Risk factors 2

BMI

Body mass index is a conventionally used method of classifying body weight relative to a person's height. To calculate BMI, body mass in kg, divided by height (in metres) squared.

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Waist to hip ratio

Calculated by dividing waist circumference by hip circumference.

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Consequences of obesity

Increase risk of coronary heart disease and stroke. More excess fat carried, greater risk to heart. Increase risk of diabetes II, which increase coronary heart disease and stroke. Raise blood pressure and blood lipid levels, cardiovascular disease

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Why is cholesterol such a problem?

The higher your blood cholesterol level, the greater your risk of coronary heart disease. Cholesterol is not soluble in water. In order to transport it in the bloodstream, insoluble cholesterol is combined with proteins to form soluble lipoproteins.

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Low-density lipoproteins

Main cholesterol carrier. Triglycerides from saturated fats combine with cholesterol and proteins to form LDLs. Circulate in blood, bind to receptor sites on cell membranes, taken up by cells. Excess LDLs in diet overload membrane receptors.

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Results in high cholesterol levels. Saturated fats may also reduce the activity of LDL receptors so LDLs are not removed from blood. Cholesterol may be deposited in artery walls> atheromas

High-density lipoproteins

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HDLs have a higher percentage of protein compared with LDLs hence their higher density. High-density lipoproteins are made when triglycerides from unsaturated fats combine with cholesterol and protein.

HDLs transport cholesterol from the body tissue to the liver where it is broken down. This lowers blood cholesterol levels and helps removes the fatty plaques of atherosclerosis

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Carbohydrates effects on lipoproteins

Monosaturated fats are thought to help in the removal of LDLs from the blood. Polysaturated fats are thought to increase the activity of the LDL receptor sites so the LDLs are actively removed from the blood.

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Consequences of lipoproteins

LDLs associated with formation of atherosclerosis plaques whereas HDLs reduce blood cholesterol deposition. Desirable to maintain higher level of HDL, lower of LDL. Avoid saturated fat> reduce total blood cholesterol.

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Conflicting evidence

Many studies provide evidence for a positive correlation between fat consumption and CHD mortality rates. However, conflicting evidence has been produced. Different cultures vary. Other factors can be contributing to cardiovascular disease mortality

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Smoking; affect the circulatory system

Haemoglobin carries carbon monoxide from smoke instead of oxygen. Reduces supply of oxygen to cells. Any narrowing of the arteries due to atherosclerosis will reduce blood flow through the arteries in the heart and brain.

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This further reduces the oxygen supply to the cells of the heart and brain. This will result in an increased heart rate as body react to provide enough oxygen for cells.

Nicotine in smoke stimulates production of adrenaline. Increases heart rate, cause arteries to constrict, raise blood pressure. Numerous chemical in smoke damage lining of the arteries, triggering atherosclerosis. Linked to reduction in HDL level

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Inactivity

Moderate exercise can prevent high blood pressure. Seems to raise HDL without affecting LDL levels. Reduces chance of type II cholesterol. More likely to survive a heart attack or stroke.

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Inheritance

If one or other parent suffered from CVD, more likely to develop it. LDLR mutations cause LDL receptors not to form, different shape, less efficient. High blood LDL with early onset of CHD. Will still depend on diet and lifestyle.

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Apolipoproteins

Protein components of lipoproteins. They are most formed in the liver and intestines and have important roles in stabilising structure of lipoproteins and recognising receptors involved in lipoprotein uptake on the plasma membrane of most cells

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Apolipoprotein A

The major protein in HDL, helps removal of cholesterol to the liver for excretion. Mutation of the apopA gene associated with low HDL level and reduced removal of cholesterol from blood, risk of CHD

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Apolipoprotein B

Main protein in LDL, molecule which transfers cholesterol from blood to cells. Mutations result in higher levels of LDL in blood and a higher susceptibility to CVD

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Apolipoprotein E

Major component of HDLs, involved in removal of excess cholesterol from the blood to the liver. The allele apoE4 slow removal of cholesterol, having allele may increase risk of coronary heart disease.

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Multifactorial

The combination of risk factors experience by the individual determines their risk of developing the disease

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Antioxidants

Some vitamins can protect against radical damage on enzymes and genetic material. They provide hydrogen atoms that stabilise the radical. High levels of antioxidants seemed to protect against heart disease.

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Salt

A high-salt diet causes the kidneys to retain water. Higher fluid levels in the blood result in elevated blood pressure with the associated cardiovascular disease risk

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Stress

Stressful situations; the release of adrenaline causes arteries to constrict, resulting in raised blood pressure, stress can also lead to overeating, a poor diet and higher alcohol consumption, which are all potential contributors to CVD.

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Risk factors 2

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