Transcript Natural Barriers - Trinity School Nottingham

Keeping Healthy Revision
Natural Barriers
Skin
Sweat
Tears
Stomach
acid
Infection
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Micro-organisms increase in numbers
rapidly.
The symptoms of a disease are caused
by the micro organisms or their toxins.
The body has an immune system to
fight infection.
White Blood Cells
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Some white blood cells ‘eat’ invading
micro organisms (phagocytosis).
Some white blood cells produce
antibodies that stick to invading micro
organisms.
Each antibody will be specific to a
particular micro organism eg chicken
pox.
Once produced, the white blood cells
remember the micro organism and kill
Vaccines
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Vaccines inject a small amount of ‘safe’ micro
organisms causing the body to produce antibodies.
The White blood cells remember the ‘safe’ version
and attack the disease causing micro organism
when it invades giving immunity.
Vaccines can produce side effects in some and so
are never totally safe.
Some micro organisms (eg influenza, HIV) mutate
(change) so quickly that the antibodies don’t
recognise them. This makes it difficult to get
immunity
Some organisms eg AIDS damage the immune
system making it difficult to get immunity.
Vaccination (cont)
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Need a lot of people to be vaccinated
to prevent epidemics (herd immunity).
Some people may not wish to risk the
side effects (MMR). This may prevent
herd immunity being achieved.
Antibiotics
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Antibiotics kill bacteria but not fungi or
viruses.
Bacteria can mutate and become
resistant to the antibiotic.
We should therefore only use
antibiotics when necessary and
complete the course.
The resistant bacteria will survive
better if we take too many antibiotics
and kill all the competition
Drug Testing
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New drugs must be tested to make
sure they are safe and effective.
This may involve animal trials.
Human trials involve ‘blind’ and
‘double blind’ trials, and placebos.
Ethical issues are involved with respect
to animal testing and selecting people
for trials.
Heart Disease
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Very common in the UK and
industrialised countries.
Is caused by a build up of fatty
deposits in the coronary arteries.
Lifestyle factors such as poor diet,
smoking, stress and alcohol increase
the chances of heat disease.
Regular, but not excessive, exercise
reduces the chance of heart disease.
Analysing Data
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Distinguish between correlation and
cause.
Assess critically whether studies are
reliable.
Describe the relationship between 2
factors on a graph, such as increase,
decrease, steady, uniform and
proportional.