A-level Biology - 3.2.7 Heart Disease may be Associated with Specific Risk Factors
Fatty deposits (atheromas) build up in the artery walls, leading to plaque formation.
Name the 3 stages of a cardiovascular disease
Atheroma Formation
Atheroma = Aneurysm and Thrombosis
Interrupted Blood Flow to Heart = Myocardial Infarction
Key Terms
Name the 3 stages of a cardiovascular disease
Atheroma Formation
Atheroma = Aneurysm and Thrombosis
Interrupted Blood Flow to Heart = Myocardial Infarction
Describe how atheroma forms
Damage to endothelium of artery (e.g. by high blood pressure) = WBCs (mostly macrophages) and lipids from blood clump together under lining = form ...
What can the plaque (atheroma) do and cause?
Plaque blocks lumen of artery & restricts blood flow → causes blood pressure to increase
When does coronary heart disease (CHD) occur?
When coronary arteries have lots of atheromas = restricts blood flow to heart muscle
Leads to myocardial infarction
Name the 2 types of disease that affects arteries
Aneurysm
Thrombosis
What is aneurysm?
Balloon-like swelling of artery
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| Term | Definition |
|---|---|
Name the 3 stages of a cardiovascular disease | Atheroma Formation Atheroma = Aneurysm and Thrombosis Interrupted Blood Flow to Heart = Myocardial Infarction |
Describe how atheroma forms | Damage to endothelium of artery (e.g. by high blood pressure) = WBCs (mostly macrophages) and lipids from blood clump together under lining = form fatty streaks Overtime, WBCs, lipids and connective tissue build up & harden to form fibrous plaque called atheroma |
What can the plaque (atheroma) do and cause? | Plaque blocks lumen of artery & restricts blood flow → causes blood pressure to increase |
When does coronary heart disease (CHD) occur? | When coronary arteries have lots of atheromas = restricts blood flow to heart muscle Leads to myocardial infarction |
Name the 2 types of disease that affects arteries | Aneurysm Thrombosis |
What is aneurysm? | Balloon-like swelling of artery |
Describe how an aneurysm occurs | Atheroma plaques damage and weakens arteries Narrow arteries = ↑ blood pressure When blood travels through weakened artery at high pressure = pushes inner layers of artery though outer elastic layer to form balloon-like swelling = aneurysm |
What may happen to an aneurysm? | Aneurysm may burst causing bleeding |
What is thrombosis? | Formation of blood clot |
Describe how thrombosis occurs | Atheroma plaque can burst through endothelium of artery Damages artery wall & leaves rough surface Platelets and fibrin accumulate at site of damage & form blood clot (thrombus) |
Thrombosis What can the blood clot do & what can this lead to? | Blood clot can cause complete blockage of artery or can become dislodged & block blood vessel elsewhere Debris from rupture can cause another blood clot to form further down artery |
Describe how a myocardial infarction (heart attack) occurs | Coronary artery blocked = area of heart muscle cut off from blood supply, no oxygen Causes myocardial infarction (heart attack) |
What does a heart attack cause? | Damage and death of heart muscle |
What are the symptoms of a heart attack? | Pain in chest/upper body, shortness of breath and sweating |
Name 4 factors that increases the risk of cardiovascular disease | High blood pressure Smoking High blood cholesterol Poor diet |
Explain how increasing blood pressure increases the risk of cardiovascular disease | High blood pressure increases risk of damage to artery walls Damaged walls = increased risk of atheroma formation = ↑ blood pressure Atheromas = blood clots Block flow of blood to heart muscle = myocardial infarction |
Name 3 things that can increase blood pressure | Being overweight, not exercising and excessive alcohol consumption |
Describe how the nicotine from smoking can increase the risk of cardiovascular disease | Increases risk of high blood pressure |
Describe how the carbon monoxide from smoking can increase the risk of cardiovascular disease | Combines with haemoglobin and reduce amount of oxygen transported in blood Reduces amount of oxygen available to tissues If heart muscles ≠ oxygen → heart attack |
Smoking ______ the amount of _______ in blood | Smoking decreases the amount of antioxidants in blood |
Smoking Explain how decreasing the amount of antioxidants in the blood can increase the risk of cardiovascular disease | Antioxidants = important for protecting cells from damage Fewer antioxidants = cell damage in coronary artery walls more likely = atheroma formation |
Describe how high blood cholesterol can increase the risk of cardiovascular disease | Cholesterol is main constituents of fatty deposits that form atheromas Atheromas = increased blood pressure & blood clots Blocks flow of blood to coronary arteries = myocardial infarction |
Describe how a poor diet can increase the risk of cardiovascular disease | Diet high in saturated fat = high blood cholesterol levels (high LDLs) Diet high in salt = increases risk of cardiovascular disease ∵ increases risk of high blood pressure |
What do high-density lipoproteins (HDLs) do? | Remove cholesterol from tissues and transport it to liver for excretion Help protect arteries against heart disease |
What do low-density lipoproteins (HDLs) do? | Transport cholesterol from liver to tissues (artery walls) = atheroma |
Name 2 factors that increase the risk of cardiovascular disease but can't be controlled | Having a genetic predisposition to coronary heart disease High blood pressure as a result of another condition e.g. some forms of diabetes |