Topic 4 of 8 · Form 5
Infectious diseases and immunity
Causes, transmission and prevention of cholera, malaria, tuberculosis, measles and HIV/AIDS; global distribution; antibiotics (how they act on bacteria), antibiotic resistance and its causes.
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Infectious diseases
Causes, transmission and prevention of cholera, malaria, tuberculosis, measles and HIV/AIDS; global distribution; antibiotics (how they act on bacteria), antibiotic resistance and its causes.
The immune system
- Phagocytes (neutrophils and macrophages), antigen presentation.
- B lymphocytes (plasma cells and memory cells; antibody structure and function).
- T lymphocytes (helper T cells release cytokines; killer T cells destroy infected cells).
- Primary and secondary responses.
Types of immunity
Active and passive, natural and artificial; vaccination and herd immunity; monoclonal antibodies (production and uses in diagnosis and treatment).
Autoimmune disease
Myasthenia gravis as an example.
Worked example: Explain why a second exposure to measles virus does not cause disease.
Memory cells produced in the primary response recognise the antigen, so a faster, larger secondary response destroys the virus before symptoms develop.
Check yourself
- Name the vector of malaria.
- How does penicillin kill bacteria?
- What is herd immunity?
Show answers
- Female Anopheles mosquito.
- It inhibits enzymes that build peptidoglycan cell walls, so bacteria burst by osmotic lysis.
- When enough of a population is immune, transmission is reduced and unvaccinated people are protected.
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