They are micro-organisms
that cause disease, there
are 4 different types
Protozoa (e.g.
dysentery)
Viruses (e.g. Flu)
Bacteria (e.g.
cholera)
Fungi (e.g.
athlete's foot)
Malaria
It is caused by a protozoan,
this protozoan is a parasite
It is carried by mosquitoes,
they are vectors
Vectors can
carry the disease
without getting it
themselves
Preventing
Mosquito nets
Fish can be
introduced to eat
mosquito larvae
Places that
mosquito's go
can be sprayed
with insecticides
Immune system
Once inside your
body, pathogens
reproduce rapidly
White blood cells
have the job of
destroying them,
they constantly
patrol your body
Lines of attack
1) Consuming - they
engulf foreign cells
and digest them
2) Producing antitoxins
- they counter the
effects of any poisons
3) Producing
antibodies - each
pathogen has unique
molecules on the top,
these are called
antigens, when the
white blood cells
come across an
antigen, they produce
a specially designed
antibody to kill it
The antibodies are then
produced rapidly and flow
around the body to kill the
rest off
Some memory cells
stick around so that if
the person is infected
again they can
instantly kill it off
Preventing and treating
Antibiotics
They are drugs that kill off
bacteria without killing body cells
They can't kill viruses
Antivirals treat viral
infections, they stop
viruses from reproducing
Some bacteria are naturally
resistant to antibiotics (e.g.
MRSA)
Immunisation
Risks
Can cause short
term effects like...
Swelling and redness at
the injection site
Feeling a bit under
the weather
You can't have vaccines if you are
already ill because you immune
system is weak
People think that immunisation can cause
other disorders (e.g. some people think there
is a link between the MMR vaccine and autism
Benifits
Stops the disease from
spreading easily
It stops you from getting ill
You can get very ill and
even die from pathogens
To avoid this, you
can be immunised
It involves injecting dead or
inactive pathogens into the body
Your white blood cells
produce antibodies to
attack them
Some of these memory
cells will stick around to kill
off the disease if you get it
Active immunity is
where the immune
system makes it's own
antibodies after being
stimulated by a pathogen
Passive immunity
is when
antibodies are
made by another
organism,
passive immunity
is only temporary
Cancer
Tumors
Benign - the tumour grows
until it runs out of room, it
stays in the same place, it
isn't normally dangerous
Malignant - the tumour
grows and can spread
to other parts of the
body, they are very
dangerous and can be
fatal
Reduce your risk
Not smoking reduces your
risk of getting lung cancer
Eating less processed
meat and more fibre
can reduce the risk of
colon cancer
Drugs
New drugs must be
tested before they are
given to human
1) Computer models
simulate the reaction of a
human to the drug, promising
one's go onto the next stage
2) The drugs are then
tested on human tissues,
again promising one's go
onto the next stage
3) The law states that
new drugs must be
tested on at least two
different live mammals
4) It is then tested on humans,
this is called a clinical trial, in
the trial, there are two groups
of patients, one gets the new
drug, the other get a placebo
(it doesn't do anything) or the
best existing treatment
Drugs
Beneficial and harmful
Drugs change
the way our
bodies work,
they can be
very dangerous,
this is why you
can only get
some drugs on
perscription
Some people get
addicted to drugs and
get withdrawal
symptoms if they don't
have it
Tolerance develops with
some drugs, this means you
get used to having it and
have to have a higher dose
to get the same effect
If someone is
addicted,
rehabilitation
can help
Types
Depressants
(e.g. alcohol,
temazepam
They decrease the
activity of the brain,
causing slow reactions
and poor judgement of
speed and distance
Stimulants (e.g.
nicotine, caffeine)
Opposite of
depressants, they
increase the activity
of the brain, it is
sometimes used to
treat depression
Painkillers (e.g.
aspirin, paracetamol)
They work by
reducing the
amount of painful
stimuli at nerve
endings
Performance
enhancers (e.g.
anabolic steroids
Sometimes
taken by
athletes, they
help build
muscle
Hallucinogens
(e.g. LSD)
They distort what's seen and
heard and heard by altering
the pathways that the brain
sends messages along
Illegal
Categorised into three
categories, class A is
the most dangerous