Biology Unit 1

A balanced diet is a diet which contains all of the correct food groups:
Water- to transport other nutrients and stay hydrated.
Minerals- To keep healthy.
Proteins- For growth, repair and energy.
Carbohydrates- For a supply of energy.
Vitamins- To keep healthy.
Fibre- to keep the digestive system working well.
Fats- For energy, making cell membranes and insulation.

If you eat all of the nutrients with the correct amount of excercise you should stay healthy. If you don't eat the food in the correct amounts, you may become malnourished or suffer from defficiency

The metabolic rate is the speed at which all chemical reactions take place in the cells of your body. Some people have higher or lower metabolic rates depending on:
- Gender (men usually have faster metabolic rates than women.)
- Age (younger people have faster metabolic rates than older people)
- Muscle:Fat ratio. The greater the muscle to fat, the higher your metabolic rate will be.
- Genes.

A pathogen is a micro-organism that causes disease. There are two types of pathogens, Bacteria and Viruses. Bacteria can reproduce inside the body. They may produce toxins that make you feel ill. Viruses produce inside body cells. They reproduce inside and burst out destroying it. They then invade other cells.

Our white blood cells help defend against these. They're called Phagocytes and Lymphocytes.
Phagocytes suround and ingest the pathogens. Whereas Lymphocytes produce antibodies to destroy pathogens and produce antitoxins that neutralise the toxins that are released by pathogens. The antibodies and antitoxins have to be right kind. They can produce the right kind quicker if they have already come across that kind of pahogen in the past and remember its antigens on its surface.

A person becomes immune to a disease when they've already come across the same pathogen and remember its antigens. This means they can reproduce the right type of antigen quicker and therefore kill the pathogen quicker.

Semmelweiss was horrified by the number of women who died after a trouble-free birth. They died within a few weeks with puerperal fever but nobody knew about bacteria and viruses back then. A proffesor accidently got cut with a knife. He died within a few days with the same symptoms as the women. Semmelweiss thought that something might have transferred to his hand from the bodies.

Semmelweiss then made all the doctors wash their hands in chlorine water before examining the women. The death rate decreased.

Wash our hands regulary.

Painkillers are used to reduce the symptoms of a illness whereas antibiotics can kill most bacteria without damaging cells. They cannot kill viruses though, as viruses produce inside the cell.

Antibiotics are only used unless its necessary to make sure that no mutations happen within the DNA of the bacterium.  So that if they do, they will not reproduce and become resistant to a antibiotic.