2.7.4Additional lessons
Coronary Heart Disease — IB Biology SL Revision Notes & Topical Questions
5 min read 6 parts Lesson 37 of 142
Curriculum Equation Key قوانين الرقم الهيدروجيني والاتزان الأيوني - pH & Acid-Base Equilibrium FormulasFast Exam Solution
pH = -log[H⁺] | pOH = -log[OH⁻] | pH + pOH = 14 | [H⁺][OH⁻] = 10⁻¹⁴
Word Equation & Conditions: الرقم الهيدروجيني = -لوغاريتم تركيز أيون الهيدروجين | pH + pOH = 14
Location & Specifications: الاتزان الأيوني، كيمياء 3 ثانوي، التحصيلي، و AP Chemistry.
Part 1 of 6Coronary Arteries and Atherosclerosis
Coronary arteries
- Coronary arteries These vessels branch from the aorta and supply the cardiac muscle itself with oxygen and glucose.
Plaque
- Plaque Fatty deposits containing cholesterol build up under the endothelium of an artery wall and form plaques.
Narrowing
- Narrowing Plaques thicken the wall, narrow the lumen and reduce the flow of blood through the artery.
Clot formation
- Clot formation If a plaque ruptures, a blood clot can form and block the artery completely.
Oxygen shortage
- Oxygen shortage Cardiac muscle supplied by a blocked vessel lacks oxygen and respires less, and the cells may die.
Part 2 of 6Consequences
1
A partly narrowed coronary artery supplies too little blood during exertion, causing chest pain called angina.
2
A clot lodging in a narrowed artery stops blood flow to part of the heart muscle.
3
The deprived region of cardiac muscle is damaged, which is a myocardial infarction or heart attack.
4
Damaged muscle contracts poorly, so the heart pumps less blood and may stop beating effectively.
Part 3 of 6Risk Factors and Data
Risk Factors and Data
Diet
- Diet Diets high in saturated fat and cholesterol are linked to higher blood cholesterol and greater plaque formation.
Smoking
- Smoking Chemicals in tobacco smoke damage the artery lining and raise blood pressure.
Blood pressure
- Blood pressure Hypertension damages the endothelium, which makes plaque deposits more likely.
Other factors
- Other factors Inactivity, obesity, diabetes, older age, being male and a family history all increase the risk.
Correlation
- Correlation A correlation between a factor and disease does not prove cause;
- a mechanism and controlled evidence are also needed.
Part 4 of 6Prevention and Treatment
Prevention and Treatment
Lifestyle
- Lifestyle Eating less saturated fat, stopping smoking and taking regular exercise lower the risk of coronary heart disease.
Medicine
- Medicine Drugs can lower blood pressure and blood cholesterol, which reduces the build-up of plaque in the arteries.
Surgery
- Surgery A stent can hold a narrowed coronary artery open, and bypass surgery can route blood around a blockage.
Part 5 of 6Worked Example
Question
- In a country, the incidence of coronary heart disease fell from 400 to 310 cases per 100 000 people over ten years.
- Calculate the percentage change.
- Change = 310 − 400 = −90 cases per 100 000.
- Percentage change = −90 ÷ 400 × 100 = −22.5 %.
Answer A fall of 22.5 % in incidence.
Part 6 of 6Exam Checklist & Tips
2.7.4 – Key Points for the Exam
- Atherosclerosis The build-up of fatty plaques in artery walls.
- Coronary artery An artery supplying blood to the heart muscle.
- Thrombus A blood clot formed inside a blood vessel.
- Myocardial infarction Death of an area of heart muscle caused by a blocked blood supply.
Common Mistakes
- Saying that blood in the heart chambers feeds the heart muscle;
- cardiac muscle is supplied by the coronary arteries.
- Stating that correlation proves that a risk factor causes heart disease.
- Confusing a heart attack with cardiac arrest; the first is caused by a blocked blood supply to the muscle.
- Describing plaque as being on the inside surface only, when it builds up within the artery wall.
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