Lifestyle & Disease

Lifestyle & Disease 🫀

Not every illness is caught from someone else. Many of the biggest killers build up **inside** us over years — shaped by how we live. This module: what goes wrong in the heart, what a "risk factor" really means, and how cancer spreads.

A clogging heart 🩹

In **coronary heart disease (CHD)**, fatty material builds up inside the **coronary arteries**, narrowing them so less blood — and less **oxygen** — reaches the heart muscle. Doctors have several fixes: **stents** (tubes that hold the artery open), **statins** (drugs that lower blood cholesterol), replacement heart **valves**, and even **artificial hearts**.

Treating the patient

An interactive activity.

What each fix does

Two families of disease 🦠

Diseases fall into two groups: • **Communicable** — caused by **pathogens** and can **spread** from person to person (measles, flu). • **Non-communicable** — **cannot** be spread; they build up over time (heart disease, cancer, type-2 diabetes). A **risk factor** is anything linked to an **increased probability** of a disease.

Which kind?

Coronary heart disease cannot be passed from one person to another. What type of disease is it?

• Non-communicable
• Communicable
• Infectious
• Viral

How lifestyle plays in 🚬

Lifestyle choices raise the risk of non-communicable disease: a poor **diet** and **inactivity** (type-2 diabetes, heart disease), **smoking** (lung disease, cancer) and **alcohol** (liver and brain damage). But be careful with evidence: a risk factor **correlates** with a disease — it raises the probability — but correlation alone doesn't prove it **causes** it. A **causal mechanism** must be shown.

Read the evidence

A graph shows that people who smoke more cigarettes have higher rates of lung cancer. What can you correctly conclude?

• Smoking is a risk factor for lung cancer — it increases the probability
• This proves smoking directly causes every case of lung cancer
• Smoking has no effect on lung cancer
• Only smokers ever get lung cancer

Spot the risk factors

Pick the THREE lifestyle risk factors for non-communicable disease.

• Smoking
• A poor diet
• Lack of exercise
• Catching a cold from a friend
• Being tall

Cancer 🎗️

**Cancer** is the result of **uncontrolled** cell growth and division, forming a **tumour**. There are two kinds: • **Benign** tumours grow in **one place** and don't invade other tissues — usually not dangerous. • **Malignant** tumours are cancerous: they **invade** neighbouring tissues and **spread** in the blood to form **secondary tumours** elsewhere — dangerous.

The dangerous kind

What makes a **malignant** tumour more dangerous than a benign one?

• Its cells invade other tissues and spread in the blood to form secondary tumours
• It is always physically larger
• It is only found in older people
• It is always painful

In the exam 🎓

Well diagnosed. Grade-9 habits for health and disease: • Match the **treatment** to the problem: stents open arteries, statins lower cholesterol, artificial hearts buy time. • Say **risk factor** (increases probability), not "cause" — weigh correlational evidence, don't over-claim. • **Benign** tumours stay in one place; **malignant** ones invade and spread (secondary tumours).