Biology I (Human Biology) Key Notes

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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
Health
A balanced diet contains the different nutrients in the correct amounts, keeping us
healthy
Certain foods are not necessarily 'bad' for us, but eating too much of them could be
Foods contain nutrients: these are substances which provide raw materials for the
body (we need nutrients, along with fibre and water for a healthy diet)
There are seven different nutrients, and some foods are particular rich in certain
nutrients: -
Different foods contain different substances - there is no one food that contains all
the substances the body needs. Instead you must eat a wide variety of foods -
balancing your diet

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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, we will use up our store of fat and become too thin.…read more

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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
amounts: carbohydrates, fat and protein
Food labels on products show the RDA of different nutrients within the food, usually
per 100g and per serving of food...…read more

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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 keep it working ­ if the
blood supply is reduced, the heart muscle will not work properly and will become
weaker
A heart attack happens when part of the heart does not get any blood…read more

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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
cells
High-density lipoproteins (HDLs) - carry excess cholesterol back to the
liver
LDLs are often called 'bad' cholesterol because they lead to fat building up on
artery walls, which causes heart disease ­ 70% of cholesterol consisting mostly of fat
HDLs are often called…read more

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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 be liquid at room temperature, and are useful for frying
food ­ they can be divided into two categories: -
Monounsaturated fats have one double bond in each fatty acid
Polyunsaturated fats have many double…read more

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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
same as being ill ­ illness results from the effects these microbes have on our body
Bacteria and viruses have the ability to produce poisons known as toxins
There are two types of outbreaks: -…read more

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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 of itself
Eventually the virus copies fill the whole host cell and burst it open ­ the viruses are
then passed out in the bloodstream, the airways, or by other routes
Diseases caused by viruses…read more

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In the late 1840's Dr.…read more

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Lymphocytes
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
help nearby lymphocytes to identify the type of antibody needed to neutralise them
Pathogens contain certain chemicals that are foreign to the body and are called
antigens
Each lymphocyte carries a specific type of antibody -…read more

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