Digestion and Nutrition

Trace food through the digestive system and name the nutrients the body needs.

~19 min Science

0 of 2 completed

Food must be broken down before the body can use it.

In this lesson you will:

Describe the main parts of the digestive system.
Name the nutrients in food and their uses.
Explain the role of enzymes.

The Digestive Journey

Food passes through a tube called the alimentary canal.

Mouth — teeth grind food; saliva contains amylase, which starts digesting starch.
Oesophagus — carries food to the stomach by peristalsis.
Stomach — acid and enzymes break down protein.
Small intestine — most digestion and absorption happen here.
Large intestine — absorbs water and forms waste.

Nutrients

The body needs carbohydrates for energy, proteins for growth and repair, fats for energy and insulation, vitamins and minerals for health, and water for transport and cooling.

Enzyme action

Starch is broken down by amylase into sugars.

Protein is broken down by protease into amino acids.

Fats are broken down by lipase into fatty acids and glycerol.

Warning A diet high in sugar and fat but low in fruit and vegetables can lead to obesity and deficiency diseases.

Practice

List the organs food passes through, in order.
Which enzyme digests protein, and where does it work?
Explain why a growing teenager needs protein every day.

Recap

Digestion breaks food into small, absorbable molecules. A balanced diet supplies every nutrient the body needs.

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Course contents

The Human Body

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