10 Diseases and Immunity

10 Diseases and Immunity
Diseases and Immunity
1. Describe a pathogen as a disease-causing organism.
2. Describe a transmissible disease as a disease in which the pathogen can be passed from one host to another.
3. State that a pathogen is transmitted:
▪ By direct contact, including through blood and other body fluids.
▪ Indirectly, including from contaminated surfaces, food, animals, and air.
4. Describe the body defences, limited to: skin, hairs in the nose, mucus, stomach acid, and white blood cells.
5. Explain the importance of the following in controlling the spread of disease:
▪ A clean water supply.
▪ Hygienic food preparation.
▪ Good personal hygiene.
▪ Waste disposal.
▪ Sewage treatment (details of the stages of sewage treatment are not required).
6. Describe active immunity as defence against a pathogen by antibody production in the body.
7. State that each pathogen has its own antigens, which have specific shapes.
8. Describe antibodies as proteins that bind to antigens leading to direct destruction of pathogens or marking of pathogens for destruction by phagocytes.
9. State that specific antibodies have complementary shapes which fit specific antigens.
10. Explain that active immunity is gained after an infection by a pathogen or by vaccination.
11. Outline the process of vaccination:
▪ Weakened pathogens or their antigens are put into the body.
▪ The antigens stimulate an immune response by lymphocytes which produce antibodies.
▪ Memory cells are produced that give long-term immunity.
12. Explain the role of vaccination in controlling the spread of diseases.
13. Explain that passive immunity is a short-term defence against a pathogen by antibodies acquired from another individual, including across the placenta and in breast milk.
14. Explain the importance of breastfeeding for the development of passive immunity in infants.
15. State that memory cells are not produced in passive immunity.
16. Describe cholera as a disease caused by a bacterium which is transmitted in contaminated water.
17. Explain that the cholera bacterium produces a toxin that causes secretion of chloride ions into the small intestine, causing osmotic movement of water into the gut, causing diarrhoea, dehydration, and loss of ions from the blood.