Health and disease

• • The heart is made of cardiac muscle cells which like all cells in the body need a supply of blood to deliver oxygen, glucose and other nutrients and remove waste products such as carbon dioxide
  • The blood is supplied to the heart by the coronary arteries which branch off directly from the aorta
  • The heart needs to constantly respire, so it is vital that it receives oxygen
• • In coronary heart disease (CHD), layers of fatty material build up inside the coronary arteries
  • These fatty deposits are mainly formed from cholesterol; of which there are two sources in the body:
  • Dietary cholesterol (from animal products eaten)
  • Cholesterol synthesised by the liver
• • If a coronary artery becomes partially or completely blocked by these fatty deposits, it loses its elasticity and cannot stretch to accommodate the blood which is being forced through every time the heart contracts
• • This reduces the flow of blood through the arteries, resulting in a lack of oxygen for the heart muscle
  • Partial blockage of the coronary arteries creates a restricted blood flow to the cardiac muscle cells and results in severe chest pains called angina
  • Complete blockage means cells in that area of the heart will not be able to respire aerobically, leading to a heart attack
• Treating CHD: Stents

  • Stents can be used to keep the coronary arteries open
  • A narrow tube is threaded up through the groin up to the blocked vessel
  • A tiny balloon is then inflated
  • The balloon pushes the metal or plastic stent against the wall of the artery, increasing the width of the lumen
  • The balloon and tube are then removed
• • Stents are very effective at reducing the risk of a heart attack as they widen the lumen to increase blood flow to the coronary arteries, and the procedure is relatively simple
  • Stents also last a long time, which is a positive, however, there is a risk of blood clots (thrombosis) occurring around
• Statins are not suitable for everyone - they should not be prescribed for people with liver disease, or pregnant or breast feeding women. Some patients taking statins often experience side-effects such as headaches and memory loss. There have been reports of statins being linked with type 2 diabetes. and liver damage.
• • The heart valves play a vital role in ensuring blood is pumped from the ventricles to the arteries
  • In some people, heart valves may become faulty as a result of illness, old age or a heart attack
  • Valves can stiffen which can prevent them opening fully to let blood flow through
  • This reduces the volume of blood pumped by the heart
• • Sometimes a faulty heart valve might develop a leak
  • This allows blood to flow from the ventricles to the atria or the arteries to the ventricles
  • Both issues reduce the effectiveness of the heart in pumping oxygenated blood around the body
  • Faulty heart valves can be replaced via surgery using biological valves from cows or pigs, or mechanical valves
• • In the case of heart failure, a heart or heart and lungs for individuals with diseased lungs can be transplanted from a donor who has recently died
  • However, waiting lists for organs are long and not immediately available, so a short-term solution (or long-term solution if necessary) involves replacing the heart with an artificial one made from plastic and metal
  • They may be used to keep patients alive whilst waiting for a heart transplant, or to allow the heart to rest as an aid to recovery
• Advantages of using artificial hearts

  • Less of a wait for one to become available (as they are manufactured)
  • Less chance of the patient's immune system rejecting the artificial heart
• Disadvantages of using artificial hearts


  • They don't always work as well as real hearts at pumping blood around the body
• Smoking causes diseases such as; lung disease, lung cancer and cardiovascular disease

  • It caused by chemicals, such as tar and nicotine, which damage the alveoli and endothelial lining of the artery
• Obesity, caused by a poor diet, causes Type 2 diabetes

  • The excess sugar in the diet causes the pancreas to not respond to insulin
• The consumption of alcohol causes diseases such as liver disease and impaired brain function

  • The breakdown of alcohol cells by the liver produces substances that are toxic to the liver at a high concentration
• The consumption of alcohol causes diseases such as liver disease and impaired brain function

  • The breakdown of alcohol cells by the liver produces substances that are toxic to the liver at a high concentration
  • The alcohol also causes the neurons to be damaged, which reduces brain function
• Exposure to carcinogens can cause cancer.

  • Exposure to radiating ions Can damage DNA cells, leading to uncontrolled cell division; causing cancer
• Smoking and consuming alcohol during pregnancy can cause birth defects, such as poor growth of the foetus

  • Carbon Monoxide in cigarettes, reduces the volume of oxygen transported around the mothers body, which in turn reduces the oxygen transported to the baby
  • Substances in alcohol can impair the brain growth of the foetus
• Sampling


  Allows researchers to infer (deduce/conclude) information about a population without having to investigate every individual which would be time-consuming and essentially impossible to do accurately
• Cancer


  Caused as a result of changes in the DNA of cells that lead to uncontrolled growth and division - this can result in the formation of a tumour (a mass of cells)
• Benign tumours


  Growths of abnormal cells which are contained in one area, usually within a membrane, and do not invade other parts of the body
• Malignant tumours


  Cancer cells that invade neighbouring tissues and spread to different parts of the body via the blood and lymphatic system where they form secondary tumours, disrupting the functioning of the organs they originate in and spread to
• Individuals with faulty mismatch repair (MMR) genes are more likely to develop cancers of the bowel and reproductive systems