BiologyCode 5090
Disease
What this topic asks you to be able to do
- Outline a pathogen as an organism that causes disease
- Describe a transmissible disease as one whose pathogen can spread from host to host
- Understand the ways a pathogen may be transmitted: by direct contact, including via blood or other body fluids; by indirect contact, including from contaminated food or surfaces; from animals; and from the air
- Outline the barriers that keep pathogens out of the human body, limited to: skin, hairs in the nose, mucus, stomach acid
- Understand how the mosquito acts as a vector that spreads disease
- Describe the malarial pathogen, using it to show what a parasite is, and explain how it is transmitted
- Describe how the mosquito that transmits malaria can be controlled, using what is known about its life cycle
- Explain that human immunodeficiency virus (HIV) belongs to the category of viral pathogens
- Outline the ways HIV gets transmitted
- Understand that an HIV infection can progress to Acquired Immune Deficiency Syndrome (AIDS)
- Outline the methods that can be used to control HIV
- Describe cholera as a bacterial disease, transmitted through water that is contaminated
- Explain why a clean water supply, hygienic preparation of food, good personal hygiene, waste disposal and sewage treatment matter in controlling cholera's spread (the stages of sewage treatment need not be detailed)
- Explain that the cholera bacterium releases a toxin which makes the small intestine secrete chloride ions, so that water moves into the gut by osmosis, leading to diarrhoea, dehydration and ions being lost from the blood
- Outline what happens when alcohol is consumed to excess: lowered self-control, acting as a depressant, impact on reaction times, damage to liver and social implications
- Describe the effects on health of tobacco smoke and of its major toxic components (carbon monoxide, nicotine and tar): a strong association between smoking and bronchitis, emphysema, lung cancer and heart disease, and an association between smoking in pregnancy and the baby having a reduced birth weight