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NON SPECIFIC RESPONSE TO DISEASE
1)Define the term ‘immune response’
2) Describe the primary defences in place
against pathogens
3) Describe the structure of phagocytes and
explain how they work
NON SPECIFIC DEFENCE MECHANISMS
The body has a range of defences to protect it
against disease causing organisms, or
pathogens.
 Make notes on the body outline to show these
defences.

PHAGOCYTES – SECONDARY RESPONSE
Pathogens which manage to enter the body must
be killed before they reproduce. And cause
disease.
 This job is done by phagocytes & there are 2 types
1) Neutrophils - most common. Made in bone
marrow and travel in our blood. Do not live for
long but are released in large numbers if an
infection is detected.
2) Macrophages – also made in bone marrow. Settle
in body organs and develop into macrophages.

HOW PHAGOCYTES WORK
Their role is to engulf and destroy pathogens.
Step 1 - When the pathogen enters, our body realises it is
foreign because it has markers on its outer membrane.
These markers are Antigens.
(Our own cells have these but our body recognises that
they are our own and not a threat)
Step 2 - Antibodies in our blood attach to the foreign
antigens and the receptors on the phagocytes bind to
the antibodies.
Step 3 – As the phagocyte is now attached it will envelop
the pathogen. Lysosomes now fuse to it and release
enzymes which digest it.
Step 4 – The digested invader is now harmless and
released into the cytoplasm.
TASK
 Create
a short video, using the flip
cams, to show the action of
phagocytosis.
 Explain why people who sustain burns
often die from infections.
 Explain why the area around a wound
often looks red.