AS BIOLOGY

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Pathogens

microorganisms which are harmful. Include bacteria, fungi and viruses. Must cause infection. Enter the body by penetrating one of the organisms interfaces. Do this by gas exchange surfaces or digestive system (food and drink passed via mouth) - carry pathogens into stomach and intestines.

causes disease by

- damaging host tissues, prevent the tissues from functioning properly. Break down membranes of the host cells

- producing toxins (cholera bacterium produces a toxin causing lots of water loss from lining of intestines) bacterial pathogens produce toxins.

infection - when a pathogen gets into a host and colonizes its tissues.

Disease - when a infection leads to recognizable symptoms in the host

Transmission - when a pathogen is transferred from one individual to another.

Cause of Disease - Lifestyle and

correlation - when a change in one of two variables is reflected by a change in other variable

causal link - when there is evidence to prove it between the cause and the result

Risk - a measure of the probability that damage to health will occur as a result of a given hazard, can be measured as a value that ranges from 0% to 100%

age and genetics affect the risk of contracting cancers.

CHD Factors:

ones we can control;

- Smoking, High blood pressure, blood cholesterol levels, obesity, diet and physical activity

ones we can't control;

- Genes, age and sex

We can reduce the risk of cancer and CHD:

- not smoking

- avoid becoming overweight

- reduce salt in diet

- reduce intake of cholesterol and saturated fats

- regular aerobic exercise

- keep alcohol consumption within safe limits

- increase the intake of dietary fiber and antioxidants

Human Digestion

food moves down the gullet.

Physical digestion - chewing of the food, tongue pushes the food to the back of the mouth.

Chemical digestion - breaks down large, insoluble molecules into smaller, soluble ones. Carried out by enzymes and function by hydrolysis (splitting up of molecules by adding water to the chemical bonds that hold them together)

Carbohydrases - break down carbohydrates, ultimately to monosacchrides

Lipases - break down lipids (fats and oils) into glycerol and fatty acids

Proteases - break down proteins, ultimately to amino acids 

Body parts of digestion:

  • mouth
  • gullet
  • stomach

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