bacteria are Important!• Live in the organs of

the digestive tract• Feed on undigested

materials and make vitamins like K (assists in clotting)

• Converts bile pigments into new compounds

• Breakdown on intestinal materials produces gas