2. LO:
• Define the key words:
– Pathogen
– Transmissible disease
– Active immunity
– Passive immunity
• Explain the process of vaccination
• Explain the specificity of antigens
• State the types of body defence
4. Transmissible disease
• Is a disease in which the pathogen can be
passed from one host to another
Diseases can be transmitted:
• direct contact, e.g. through blood or other
body fluids,
• indirectly, e.g. from contaminated surfaces or
food, from animals, or from the air
5.
6. Defence systems
• Mechanical barriers:
- skin and hairs in the nose
• Chemical barriers:
– mucus and stomach acid
• Cells:
– phagocytosis and antibody production by white
blood cells
can be enhanced by vaccination
7.
8. • Discuss the importance of:
– hygienic food preparation,
– good personal hygiene,
– waste disposal and
– sewage treatment
in controlling the spread of disease
9. White blood cells
: phagocytes, lymphocytes
– Distinguish between self and non-self cells
– Produce antibodies
• Molecules on the surfaces of cells that are not found
in other organisms = antigens (e.g. blood system)
• The response of lymphocytes to the presence of a
foreign antigen = immune response
10. • Lymphocytes
– Produce antibodies; memory cells
– antibodies lock on to antigens leading to direct
destruction of pathogens, or marking of
pathogens for destruction by phagocytes
– each pathogen has its own antigens, which have
specific shapes, so specific antibodies which fit the
specific shapes of the antigens are needed
• Phagocytes
– phagocytosis
11.
12. • Memory cells
– Remain circulating in the body for a long time
– If the same antigen is reintroduced a few weeks or
months later, memory cells divide rapidly and
develop into plasma cells
– Basis of immunological memory
– Last for many year, lifelong,
16. • Active immunity
– defence against a pathogen by antibody production in
the body
– is gained after an infection by a pathogen, or by
vaccination
• Passive immunity
– short-term defence against a pathogen by antibodies
acquired from another individual, e.g. mother to
infant
– No memory cells are produced
– Important for new-borns: get all antibodies from the
mother
17. Vaccination
process of vaccination:
• harmless pathogen given which has antigens
• antigens trigger an immune response by
lymphocytes which produce antibodies
• memory cells are produced that give long-
term immunity
18. Autoimmune diseases
• some diseases are caused by the immune
system targeting and destroying body cells
• Type 1 diabetes
