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Topic 3- Disease
Lifestyle and Disease
Caused by lifestyle factors such as exercise, diet, environment, drinking and smoking.
Different diseases have different risk factors.
Some risk factors are uncontrollable such as genes or age.
Some factors like diet and exercise are controllable.
Disease Risk Factors
Lung cancer Smoking, environmental pollution
Skin cancer Exposure to sunlight, colour of
Coronary heart Diet, age, genetics, exercise
Diabetes Genetics, diet, exercise
AIDs Sexual habits, drug habits,
Cause and Correlation
Epidemiology is the study of incidence, distribution and associations of diseases in order to identify their cause.
A correlation is where as one variable increases, so does another.
If there is no correlation between a variable and an outcome, then it is not a risk factor.
Even if there is correlation, the factor might not necessary be a cause- it may be coincidence or due to a third factor.
To show a causal relationship controlled laboratory experiments need to be carried out.
If the experiments show that the variable causes the outcome, then that variable is a cause.
Caused by pathogens.
Pathogens can be viruses, bacteria or fungi.
Not all bacteria are pathogens.
All viruses are pathogens.
1. The pathogen is transmitted to the host.
2. The pathogen gains entry to the body.
3. The pathogen invades the host's defences.
4. The pathogen harms the host-
By reproduction inside host cells, using resources and preventing cell reactions. The pathogens then burst out of
the cell, rupturing the membrane and killing the cell.
By producing toxins which are chemicals that interfere with the body's reactions. The chemicals can inhibit
enzymes, bind to receptors, bind to DNA causing mutations and interfere with synapses.
Fungi can decompose cells.
Endo- and Exotoxins
Endotoxin- A complex compound usually found in bacterial cell walls. The do not affect the host organism whilst they are
attached to a living bacterium. They are released when the cell dies and the cell wall breaks down, releasing the compounds.
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The toxins are picked up by macrophages causing the macrophages to release proteins that affect the body's temperature
Exotoxin- proteins that are secreted by bacteria. Each exotoxin has a different effect on the body. These exotoxins are the
cause of many symptoms of bacterial infection.…read more
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Don't have a nucleus; instead they have a nucleoid- the region of the cytoplasm containing DNA.
Don't have any membrane bound organelles; instead all metabolic reactions are carried out in areas of the cytoplasm.
Have loop DNA loose in the cytoplasm.
Have plasmids- rings of DNA that are used to exchange DNA between bacterial cells.
Ribosomes are of the smaller 70s size rather than 80s of eukaryotic cells.
Have a cell wall made of murein/ peptidoglycan.…read more
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The water potential in the lumen of the small intestine
becomes very negative so water in the cells diffuses out
The cells lose water into the lumen causing dehydration.
High water content in the lumen causes diarrhoea.
Oral rehydration therapy using oral rehydration
Rehydration solutions contain salts (Na+, Cl-, K+, Ca2+)
and glucose so that there is a lower water potential
inside the cell causing water to move into the cells and
rehydrate them.…read more