Digestion

How it works

How do we get nutrients?

•Nutrients come from foods that we eat and digest.

Food is processed in the body in 3 phases:

• Ingestion

• Digestion

• Egestion

What is Ingestion?

The process of taking food into the body (eating).

• Occurs in the mouth

• During ingestion, mechanical and chemical digestion takes place in the mouth .

• Once food is swallowed, ingestion ends and digestion begins.

Ingestion:

Digestion

• Digestion breaks foods down chemically to access the nutrients the body needs.

• During digestion, larger pieces of food are broken down into smaller pieces mechanically and chemically.

• Complex chemicals in food are changed into simpler ones.

Digestion

• Begins in the esophagus and continues through the small intestine.

• Most digestion takes place in the stomach and small intestine.

• Nutrients are absorbed at the end of digestion.

Digestion: the process of breaking down food by mechanical and chemical action.

Egestion

• Egestion: removal of undigested food from the digestive tract.

•Water is absorbed from the undigested mass.

•Egestion occurs in the large intestine, rectum, and anus.

•Egestion only describes the removal of solid wastes.

Egestion

Label Your Diagram

Color the organs of the digestive system in based on which processes they are involved:

Ingestion = REDDigestion = BLUEEgestion= GREEN

How is food digested?

There are two types of digestion:

•Mechanical Digestion

•Chemical Digestion

Mechanical Digestion

MechanicalDigestion:

The breaking down of large food molecules by the movement of your teeth and tongue.

•Chewing food, and peristalsis is mechanical digestion.

•Food is crushed, cut, and mushed up to increase surface area.

•The surface area increases to aid with chemical digestion.

What are enzymes andwhat do they do?

•Chemical digestion can only take place with

enzymes and digestive juices.

•Enzyme: a substance that acts as a catalyst

to speed up the digestive process.

Enzymes are secreted by the

digestive organs to breakdown

food molecules

Enzymes of the Digestive System

•Amylase- salivary enzyme, begins the breakdown of carbohydrates.•Lipase- pancreatic enzyme, breaks down lipids.•Sucrase- small intestine enzyme, breaks down carbohydrates.•Pepsin- stomach enzyme, breaks down proteins.

Chemical Digestion

ChemicalDigestion:

The chemical breakdown of food into smaller molecules.

•Carbohydrates

•Proteins

•Fats

•Amino acids

•Fatty acids

•Monosaccharides and polysaccharides

Chemical Digestion

•Food is broken down to very small molecules and nutrients to be absorbed.

•The nutrient molecules are absorbed in the small intestine and carried by your bloodstream to diffuse into your cells.

Digestion episode

Digestion

http://kidshealth.org/kid/htbw/_bfs_DSmoviesource.html