Cardiovascular Disease

• Atheroma formation


  The process in which the artery lining becomes hard due to the build-up of fatty material in the artery wall
• Atherosclerosis


  • It can lead to the artery becoming completely blocked, cutting off blood circulation and leading to events like a heart attack or stroke
• Stages of atheroma formation


  1. The inner lining of the artery wall (the endothelium) becomes damaged due to high blood pressure (hypertension)

  2. This triggers an inflammatory response - white blood cells (such as macrophages) move towards the site of damage and accumulate with lipids (fats) which are circulating in the blood

  3. The accumulation of these substances underneath the artery wall leads to the formation of fatty streaks in the endothelium

  4. The fatty streaks develop into an atheroma, causing the lumen of the artery to become narrower and restricting blood flow

  5. The hardening of arteries, caused by the development of atheromas, is referred to as atherosclerosis
• Atheroma formation:

  
• Cardiovascular disease


  The formation of an atheroma in an artery causes partial blockage of an artery. If the atheroma ruptures, it can trigger a blood clot to form which may completely prevent blood flow.
• Stages of atheroma rupture and blood clot formation


  1. Atheroma ruptures and bursts through the endothelium of the artery, damaging the artery wall

  2. This triggers blood clotting (thrombosis) at the site of damage

  3. The blood clot can cause a complete blockage within the artery

  4. This prevents blood flow in the artery which means that oxygen isn't delivered to the tissues downstream of the artery

  5. The cells within the tissue cannot carry out aerobic respiration and will start to die
• If the blockage happens within a coronary artery


  It will lead to a heart attack
• If the blockage occurs in a blood vessel leading to the brain

  It will cause a stroke
• If the blockage happens in an artery in the legs

  It can cause deep vein thrombosis
• Blockage of artery:

  
• Blood clotting


  The process of platelets clumping together at the site of a wound to prevent excessive blood loss and entry of microorganisms
• When blood clotting happens inside arteries


  It can completely restrict blood flow within the vessel
• Blood clotting (thrombosis)


  1. Enzyme thromboplastin is released from damaged blood vessels

  2. Thromboplastin catalyses the formation of prothrombin into thrombin

  3. Thrombin catalyses the formation of fibrinogen into fibrin

  4. Fibrin forms insoluble fibres that tangle together platelets and red blood cells to form a blood clot
• Thromboplastin

  An enzyme released from damaged blood vessels that requires calcium ions to function
• Thrombin


  An enzyme formed from the catalysis of prothrombin by thromboplastin
• Risk factors for CVD


  • Lifestyle factors
  • Non-lifestyle factors
• Lifestyle factors


  Things which result from our behaviour and are under our control
• Non-lifestyle factors


  Things that we were born with and cannot control
• Genes you have


  You may be more susceptible to high blood pressure, which is also affected by your diet
• Smoking


  • Nicotine in cigarette smoke makes platelets stickier, increasing the chance of a blood clot forming
  • Carbon monoxide in cigarette smoke binds to haemoglobin in red blood cells, reducing the amount of oxygen being transported in the blood
  • Smoking reduces levels of antioxidants in the blood, which can increase the likelihood of endothelial damage and atheroma formation
• High blood pressure


  Puts more strain on the artery walls and means they are more likely to suffer damage, leading to atherosclerosis and cardiovascular disease
• Factors that can increase blood pressure


  • Diet high in salt
  • High alcohol consumption
  • Inactivity
  • Stress
• Diet high in saturated fats and low in unsaturated fats


  Can increase the risk of CVD by increasing blood cholesterol levels and the likelihood of atheroma formation
• Diet high in salt


  Can increase the risk of CVD by increasing blood pressure
• Lack of exercise


  Can increase the chances of CVD by increasing blood pressure
• Age


  The risk of CVD increases with age as fatty deposits accumulate in arteries over time
• Genetics


  • Some people possess alleles which increase cholesterol production or make them more susceptible to high blood pressure
  • Some people can inherit beneficial alleles which will reduce their risk of CVD by dampening down cholesterol production or giving them slightly lower blood pressure
• Gender


  Men are at a much greater risk of developing CVD than women due to lower oestrogen levels, which increases 'good' cholesterol (HDLs) and reduces the risk of atheroma formation
• Antihypertensives


  Beta-blockers and vasodilators are two types of drug which act as antihypertensives since they work by lowering blood pressure
• Lower blood pressure


  Lower risk of endothelial dysfunction (damage to the artery wall)
• Side-effects of antihypertensives


  • Heart palpitations
  • Fainting
  • Headaches
  • Drowsiness
• Statins


  Drugs which work by reducing cholesterol levels by lowering the LDL concentration in the blood
• Side-effects of statins


  • Muscle pain
  • Nausea
  • Headaches
  • Increased risk of diabetes
  • Problems with the digestive system
• Anticoagulants


  Substances which reduce blood clotting
• Risks of anticoagulants


  • Excessive bleeding if the person injures themselves
  • Allergic reactions
  • Tissue swelling
• Platelet inhibitors


  Substances which reduce blood clotting by preventing platelets from sticking together
• Side-effects of platelet inhibitors


  • Rashes
  • Nausea
  • Diarrhoea
  • Excessive bleeding if an injury occurs