the heart

• Pathway of blood through the heart

  1. Deoxygenated blood flows through vena cava into right atrium

  2. Atrium contracts, blood forced into right ventricle

  3. Ventricle contracts, blood pushed through semilunar valve into pulmonary artery

  4. Blood travels to lungs, moves through capillaries past alveoli for gas exchange

  5. Low pressure blood flow prevents damage to lung capillaries

  6. Oxygenated blood returns via pulmonary vein to left atrium

  7. Atrium contracts, blood forced into left ventricle

  8. Ventricle contracts, blood forced through semilunar valve and out through aorta

  9. Thicker muscle walls of left ventricle produce high pressure for blood to travel around body
• • Blood is pumped towards the heart in veins and away from the heart in arteries
• Restriction enzymes are used to cut the required gene out of the DNA; cutting DNA with restriction enzymes results in pieces of DNA with ‘sticky ends’
• hepatic is related to the liver
• pulmonary is related to the lung
• portal is from gut to liver
• renal is related to the kidney
• Veins carry deoxygenated blood back towards the heart
• • A large lumen reduces resistance to blood flow under low pressure
  • Valves prevent the backflow of blood as it is under low pressure
• Nicotine

  • Nicotine narrows blood vessels leading to an increased blood pressure
  • It also increases heart rate
  • Both of these effects can cause blood clots to form in the arteries leading to heart attack or stroke
• • Emphysema develops as a result of frequent infection, phagocytes that enter the lungs release elastase, an enzyme that breaks down the elastic fibres in the alveoli
  • This means the alveoli become less elastic and cannot stretch so many burst
  • The breakdown of alveoli reduces the surface area for gas exchange
  • As it progresses, patients become breathless and wheezy - they may need a constant supply of oxygen to stay alive