Interactions With the Environment: Lifestyle and Health — AQA Combined Science: Synergy
This topic covers health and disease, risk factors, cardiovascular disease, homeostasis, diabetes and human reproductive hormones.
Health and disease
Health is a state of physical and mental wellbeing. Diseases are a major cause of ill health. Communicable diseases can be spread; non-communicable diseases (e.g. cardiovascular disease, many cancers) cannot. Different diseases can interact — for example a weakened immune system increases the risk of communicable disease.
Risk factors for non-communicable diseases
A risk factor is something linked to an increased rate of a disease. Examples: smoking, poor diet, lack of exercise, obesity, alcohol and ionising radiation. Be careful to distinguish correlation from a proven causal mechanism. Lifestyle, financial and emotional effects of non-communicable disease are felt by individuals and society.
Cardiovascular disease and its treatment
In coronary heart disease, fatty deposits narrow the coronary arteries, reducing blood flow to the heart muscle. Treatments:
- Stents keep arteries open.
- Statins reduce blood cholesterol, slowing fatty build-up.
- Faulty valves can be replaced; severe heart failure may need a transplant or artificial heart.
You should be able to evaluate these treatments.
Homeostasis
Homeostasis maintains stable internal conditions for cells to function, using receptors, coordination centres and effectors, often through negative feedback.
Insulin and diabetes
The pancreas controls blood glucose:
- High glucose → insulin released → cells take up glucose, stored as glycogen.
- Low glucose → glucagon released → glycogen converted back to glucose.
Type 1 diabetes — little/no insulin produced; treated with insulin injections. Type 2 diabetes — cells stop responding to insulin; linked to obesity; treated with diet and exercise.
Human reproductive hormones
At puberty sex hormones cause secondary sexual characteristics. Testosterone (testes) stimulates sperm production; oestrogen (ovaries) is the main female hormone.
The menstrual cycle
- FSH — matures an egg.
- Oestrogen — builds the uterus lining.
- LH — triggers ovulation.
- Progesterone — maintains the lining.
Contraception
- Hormonal: the pill, implants, injections (stop eggs maturing). Effective but possible side effects.
- Non-hormonal: condoms and diaphragms (barrier, also prevent STIs), IUDs, abstinence and sterilisation.
You should be able to evaluate the methods.
Treatments for infertility (Higher Tier)
Fertility can be increased using hormones (e.g. FSH and LH as a "fertility drug") and by IVF (in vitro fertilisation), where eggs are fertilised outside the body and implanted. IVF is emotionally and physically demanding, has low success rates and raises ethical issues.
Exam tips
- Distinguish correlation from a proven causal risk factor.
- Insulin lowers blood glucose; glucagon raises it.
- Compare Type 1 and Type 2 diabetes (cause and treatment).
- Learn the four menstrual-cycle hormones and their roles.
- Be ready to evaluate CHD treatments, contraception and IVF.