Organisms Exchange Substances with their Environment: Mass Transport in Animals - Cardiovascular Disease

Question 1

What is cardiovascular disease?

Answer 1

• Cardiovascular disease is a general term used to describe diseases associated with the heart and blood vessels

Question 2

What is coronary heart disease?

Answer 2

• CHD occurs when the coronary arteries have lots of atheroma in them
• Atheroma restrict blood flow to heart muscle
• Can lead to myocardial infarction (heart attack)

Question 3

What is an atheroma?

Answer 3

• A fibrous plaque that can form on the inner layer of artery endothelium

Question 4

How are atheroma formed?

Answer 4

• Artery endothelium are usually smooth and unbroken
• If damage occurs to endothelium (e.g due to high blood pressure) white blood cells and lipids clump together to form fatty streaks
• More WBC, lipids and connective tissue build up and harden
• They form fibrous plaque called an atheroma

Question 5

How do atheroma impact blood flow and pressure?

Answer 5

• Atheroma partially block lumen and cause them to narrow - restricting blood flow
• Causes blood pressure to increase

Question 6

Which conditions do atheroma increase the risk of?

Answer 6

• Thrombosis

- Aneurysm

Question 7

What is an aneurysm?

Answer 7

• An aneurysm is a balloon-like swelling of the artery

Question 8

How do aneurysms form?

Answer 8

• Starts with formation of atheroma
• Atheroma plaques damage and weaken arteries
• This narrows arteries, increasing blood pressure
• When blood travels through a weakened artery at high pressure, it may push the inner layers of the artery through the outer elastic layer to form an aneurysm
• This aneurysm may burst, causing a haemorrhage (bleeding)

Question 9

What is thrombosis?

Answer 9

• Thrombosis is the formation of a blood clot

Question 10

What causes thrombosis?

Answer 10

• Starts with formation of atheroma
• An atheroma plaque can break the endothelium (inner lining of artery)
• This damages the artery and leaves a rough surface
• Platelets and fibrin (a protein) accumulate at site of damage and form a blood clot (a thrombus)

Question 11

How does thrombus affect blood flow?

Answer 11

• Blood clots can completely block arteries - reducing blood flow
• Can become dislodged and block a blood vessel elsewhere in the body

Question 12

Which blood vessels supply blood to the heart?

Answer 12

• Coronary arteries

Question 13

What happens if a blood clot completely blocks a coronary artery?

Answer 13

• An area of the heart muscle will be cut off from its heart supply and will receive no oxygen
• This causes a myocardial infarction aka a heart attack

Question 14

What do heart attacks do to the heart and what are the symptoms?

Answer 14

• A heart attack can cause damage and death of the heart muscle
• Symptoms include pain in the chest and upper body, shortness of breath and sweating
• If large areas of heart muscle are affected complete heart failure can occur, often fatal