Topic 3 - risk factors

Question 1

Smoking as a risk factor

Answer 1

Reduces levels of HDLs

Carbon monoxide increases deposition of cholesterol in atheroma formation

Increases heart rate + causes vasoconstriction to increase blood pressure increases risk of damage to lining of arteries increases risk of atherosclerosis

Contents in smoke (e.g. free radicals) which get into blood stream can damage endothelium lining of blood vessels

Question 2

More on smoking

Answer 2

Carbon monoxide combines irreversibly with haemoglobin to produce carboxyhaemoglobin which cannot carry oxygen

so oxygen-carrying capacity of blood reduced

If blood flow is reduced due to atherosclerosis tissues get even less oxygen which can increase risk of cell damage/death

Nicotine also increases stickiness of platelets so increasing risk of blood clots, especially in the coronary arteries  increased risk of CHD

Question 3

Salt

Answer 3

In general terms our diet contains too much salt, especially in all the processed foods we eat. Just look at the food labels!

Only 6g per day recommended (most people normally eat > 10 g per day!)

A high salt diet causes the kidneys to retain too much water

so higher fluid content in the blood increases blood volume

which increases blood pressure

which can increase risk of CVD

Question 4

Exercise

Answer 4

Exercise improves coronary circulation, which decreases the risk of CVD.

Exercise also increases HDL levels which helps to lower bad cholesterol (LDL’S).

Lower levels of exercise make the heart inefficient, as the cardiac output is reduced. The heart rate increases and the artery walls become less elastic.

Question 5

Vitamins as antioxidants

Answer 5

Free radicals – highly reactive chemicals (atom with an unpaired electron) produced by some normal metabolic reactions in the body or in reactions that breakdown toxins (including those found in cigarette smoke).

Act as oxidising agents – can damage DNA, proteins and other molecules

Damage is cumulative over time, so associated with ageing

Oxidised LDLs more readily taken up by white blood cells involved in atherosclerosis, hence CHD

Antioxidants help prevent damage caused by free radicals (provide H atoms to pair up with the unpaired electron)
Good sources of dietary antioxidants include:

Vitamin C
e.g. from citrus fruits, broccoli, tomatoes

Vitamin E
e.g. from wholegrain cereals, bread, peanuts, fish

Beta-carotene (used to make vitamin A)
e.g. carrots, sweet potatoes, spinach, peaches, mangoes

Question 6

Obesity

Answer 6

Obesity defined as having a BMI > 30

BMI = body mass index = body mass in kg / (height in m)2

Increases risk of CHD

Blood pressure increases

Blood LDL cholesterol level increases which increases the risk of atheroma and atherosclerosis
[Blood supply in coronary arteries blocked; reduced blood supply reduces supply of oxygen  can lead to damage or death to heart muscle cells

 heart unable to beat properly = heart attack]

Increases risk of type II diabetes which also increases risk of CHD as elevated glucose levels cause high blood pressure.

Question 7

High density lipoproteins = HDLs (unsaturated fats)

Answer 7

HDLs are ‘good cholesterol’

transport cholesterol absorbed from food to liver to be broken down (some excreted in bile)

so get rid of cholesterol

so lowers blood cholesterol

so prevent cholesterol deposition in artery walls

so prevent atherosclerosis

Question 8

Low density lipoproteins = LDLs(saturated fats)

Answer 8

LDLs are ‘bad’ cholesterol

circulate in bloodstream

not taken up by body cells so not removed

so blood cholesterol levels high

this get deposited in artery walls  atheroma

[leading to atherosclerosis which narrows the arteries reducing the blood supply which increases the risks of CHD]

Question 9

Alcohol

Answer 9

Alcohol decreases the blood flow to the muscles (including the heart), this can lead to coronary heart disease.

It increases blood pressure by constricting the arteries.

It also has an effect on the rhythm on the heart which can lead to arrhythmia.

It is also calorie rich and can lead to obesity.

Question 10

Age and gender

Answer 10

Women have naturally higher HDL levels reducing their risk of atheroma. This is due to higher oestrogen levels.

Oestrogen also increases the blood flow to the muscles (including the heart).

Arteries become less elastic with age which can increase blood pressure and the risk of blood vessel damage.

Question 11

Genetics

Answer 11

Some alleles increase the risk of CVD, these are inherited from family members.

These alleles may cause a variety of problems e.g. valve weakness, high blood pressure, high LDL and cholesterol levels.

Some can be beneficial e.g. high HDL levels which helps lower cholesterol.

Question 12

Stress

Answer 12

This causes the release of adrenaline which increases the heart rate and constricts the arteries.

People with stressful jobs (the 3 most stressful statistically are: miners, emergency services and teachers) are most at risk.