The circulatory system

• Mode of the bleed, heart and blood vessels, it's job is


  1. Transport blood around the body

  2. Carry oxygen from the lungs

  3. Carry glucose from digestion to the cells

  4. Carry waste substances to be renewed free the body
• Blood components


  • Red Blood Cells
  • White Blood Cells
  • Platelets
  • Plasma
• Red Blood Cells


  Carry oxygen, biconcave shape gives increased surface area to volume ratio for diffusion of oxygen, contain haemoglobin which binds to oxygen
• White Blood Cells


  Make up the immune system, attack invading microorganisms (pathogens)
• Platelets


  Fragments of cells, cause clotting at the site of wounds
• Plasma


  Straw-coloured fluid in which the platelets, red and white blood cells are suspended, carries dissolved CO2 and glucose
• Blood vessels


  • Arteries
  • Veins
  • Capillaries
• Arteries


  • Thick muscular, elastic walls and lumen
  • Relatively high pressure
• Veins


  • Relatively thin walls
  • Large lumen
  • Have valves to prevent backflow
• Capillaries


  • Very narrow lumen
  • Only 1 cell thick
• Heart


  Muscular organ, the circulatory system's pump, double circulatory system
• Blood flow through the heart

  1. Picks up oxygen from the lungs

  2. Enters the left atrium

  3. Pumped into the left ventricle

  4. Pumped out to deliver oxygen to body parts

  5. Becomes deoxygenated

  6. Returns to the right atrium

  7. Pumped through the pulmonary artery to pick up more oxygen from the lungs
• Arteries


  • Carry blood away from the heart
  • Strong and can stretch to deal with high pressure
  • Walls made of muscle and elastic tissue
• Veins

  • Carry blood towards the heart
  • Valves prevent backflow of blood
• Capillaries


  • Tiny vessels found in lungs and body parts
  • Only 1 cell thick, allow oxygen and CO2 to diffuse
• Coronary heart disease


  Layers of fatty material build up inside the coronary arteries, narrowing them and reducing blood flow to the heart muscle
• Treatments for coronary heart disease


  • Pacemakers
  • Stents
  • Valve replacement
  • Heart transplants
• Pacemakers provide electrical pulses to control the heart rate
• Stents open the coronary arteries to keep blood flow to the heart muscle
• Valve replacement can be with biological or mechanical valves
• Heart transplants are used when the patient's own heart fails
• High cholesterol can lead to coronary heart disease