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Human Biology Key Notes

Our energy is derived from food - whereas plants can produce their own energy from
sunlight, we must consume food

This food is our raw material - needed to make new substances for: -
Energy (movement etc...)
Growth and repair

A balanced diet contains the…

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Different people need different amounts of food. You need more food if you are
particularly active, are pregnant etc... (the amount of energy food contains is
measured in kilojules (kJ) - if you are more active, your kJ intake needs to be
greater )

If we eat too little food,…

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Kwashiorkor ­ too much carbohydrate and no protein
Anorexia ­ too little food

RDA is the amount of a specific nutrient which is recommended for consumption per
day ­ food packaging must clearly show this for each nutrient

A balanced diet should contain fats, proteins and carbohydrates in roughly these…

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High blood pressure can lead to heart disease by straining the heart and damaging the
blood vessels

Normal blood pressure is 120/80 ­ overweight people and those who eat too much
salt often have high blood pressure

The heart is an organ that needs its own supply of blood to…

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Bile acids
Insulating nerve fibres

The bloodstream transports cholesterol around the body attached to proteins

The combination of cholesterol and protein is called lipoprotein, and there are two
type: -
Low-density lipoproteins (LDLs) - carry cholesterol from the liver to the
High-density lipoproteins (HDLs) - carry excess cholesterol back…

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Saturated oils tend to be solid at room temperature, and are sometimes called
vegetable fats instead of oil ­ lard is an example of a saturated oil

The fatty acids in some vegetable oils are unsaturated, and have double bonds
between some of their carbon atoms
Unsaturated oils tend to…

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One easy way to defend the body against illness is by keeping it clean and hygienic as
microbes can spread very quickly in unhygienic conditions ­ the spreading of
microbes is known as transmission

As soon as a virus or bacterium enters the body, we are termed infected (not the…

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Viruses consist of a fragment of genetic material inside a protective protein coat

Viruses can only reproduce inside host cells, and they damage the cell when they do
this ­ if a virus can get inside a cell it can take it over and make hundreds of
thousands of copies…

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In the late 1840's Dr. Ignaz Semmelweis noticed that the death rate in a delivery
room was high

He thought that the doctors were carrying infections between patients and ordered
doctors wash their hands with a chlorinated solution before examining women in

The mortality rate in his maternity wards…

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Phagocytes can easily pass through blood vessel walls into the surrounding tissue and
move towards pathogens or toxins

They then either ingest and absorb the pathogens or toxin; or release an enzyme to
destroy them

Having absorbed a pathogen, the phagocytes may also send out chemical messages that


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