2. A disease causing organism
For a microorganism to be considered a
pathogen it must:
1) Gain entry to the host
2) Colonise tissues of the host
3) Resist defences of the host
4) Cause damage to host tissues
Types of pathogens are: bacteria, viruses and
fungi.
3. Infection - When a pathogen gains entry and
colonises tissue.
Disease - recognisable symptoms of the
infection.
Transmission - Spreading of the pathogen
Interface - surface or boundary linking two
systems.
4. 1. Skin:
* thick, continuous layer.
* effective barrier.
* invasion occurs when skin is broken
2. Exchange sites:
* Gas-exchange
* Digestive system
- body linings at exchange systems are thin,
moist, sticky, have a large surface area and
well equipped with blood vessels.
5. Mucous layer covering exchange surfaces,
forming a sticky thick barrier- difficult to
penetrate
Production of Enzymes to break down
pathogens
Production of stomach acid to kill
microorganisms.
6. Damaging host tissues:
- sheer number can prevent tissues
functioning properly.
- Viruses inhibit synthesis of DNA, RNA and
proteins.
- Pathogens may break down membranes of
host cells.
Producing toxins:
-Bacterial pathogens
Time taken to cause damage depends on how
rapidly pathogen divides.
7. A Correlation occurs when a change in one
variable reflects a change in the other
variable.
A Causal Link is a change in one variable
which results from a change in another
variable.
A Correlation does NOT mean there is a
causal link. Experimental Evidence is
needed.
8. Risk – A measure of the probability that
damage to health will occur as a result of a
given hazard.
Relative Risk – comparing the likelihood of
harm occurring in those exposed to a hazard
to those who are not. E.g. Lung cancer in
smokers and non-smokers.
9. Factors we can control include:
- Smoking – smokers and passive smokers
- Diet – low fat, high fibre, rich in fruit and
veg reduces risk of cancer.
- Obesity – overweight increases risk
- Physical Activity – exercising regularly
decreases risk.
- Sunlight – more exposed = greater rik
10. Smoking – 2 and 6 times more likely to suffer.
High blood pressure – excessive stress,
certain diets and lack of exercise increase
blood pressure and risk.
Blood cholesterol levels – keep low by
consuming less saturated fats
Obesity – bmi of over 25 increases risk
Diet – high levels of salt increase risk
Physical Activity – Aerobic exercise lowers
blood pressure and cholesterol reducing risk.
Heredity
11. Give up smoking – single most effective way
Avoid becoming overweight
Reduce salt intake
Reduce saturated fat and cholesterol intake
Regular aerobic exercise
Consume alcohol safely
Include intake of dietary fibre and
antioxidants
