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A balanced diet

Diet is the usual food and drink that each person consumes and is a very important part of health.

A balanced diet means eating the right types of food in the right amounts so that the body gets the nutrients it needs.

What are the seven nutrients needed in a balanced diet?

Which foods contain these nutrients, and why are they important?

carbohydrates

proteins

fats

vitamins

minerals

water

fibre


Getting the amounts right


Types of nutrients


Nutrients in food


Eating too little

There are several reasons why people might not have enough food, including:

Many people do not have access to enough food. A lack of nutrients can result in malnutrition. Malnutrition is a major health problem. It increases the risk of disease and early death.

A lack of just one specific nutrient can cause a deficiency disease, like anaemia or scurvy.

natural disasters

poverty

war


Eating too much

Eating too much means that the body consumes more energy than it uses and so the excess starts to build up.

People who are very overweight for their height are said to be obese. Currently, 17% of 15-year-olds in the UK are classified as being obese.

Obesity is a serious health problem as it affects the heart, blood pressure and can lead to joint problems.


Deficiency diseases


Digestion


The stomach

As food moves through the digestive system it is broken down. Useful food molecules and water are absorbed into the body.

the chemical breakdown of food begins

microbes are destroyed.

From the stomach, food enters the small intestine where digestion is completed and the small digested food molecules are absorbed into the bloodstream.

After food is swallowed, it enters the stomach.Two things happen to food in the stomach:

food enters from the gullet

muscle tissue

food leaves the stomach


The intestines

After the small intestine, the remains of the food travels to the large intestine. All that is left of the food is water and waste material.

The water is valuable, so it is absorbed from the large intestine into the bloodstream.

The undigested waste travels to the rectum where it is stored until leaving the body through the anus.

The waste material cannot be digested or used by the body.

largeintestine

smallintestine


Organs of the digestive system


What is digestion?

The body carries out digestion of food to convert large insoluble food molecules into smaller soluble ones.

Large food molecules cannot pass through the walls of the small intestine. Small food molecules can do this when dissolved in the bloodstream. Why is this important?

carbohydrate molecule

fat molecule protein

molecule


What are carbohydrates?

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

The body breaks down long chains of carbohydrates into the smaller sugar molecules.

These small sugar molecules are used by the body to release energy and make the body work.

carbohydrate molecule

one sugar molecule


What are proteins?

Proteins, like carbohydrates, are made of long chains of small molecules. In proteins, these small molecules are not identical.

Proteins are made up of chains of small molecules called amino acids. There are over 20 different kinds of amino acid.

Proteins are used by the body for growth and repair.

protein molecule

one amino acid


What are fats?

Fats are made up of fat molecules, which contain fatty acids and glycerol.

Fat molecules have to be broken down by the body so that they can be used for energy storage.

Fats are also used by the body to keep heat in and to make cell membranes.

fat molecule

glycerol fatty acids


Digestive enzymes

How do digestive enzymes help the process of digestion?


Different types of digestive enzymes

Digestive enzymes are the chemicals that break large insoluble food molecules into smaller soluble molecules.

Digestive enzymes are classified by the type of food that they affect; there are three main types:

carbohydrase – breaks carbohydrate into smaller sugars

protease – breaks protein into amino acids

lipase – breaks fat into fatty acids and glycerol.


How do enzymes work?


Carbohydrate digestion

Carbohydrates are chains of identical sugar molecules.

The digestive enzyme called carbohydrase breaks the chemical bonds between the individual sugar molecules in each carbohydrate chain.

long carbohydratemolecule

sugar molecules

carbohydrase


Protein digestion

Proteins are made up of amino acids. There are over 20 different types of amino acids.

Proteins are digested by digestive enzymes called proteases. These enzymes work in an acidic environment to break proteins into smaller amino acids.

long protein molecule amino acid molecules

protease


Fat digestion

Fats are digested in two stages.

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

Secondly, the digestive enzyme lipase breaks each fat molecule into the smaller glycerol and fatty acid molecules.

fat molecule glycerol fatty acids

lipase +

bile


Which enzyme?


The process of digestion


Label the digestive system


Summary


Fitness


What is health?

Health is a state of complete mental, physical and social well-being, and the absence of disease or infirmity.

So a healthy person is:

physically well

mentally well

socially happy

free from disease.

What is the difference between health and fitness?


What is fitness?

Fitness is the ability to meet the demands of the environment.So, fitness is not necessarily about how far you can run or how good you are at sport.

Being fit means being physically able to cope with the demands of everyday life.

These demands will vary from person to person, depending on things like lifestyle, occupation and age.


What is fitness?

Fitness is made up of four factors – “the four S’s”:

suppleness strengthstamina speed

fitness

How do these fitness factors help us in everyday life?


Fitness factors


Why exercise?

Regular exercise can help to keep you healthy, by:

Exercise also helps to maintain and improve fitness.

strengthening the heart, reducing the risk of heart disease

strengthening bones, reducing the chances of osteoporosis

reducing stress, by releasing mood-enhancing chemicals in the brain.


Why exercise?


Which factor?


Staying fit and healthy

How can poor exercise cause injury to muscles and joints?

However, exercise can be hazardous if done inappropriately. Injuries are common from lifting weights that are too heavy and running on hard surfaces without proper footwear.

You should aim to do a minimum of 30 minutes of moderately intense exercise at five times a week (or more).


Different types of joints


Summary activities


Glossary


Anagrams


Multiple-choice quiz

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