Digestion and

Enzymes

Digestion

Digestion is the breaking down of food

There are 2 types of digestion:

1. Physical Digestion

2. Chemical Digestion

Physical Digestion

Physical Digestion is when teeth cut and

chew food into smaller pieces.

Physical digestion happens in the mouth

It also happens in the stomach when it

churns our food

Chemical Digestion

Chemical Digestion is when enzymes

break food down into smaller pieces

An example of chemical digestion is

when enzymes in saliva break starch

down

Also acid in the stomach breaks food

down

Teeth

Teeth

There are 4 types of teeth:

1. Incisors

2. Canines

3. Premolars

4. Molars

A human adult should have 32 teeth

Teeth

Enzymes

Enzymes

Enzymes are chemicals made in our body

that speed up chemical reactions in our

body, like breaking food down.

It just means enzymes help break food

down faster

Enzymes

There are hundreds of different types of

enzymes in our body.

Each enzyme will only help break down

certain types of foods e.g. One enzyme

might only break fat down and another

might only break sugar down

Enzymes

Example of Enzyme Action:

An enzyme is found in our saliva (spit)

This enzyme is called Amylase

Amylase will only break down starch

Amylase breaks starch down into maltose

Enzymes

Enzyme = Amylase

Substrate = Starch

Product = Maltose

The 5 stages in Digestion

1. Ingestion

2. Digestion

3. Absorption

4. Assimilation

5. Egestion

The Digestive System

The Digestive System

Mouth Esophagus

Liver

Anus

Stomach Pancreas Large intestine

Small intestine

Rectum

The parts of the

digestive system

The parts of the digestive

system

The Mouth

Food is taken into the body through the

mouth

The Oesophagus

Food travels down the oesophagus to

get to the stomach

The parts of the digestive

system

The stomach

The stomach stores food for a couple of

hours

HCL acid breaks food down

Enzymes made in the stomach break food

down

The parts of the digestive

system

The small intestine

The small intestine makes enzymes which

break food down completly

Nutrients from the food is absorbed into

the blood and sent all around the body

The parts of the digestive

system

The Liver

The liver makes a liquid called bile

Bile goes from the liver into the small

intestine

Bile helps digest fat in the small intestine

The parts of the digestive

system

The Pancreas

The pancreas makes enzymes

The enzymes go from the pancreas into

the small intestine where they help break

food down

The parts of the digestive

system

The large intestine

The large intestine absorbs (takes out) a

lot of the water from the digested food

If not enough water is absorbed in the

large intestine = diaharea

If too much water is absorbed =

constipation

The parts of the digestive

system

The Rectum

Faeces are stored in the rectum

The Anus

Faeces pass out of the anus

An Experiment to show the

action of Amylase on Starch

Put starch into a test tube

Put starch and amylase into another test tube

Wait 10 mins

Put iodine into both test tubes.

The starch turns blue/black The starch and amylase turns

red/brown because the amylase broke all the starch down