1.4

• Structure of a heart

  A - superior vena cava

  B - aorta

  C - pulmonary artery

  D - pulmonary veins

  E - right atrium

  F - left atrium

  G - tricuspid valve

  H - bicuspid valve

  I - right ventricle

  J - left ventricle

  K - pulmonary valve

  L - aortic valve

  M - inferior vena cava

  N - interventricular septum

  O - septum

  
• Superior vena cava

  • from body
  • deoxygenated blood enters the right atrium via vena cava
• Aorta

  • to body
  • oxygenated blood is pumped from the heart through the aorta
• Pulmonary artery

  • to lung
  • deoxygenated blood is pumped through the pulmonary artery
• Pulmonary veins

  • from lungs
  • oxygenated blood enters left atrium via pulmonary vein
• Tricuspid valve


  prevents backflow into right atrium
• Bicuspid valve


  prevents backflow into left atrium
• Pulmonary valve


  prevents backflow into right ventricle
• Aortic valve


  prevents backflow into left ventricle
• Artery

  • thick muscular wall - withstands high blood pressure
  • pulse - pushes blood through the vessel
  • small lumen - maintains pressure
• Vein

  • thinner wall than artery - allows surrounding muscles to squeeze blood
  • valves - ensures blood only moves toward heart (no backflow)
  • large lumen - increases rate of flow of blood
• Capillary

  • walls are one cell thick - short diffusion pathway
  • blood flow is very slow - time for materials to be exchanged
  • extensive networks in each organ - every cells near a capillary so more materials are exchanged
• Cardiovascular disease

  • related to lifestyle and / or genetics
  • linked to atherosclerosis
  • treated by healthy diet and exercise and use of statin drugs or angioplasty surgery
• Atherosclerosis


  build up of plaque in the walls of an artery
• Angioplasty


  widens narrowed arteries with a stent

  1. stent is attached to a small balloon
  2. balloon inflates to increase the stent width
  3. the balloon deflates and is taken out
  4. stent is left inside artery, propping it open
• Blood cells

  • plasma
  • platelets
  • red blood cells
  • white cells
• Plasma


  carries carbon dioxide and glucose
• Platelets


  cause clotting by forming scabs
• Red blood cells


  carry oxygen
• White cells(phagocytes)


  fight infection
• Double circulatory system

  • blood must go through heart twice to make a full trip around the body
  • has to go through the pulmonary circuit which has low oxygen and high carbon dioxide
  • has to go through the systemic circuit which has high oxygen and low carbon dioxide

  
• Capillaries

  • oxygen diffuses into tissue cells
  • glucose diffuses into tissue cells
  • carbon dioxide diffuses into blood
  • lactic acid diffuses into blood
  • water diffuses into blood via osmosis