Made LF: Oyegoke D.O

Food & Digestion

What is FOOD?

***Any nutritious substance that people or animals eat or drink or that plants absorb in order to maintain life and growth. is called “FOOD”.

Energy is used up as we go about our daily activities. With time the energy stored becomes almost empty and thus needs replacement.

Food is used by the body for:

RESPIRATION GROWTH REPAIR OF DEAD CELLS

CLASSES OF FOOD

There are five (5) classes of food:

CARBOHYDRATES

PROTEINS

FAT AND OIL

MINERAL SALTS

VITAMINS

WATER

WaterProtein

Mineral saltCarbohydrate

VitaminsFat & Oil

•Before food can be used by the body, it has to be broken down into smaller molecules for easy absorption.

•These small molecules are called the “end products”.

END PRODUCTS

FOOD CLASSES AND THEIR END PRODUCTS

FOOD CLASSES

Carbohydrates

Proteins

Fat and Oil

END PRODUCTS

Glucose

Amino Acids

Fatty Acids/ Glycerol

Why do we need food? We need to consume a balanced diet

which contains a variety of food in the proportions shown in the diagram below.

The body needs:

• Carbohydrates which provide energy.

• Proteins for repair and growth.

• Vitamins and minerals to keep the body healthy.

Food Groups

What is a balanced diet?

What do carbohydrates provide?

***Starchy foods contain carbohydrates, which are made of long chains of identical small sugar molecules.

Carbohydrate

1 Sugar molecule

The body has to break these large food molecules up into smaller pieces.

The small sugar molecules are very useful. The body can use them to make…

This energy is used to make the body work.

ENERGY

What do carbohydrates provide?

What do proteins provide?

As with carbohydrates, proteins are made of chains of chemicals. However, instead of the chain containing identical molecules, in protein these molecules are different.

Protein is made up of chains of amino acids(End Products). There are over 20 different kinds of amino acid.

Protein is used to allow the body to grow and to repair the body.

What happens to food in the “Digestive

System”?

Food enters the stomach, which is basically a muscular bag, filled with Hydrochloric acid (HCl). Two things happen here:• Chemical breakdown of the food.• Microbes are destroyed.

food enters from the gullet

cross section of stomach

digested food leaves

muscle tissue

The stomach

The large intestine

The remains of the food are then passed on to large intestine (colon).

All that is left is waste material and water. The body will want to leave the waste material within the digestive system but the water is valuable and so it is re-absorbed here.

The waste material is passed to the rectum where it is stored until it leaves the body through the anus.

Carbohydrates are chains of identical sugar molecules. The enzyme called Carbohydrase breaks the chemical bonds between the individual sugar molecules (called glucose) as part of digestion.

Starch/ Carbohydrates

Carbohydrase

Long carbohydrateSmall sugar

FatsFats are digested in two stages:

• Firstly, bile (released by the gall bladder) allows the fat to “mix” with water by breaking the fat up into smaller droplets. This is called emulsification.

• Secondly, an enzyme called Lipase breaks the fats down into the smaller fatty acid molecules and glycerol.

Bile

Lipase+

Fat

Fatty

acidGlycerol

After you have read and understood this topic, please attempt the quiz questions that follow in your blog. I hope you will find it tasking and interesting.