5.2 Heart Disease

Question 0

What is Atheroma?

Answer 0

Atheroma is a fatty deposit that forms within the wall of an artery.

Question 1

Which disease are about half of heart disease deaths due to?

Answer 1

Coronary heart disease (CHD)

Question 2

How does Atheroma begin?

Answer 2

Atheroma begins as fatty steaks that are accumulations of white blood cells that have taken up low-density lipoproteins (LDLs).

Question 3

In Atheroma, what do the fatty streaks develop into?

Answer 3

The streaks enlarge to form an irregular patch, or atheromatous plaque.

Atheromatous plaque most commonly occurs in large arteries and are made up of deposits of cholesterol, fibres and dead muscle cells.

Question 4

How does Atheroma restrict blood flow and which two conditions do they increase the risk of?

Answer 4

The plaque bulges into the lumen of the artery.

They increase the risk of thrombosis and aneurysm.

Question 5

Remember - plaques are formed…

Answer 5

WITHIN the artery wall. They are not deposits on the inner surface of the artery wall.

Question 6

What is a thrombus?

Answer 6

If an Atheroma breaks through the lining of the blood vessel it forms a rough surface that interrupts the otherwise smooth flow of blood. This may result in the formation of a blood clot or thrombus - in the condition thrombosis.

Question 7

How do thrombuses reduce blood supply?

Answer 7

The thrombus blocks the blood vessel, reducing or preventing supply of blood to tissues beyond it. This tissue will die. The thrombus is sometimes carried from its place of origin and loges in and blocks another artery.

Question 8

What is an aneurysm?

Answer 8

Atheromas that lead to the formation of a thrombus weaken artery walls. These weakened points swell to form a ballon-like, blood-filled structure called an aneurysm.

Question 9

Why are aneurysms dangerous?

Answer 9

Aneurysms frequently burst, leading to haemorrhage and therefore loss of blood to the region of the body served by that artery.

Question 10

What is a brain aneurysm also known as?

Answer 10

A cerebrovascular accident (CVA) or stroke

Question 11

What is the official name for a heart attack?

Answer 11

A myocardial infarction.

Question 12

How does a myocardial infarction arise?

Answer 12

It results from the blockage of the coronary artery.

Question 13

Why does the heart stop beating in myocardial infarction?

Answer 13

The blood supply to the cardiac muscle is completely cut off.

Question 14

When are symptoms of myocardial infarction milder?

Answer 14

If the blockage is further along the coronary artery because a smaller area of muscle will suffer oxygen deprivation.

Question 15

In Britain, how many people a year have a heart attack?

Answer 15

About half a million people but fewer than one third of them die as a result.

Question 16

What are the risk factors associated with coronary heart disease?

Answer 16

Smoking
High blood pressure
Blood cholesterol
Diet

Question 17

Name the two main constituents of tobacco smoke that increase the likelihood of heart disease.

Answer 17

Carbon monoxide

Nicotine

Question 18

Describe the effects of carbon monoxide on oxygen supply.

Answer 18

Carbon monoxide combines irreversibly with haemoglobin in red blood cells to form carboxyhaemoglobin. It reduces the oxygen carrying ability of blood.

The tissues must work harder. This increases blood pressure and the risk of heart disease and strokes. During exercise the blood cannot supply the heart muscle with oxygen sufficiently. This leads to chest pain (angina) or myocardial infarction.

Question 19

What effect does nicotine from tobacco smoke have on oxygen supply?

Answer 19

Nicotine stimulates the production of the hormone adrenaline, which increases heart rate and raises blood pressure. This leads to increased risk of smokers suffering coronary heart disease or a stroke.

Nicotine also makes the platelets in the blood more sticky which leads to higher risk of thrombosis.

Question 20

How does high blood pressure increase the risk of heart disease?

Answer 20

• as there is already a higher pressure in the arteries, the heart must work harder to pump blood into them and is therefore more prone to failure
• higher blood pressure within the arteries means that they are more likely to develop an aneurysm and burst causing haemorrhage.
• to resist the higher pressure within them, the walls of the arteries tend to become thickened and may harden restricting blood flow.

Question 21

Name the two types of cholesterol

Answer 21

High-density lipoproteins (HDLs)

Low-density lipoproteins (LDLs)

Question 22

What is cholesterol an essential component of and how is it transported in the body?

Answer 22

Membranes. It is carried in the plasma as tiny spheres of lipoproteins (lipid and protein)

Question 23

What is the role of HDLs?

Answer 23

They remove cholesterol from tissues and transport it to the liver for excretion. They help to protect arteries against heart disease.

Question 24

What is the role of LDLs?

Answer 24

They transport cholesterol from the liver to the tissues, including the artery walls, which they infiltrate, leading to the development of Atheroma and hence heart disease.

Question 25

How does diet increase risk of heart disease?

Answer 25

High levels of salt raise blood pressure

High levels of saturated fat increase low-density lipoprotein levels and hence blood cholesterol concentration

Question 26

Which foods reduce the risk of heart disease?

Answer 26

Antioxidants e.g vitamin C and non-starch polysaccharide

Question 27

If electrical waves produced in the heart are picked up by a cathode ray oscilloscope what can be produced?

Answer 27

An electrocardiogram

Question 28

In a healthy heart’s ECG, what can be seen?

Answer 28

There is a pattern of large peaks and small toughs that repeat identically at regular intervals.

Question 29

In a heart attack ECG what can be seen?

Answer 29

Shows less pronounced peaks and larger troughs that are repeated in a similar but not identical way.

Question 30

In a ECG of a condition called fibrillation, what can be seen?

Answer 30

The heart muscle contracts in a disorganised way - very irregular