Biology - Risk of Cardiovascular Disease 1

Biology - Risk of Cardiovascular Disease 1

1. Risk?

   • 'The probability of occurrence of some unwanted event or outcome'
   • Example calculation of risk: 19,429 UK people died of an injury/poisoning in 2005. Total population at the time was 60,209,408, so we can calculate this as an average risk
     • 19,429 in 60,209,408... OR 1 in 60,209,408÷19,429 --> =1 in 3099 --> =1÷3099 --> =0.00032 OR 0.032%

2. Factors that Increase the Risk of Cardiovascular Disease

   • Lifestyle
     • DIET - high in saturated fat increases blood cholesterol level, which increases atheroma formation. High salt levels increase blood pressure
     • HIGH BLOOD PRESURE - increased risk of damage to artery walls
       • Other causes include excessive alcohol consumption, stress and diet
     • SMOKING - carbon monoxide combines with HAEMOGLOBIN in the blood, reducing the amount of oxygen being transported
       • NICOTINE makes platelets more sticky so blot clots can form easily
       • Amount of ANTIOXIDANTS (help protect cells) in the blood decreases - increased risk of CVD
     • INACTIVITY - lack of exercise leads to high blood pressure
   • Beyond Our Control
     • GENETICS - some people inherit particular alleles which make them more likely to have high blood pressure or high cholesterol levels
     • AGE - increased age increases the risk of CVD
     • GENDER - men are at greater risk

3. High Blood Pressure (Hypertension)

   • Measure of the hydrostatic force of the blood against blood vessel walls
   • A SPHYGMOMANOMETER measures blood pressure - for a healthy average person the reading should be 100-140mmHg for SYSTOLIC pressure and 60-90mmHg for DIASTOLIC pressure
   • What determines your blood pressure?
     • Contact between blood and vessel walls causes FRICTION and effects the flow of blood - PERIPHERAL RESISTANCE
       • ARTERIOLES and CAPILLARIES have greater total SURFACE AREAS --> more friction --> more resistance --> slower blood flow --> lower pressure
     • If the walls of an artery/arteriole contract, the vessel contracts, increasing resistance
       • If they relax, the lumen is dilated, so the resistance falls
     • OEDEMA - fluid building up in tissues and causing swelling
       • At the arterial end of a capillary, blood is under pressure. This forces fluid through the capillary walls into the intercellular spaces, forming TISSUE FLUID
         • The capillary walls prevent blood cells and larger plasma proteins from passing through though
         • High blood pressure means more of the fluid is forced out of the capillaries

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