Blood

• Red blood cells

  • packed with haemoglobin
  • carries oxygen around the body
  • no nucleus
  • flattened discs with a large SA for diffusion
• White blood cells

  • protect against diseases
  • much larger than red blood cells
  • fewer numbers than red blood cells
• Platelets

  • cell fragments needed for blood clotting
  • clots to prevent blood loss
  • clots stop the entry of pathogens and infections
• Plasma

  • a yellowy liquid that transports all you blood cells around the body
  • CO2 is carried to the lungs
  • Urea is transported from your liver to your kidneys to make urine
  • the products of digestion are carried from the small intestine to the cells where they are needed
• Artery

  • carries blood away from the heart
  • lumen is small
  • blood in under high pressure
  • artery is made of thick muscle and elastic fibres
• Capillary

  • very small vessels
  • one cell thick
  • oxygenated enters and deoxygenated leaves
  • allows substances to leave the blood to go to the cells and leave the cells to enter the blood
• Vein

  • carry blood back to the heart
  • the blood is under less pressure
  • lumen is large
  • thinner walls than arteries
  • they have valves to help get blood back to the heart.
• left atrium-left ventricle-aorta-body-vena cava- right atrium- right ventricle-pulmonary artery-lungs-pulmonary vein- back to the left atrium