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Unit 1 AQA…read more

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*Include bacteria, viruses and fungi.
*Penetrate the body via: gas exchange system, skin
and the digestive system.
*Harm the body by producing toxins and/or
damaging cells by rupturing them to release
nutrients, breaking down their nutrients and by
multiplying inside the cells.
*Molecules (usually proteins /polysaccharides)
found on the surface of cells.
*When a pathogen enters the body, the antigens
are detected as foreign which triggers the
immune response.…read more

Slide 3

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*The immune response
Lysosomes then fuse
Phagocytes recognise The phagocytes then
with the vacuole and
the antigens and secrete digestive
present the T-cells with
engulf the pathogen the antigens which
enzymes to break down
into a vacuole. activates the T-cell
the pathogen.
Some T-cells Some attach to
release the antigens on
substances to a pathogen and
activate B-cells kill the cell
B-cells are activated.
Plasma cells secrete This binding activates
They are covered in
antibodies specific to the B-cell which can
then divide via mitosis antibodies which can
the antigen. bind to antigens. (only
into plasma cells.
if complementary)
The antibodies coat the pathogen making it easier for the phagocyte to
engulf it and harder for it to enter host cells. They also neutralise the toxins
produced by the pathogen.…read more

Slide 4

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* Vaccinations contain weakened versions of pathogens.
* This causes the body to produce B-cells/memory cells
against that particular pathogen without symptoms being
experienced. We are then immune.
* Herd immunity is where most of the community has been
vaccinated which protects the minority who haven't. this
is because there are less carriers of the disease so less
people to catch it from.
*Monoclonal antibodies
* Are all identical in structure and bind to only one specific
* Monoclonal antibodies can be used for targeting cells (e.
g. caner cells as they will only bind to cancer cells so side
effects will be lower.) and tests (e.g. pregnancy tests as…read more

Slide 5

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* Cholera is a prokaryotic organism
* The toxin cholera produces causes protein channels in the small
intestines epithelial cells to open.
* This causes Cl ions to move into the lumen which also lowers the water
potential in the lumen
* Water therefore moves out of the blood, across the epithelial cells and
into the lumen to increase the water potential.
* The increase in water secretion causes diarrhoea which dehydrates the
* Oral rehydration solutions treat diarrhoeal diseases by replacing vital
nutrients lost such as: water, sugar (glucose) and salt (Chloride and…read more

Slide 6

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*The digestive system
The oesophagus- Uses waves of
muscle contraction called
PERISTALIS. Mucus is secreted to
lubricate the foods passage.
The stomach-entrance and
exit of food controlled by
sphincter muscles.
Large intestine- Absorbs
water, salts and
minerals. Small intestine- food moved
Rectum- where faeces along by peristalsis. Bile and
are stored ready for pancreatic juice neutralise
excretion. stomach acid. Soluble molecules
are absorbed into the
carbohydrase Salivary glands, pancreas, ilumen
protease Stomach, pancreas, ilumen
lipase pancreas…read more

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