Risk factors for CVD

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Risk factors for CVD

Obesity as it raises blood pressure and blood lipid levels

Saturated fat in diet as it increases blood pressure

High cholesterol- Cholesterol is not soluable in water. In order to be transported in the bloodstream, insoluble choleserol is combined with proteins to form soluble lipoproteins. 

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Lipoproteins (LDL's)

Main cholesterol carrier 

Triglycerides from saturated fats which combine with cholesterol and protein membranes and are then taken up by cells. 

Excess LDL's overload membrane receptors resulting in higher cholesterol levels. 

Saturated fats reduce activity of LDL receptors so they are not removed from blood increasing blood cholesterol levels. 

Depoisited in artery walls forming antheromas 

Monounsaturated fats help removel of LDL's from blood 

Polyunsaturated fats increase the activity of LDL's receptor sites so LDL's are removed from blood

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Lipoproteins (HDL's)

Higher density as they have a higher percentage of proteins. 

Triglycerides form unsaturated fats which combine with cholesterol and proteins

HDL's transport cholesterol from body tissues to the liver where it is broken down. 

Lowers cholesterol levels and removes fatty plagues of a atheroschlerosis

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Inactivity

Exercise raises HDL cholesterol levels without affecting LDL cholesterol levels. It reduces the risk of type 2 diabetes and controls it. 

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Salt

A high salt diet causes the kidney's to retain water. Higher fluid levels in the blood result in elevated blood pressure with the associated CVD risks.

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Smoking

Haemoglobin carries CO instead of O2 reducing O2 levels in the blood. Artheroclosis reduces blood flow by narrowing the arteries further reducing O2 levels. This results in increased heart rate. Nicotine stimulates adreneline which causes increased heart rate and arteries to constrict raising blood pressure. Chemicals damage the lining of the artereis triggering artheroclosis. Reduction in HDL cholesterol levels. 

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Stress

Stress causes the release of adreneline which causes arteries and arterioles to constrict resulting in high blood pressure. Stress can also lead to overeting, poor diet and higher alcohol consumption.

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Antioxidants

Radicals (unstable radicals result when an atom has an unpaired electron) are highly reactive and can damage many cell components including enzymes and genetic material. Implicated in development of some cancers, heart disease, premature aging. Some vitamins protect against radical damage. They provide hydrogen atoms which pair up with its unpaired electron. High levels of antioxidants protect against heart disease. 

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Alcohol

Heavy drinking raises blood pressure, contributes to obesity and can cause irregular heartbeat. Heavy drinking can result in direct tissue damage, including damage to liver, brain and heart. Liver processes Carbohydrates, fats and proteins and detoxification including alcohol. Heavy drinking damages liver cells. This impairs removal of glucose and lipids from blood. Alcohol is converted to ethanol, three carbon carbohydrates. Most is used in respirationbut some ends up in low density lipoproteins increasing the risk of plague deposition. Moderate alcohol comsumption is collelated with higher HDL cholesterol levels.  

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Heriditary

Some single gene disorders for example hypercholesterolaemia, mutations in LDLR gene, cause LDL receptors not to form. This results in high LDL levels. Even with this gene mutation CHD will be dependant on other factors. The alpoliprotein gene cluster has been identified as associated with CHD. Alpoliproteins are the protein component of lipoproteins. Formed in liver stabilising structure of lipoproteins and recognising receptors involved in Lipoprotein uptake on the plasma membrane of most cells. Families do not just pass on genes, you may also aquire parents lifestyle.

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Apolipoproteins

Apolipoprotein A (APOA) is a major protein in HDL, which helps in the removal of cholesterol from the blood to cells. Mutations in the apoB gene are associated with low HDL levels and reduced removal of cholesterol from the blood, leading to increased risk of heart disease. 

Apolpoprotein B (APOB)- the main protein in LDL, the molecule with transfers cholesterol from the blood to cells. Mutations of the apoB gene result in higher levels of LDL in the blood and a higher susceptibility to CVD. 

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Apolipoproteins continued

Apolipoprotein E (APOE)- a major component of HDL's and very low density lipoproteins (VLDL's), which are also involved in removal of excess cholesterol from the blood to the liver. The apoE gene has three common alleles, producing three forms of the protein E2, E3 and E4. APOE4 slows removal of cholesterol from the blood and therefore having the APOE4 allele may increase the risk of coronary heart disease. APOE2 lowers cholesterol in the blood reducing the risk of developing CVD.

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