Disease

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
• Understand that a pathogen may be transmitted: (a) through direct contact, including through blood or other body fluids (b) indirectly, including from contaminated surfaces or food, from animals, or from the air
• Describe the human body’s barriers to the entry of pathogens, limited to: skin, hairs in the nose, mucus, stomach acid
• Understand the role of the mosquito as a vector of disease
• Describe the malarial pathogen as an example of a parasite and explain how it is transmitted
• Describe the control of the mosquito that transmits malaria with reference to its life cycle
• Explain that human immunodeficiency virus (HIV) is a viral pathogen
• Describe how HIV is transmitted
• Understand that HIV infection may lead to Acquired Immune Deficiency Syndrome (AIDS)
• Describe the methods by which HIV may be controlled
• Describe cholera as a disease caused by a bacterium, which is transmitted in contaminated water
• Explain the importance of a clean water supply, hygienic food preparation, good personal hygiene, waste disposal and sewage treatment in controlling the spread of cholera (details of the stages of sewage treatment are not required)
• 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, resulting in diarrhoea, dehydration and loss of ions from the blood
• Describe the effects of excessive consumption of alcohol: reduced self-control, depressant, effect on reaction times, damage to liver and social implications
• Describe the effects of tobacco smoke and its major toxic components (nicotine, tar and carbon monoxide): strong association with bronchitis, emphysema, lung cancer, heart disease, and the association between smoking during pregnancy and reduced birth weight of the baby