What you need to know
- 1.12Genetics, diet, age, gender, high blood pressureThe pressure that blood exerts on the walls of the blood vessels., smoking and inactivity as CVD risk factorSomething that increases the probability of developing a disease, without making it certain..
- 1.19Using knowledge of exercise and smoking to reduce coronary heart disease risk.
By the end, you should be able to…
- Explain mechanisms connecting major risk factors to CVD.
- Distinguish modifiable and non-modifiable factors.
- Explain why several risk factors must be considered together.
Build your understanding
Risk factors work through different routes
Inherited variants can affect lipid metabolism and blood cholesterolA lipid found in cell membranes. High levels of LDL cholesterol in the blood are a risk factor for atheroma.. Family history can reflect both inherited factors and shared environments. Increasing age is associated with longer cumulative exposure to risk factorSomething that increases the probability of developing a disease, without making it certain. and changes in vessels, so comparisons should account for age.
The specification uses “gender”. Biological sex-related factors and social or behaviouralDescribes an adaptation of the way an organism acts, such as migration or courtship. factors can both influence observed patterns; group differences do not establish a single mechanism or predict every individual. Describe the categories and evidence supplied rather than assuming all people in a category have the same risk.
Pressure and smoking
Persistently high arterial pressure increases mechanical stress on vessel walls and can contribute to endothelial dysfunction. Damage and atherosclerosisThe hardening and narrowing of arteries caused by atheromas building up in their walls. may further impair vessel function. Connect this to the plaque development studied in 1B.
Components of tobacco smoke promote endothelial injury and clot formation. Nicotine stimulates responses that increase heart rateThe number of heartbeats per minute. and can raise blood pressureThe pressure that blood exerts on the walls of the blood vessels.; carbon monoxide binds haemoglobinA globular protein in red blood cells with four polypeptide chains, each with a haem group containing Fe²⁺ that binds one O₂., reducing oxygen transport. Smoking therefore acts through several mechanisms, not simply by making someone less fit.
Activity, diet and combined risk
Physical inactivity is associated with poorer cardiovascular fitness and can contribute to excess body fat and raised blood pressure. Regular activity can improve fitness and help manage these factors. Diet can influence energy balance, blood lipids and pressure; its mechanisms are developed in the next lesson.
Some factors can be modified, such as smoking or inactivity; others, such as age or inherited variants, cannot be changed. Modifying one factor may still reduce risk when others remain. Risk factors can interact, so do not add or multiply relative risks unless a supplied model justifies it.
Follow the process
Smoking is not one straight line. Branch 1: smoke components injure endotheliumThe single layer of flat cells that lines the inside of blood vessels and the heart. → the wall is more likely to form an atheromaA fatty plaque of cholesterol, white blood cells and fibrous tissue that builds up under the endothelium of an artery. and to trigger clotting → a coronary arteryA vessel that carries blood away from the heart at high pressure. It has a thick wall with elastic fibres and smooth muscle. may narrow or block → heart muscle receives less oxygen. Branch 2: nicotine can raise heart rate and blood pressure. Branch 3: carbon monoxide binds haemoglobin → less oxygen is carried.
Write X because Y, leading to Z for the branch the question asks about. X: risk of a coronary blockage rises. Y: endothelial injury makes atheroma and thrombosis more likely. Z: heart muscle may be starved of oxygen. Do not write “because smoking is unhealthy”: that repeats the exposure and gives no mechanism. Quote a supplied figure with its units when you use data to support a trend.
Make your reasoning visible
Build the explanation
Incomplete: “High blood pressureThe pressure that blood exerts on the walls of the blood vessels. causes heart disease.” Improved: “High arterial pressure increases mechanical stress on the endotheliumThe single layer of flat cells that lines the inside of blood vessels and the heart., which can start the inflammatory and lipid changes that build an atheromaA fatty plaque of cholesterol, white blood cells and fibrous tissue that builds up under the endothelium of an artery..” The improvement names the structure and the next biological change. A factor raises probability; it does not guarantee disease in every person.
Use probabilistic language
A factor increases the chance of disease; it does not mean everyone exposed develops it or everyone unexposed is protected.
Avoid this misconception
The claim: An inherited risk means lifestyle changes cannot help.
The correction: Inherited risk does not remove the influence of modifiable factors. Their relative contributions depend on the person and evidence.
Check your understanding
Try each question before opening the suggested answer.
Practice question
Retrieval and explanation · suggested answer
Explain how high blood pressure can contribute to atherosclerosis.
Show suggested answer
Greater mechanical stress can impair the endothelium, encouraging inflammatory and lipid-accumulation processes in the artery wall that contribute to plaque formation.
Practice question
Retrieval and explanation · suggested answer
Why is one long-lived smoker insufficient evidence that smoking does not increase CVD risk?
Show suggested answer
Risk describes probabilities across comparable groups. An individual exception can occur even when exposure increases the overall probability of disease.
Take the idea further
Apply the same specification knowledge to an unfamiliar problem. Any extra assumptions are supplied in the question.
Stretch question
A smoking group has more CVD than a non-smoking group but is also older. What should researchers do before attributing the entire difference to smoking?
Show a hint
Identify a possible confounder.
Explore the reasoning
Compare age-matched groups or adjust appropriately for age and other measured confounders. This improves the comparison, though unmeasured confounding may remain. Independent mechanistic and intervention evidence can strengthen the causal case.
Recall this lesson
Lesson recall questions
Question 1 of 5: Explain, in causal order, how smoking can increase CVD risk.
CVD risk factors
Practice question
Retrieval and explanation · suggested answer
Explain, in causal order, how smoking can increase CVD risk.
Lesson: 1C 3: Risk Factors for Cardiovascular Disease
Build the sequence from memory first. Then reveal the model order.
Tap the steps in the order you recall. Tap a placed step to send it back.
- 01Next step
- 02Waiting
- 03Waiting
Tap to place
Put your biology to work
Explore where these ideas appear in the world. Enrichment, not extra required recall.
Why a warning needs more than a slogan
1C · Risk Factors for Cardiovascular DiseaseCDC identifies smoking as a cause of cardiovascular disease and describes effects on blood vessels and clotting. Public-health communication can connect this evidence to mechanisms rather than relying…Specification 1.12Read & use the scienceClose article
Why this matters
CDC identifies smoking as a cause of cardiovascular disease and describes effects on blood vessels and clotting. Public-health communication can connect this evidence to mechanisms rather than relying only on frightening images. For example, explaining how carbon monoxide reduces oxygen-carrying capacity gives a warning a biological chain rather than only an alarming image. Nicotine, carbon monoxide and other smoke components have different effects, so the message should identify the relevant substance. A public-health scientist also needs evidence about whether the message changes behaviour and who it reaches. A scientifically accurate mechanism and an effective intervention are related questions, but success at one does not automatically demonstrate success at the other.
Back to the specification
Pearson Edexcel IAL Biology · Issue 2, February 2021 · Unit 1, pp. 15–18. The application extends beyond required recall.
- 1.12 know how factors such as genetics, diet, age, gender, high blood pressure, smoking and inactivity increase the risk of cardiovascular disease (CVD)
Use the science
A warning says carbon monoxide makes the heart work harder. Explain a biological chain connecting carbon monoxide exposure with oxygen supply, and why that mechanism alone does not prove the warning changes behaviour.
Explore a possible response
Carbon monoxide binds strongly to haemoglobin, reducing its oxygen-carrying capacity. Less oxygen can be delivered for a given blood flow, potentially increasing the demand on circulation. To show the message changes behaviour, researchers must measure behaviour using a suitable comparison; knowing the mechanism is not evidence of that communication outcome.
Explore the source
A heatwave is also a cardiovascular event
1C · Risk Factors for Cardiovascular DiseaseHot weather can place extra demands on the cardiovascular system. The CDC describes how heat stress, dehydration and changes in clotting risk can contribute to cardiovascular problems, particularly…Specification 1.6 · 1.12 · 1.15Read & use the scienceClose article
Why this matters
Hot weather can place extra demands on the cardiovascular system. The CDC describes how heat stress, dehydration and changes in clotting risk can contribute to cardiovascular problems, particularly in people with existing disease. This expands the familiar list of lifestyle and inherited risks to include environmental conditions. The transport system must keep supplying tissues while the body responds to heat, and people differ in their capacity to cope. Studying hospital admissions during a heatwave also requires care: age, existing illness, air pollution and access to cooling can all affect the observed pattern. Exposure is not distributed equally across a population.
Back to the specification
Pearson Edexcel IAL Biology · Issue 2, February 2021 · Unit 1, pp. 15–18. The application extends beyond required recall.
- 1.6 understand why many animals have a heart and circulation (mass transport to overcome the limitations of diffusion in meeting the requirements of organisms)
- 1.12 know how factors such as genetics, diet, age, gender, high blood pressure, smoking and inactivity increase the risk of cardiovascular disease (CVD)
- 1.15 be able to analyse and interpret quantitative data on illness and mortality rates to determine health risks, including distinguishing between correlation and causation and recognising conflicting evidence
Use the science
Why would a higher death count on hot days alone be insufficient to calculate how much heat increases an individual’s cardiovascular risk?
Explore a possible response
Counts need denominators and comparable populations, while pollution, age, illness and other factors may confound the association. Individual baseline risk varies.