Diseases and immunity

What the syllabus asks of you

• Describe a pathogen as a disease-causing organism
• Describe a transmissible disease as a disease in which the pathogen can be passed from one host to another
• State that a pathogen is transmitted: (a) by direct contact, including through blood and other body fluids (b) indirectly, including from contaminated surfaces, food, animals and air
• Describe the body defences, limited to: skin, 6 Describe active immunity as defence against a hairs in the nose, mucus, stomach acid and pathogen by antibody production in the body white blood cells 7 State that each pathogen has its own antigens,
• Explain the importance of the following in which have specific shapes controlling the spread of disease: 8 Describe antibodies as proteins that bind (a) a clean water supply to antigens leading to direct destruction (b) hygienic food preparation of pathogens or marking of pathogens for (c) good personal hygiene destruction by phagocytes (d) waste disposal (e) sewage treatment (details of the stages of sewage treatment are not required) 9 10 Explain that active immunity is gained after an State that specific antibodies have complementary shapes which fit specific antigens infection by a pathogen or by vaccination 11 Outline the process of vaccination: (a) weakened pathogens or their antigens are put into the body (b) the antigens stimulate an immune response by lymphocytes which produce antibodies (c) 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 breast-feeding for the development of passive immunity in infants 15 State that memory cells are not produced in passive immunity continued Core Supplement 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