1_Blood & Circulation

1_Blood & Circulation

1. Red Blood Cells

   • Contain no nucleus ( have a dip in the centre)>more oxygen carried
   • Large surface area compared to volume > oxygen close to surface

2. Platelets

   • Platelets clot the blood after a wound > prevents infection and blood loss
   • People with haemophilia have a faulty gene for the clotting process

3. White Blood Cells

   • Larger than red blood cells, flexible shape to help engulf disease organism
   • Protects against infection by digesting harmful microbes, bacteria digested inside WBC
   • Able to squeeze out of capillaries to defend different tissues

4. Plasma

   • Contains mostly water, dissolved food, urea, hormones and carbon dioxide
   • Pale yellow fluid carries blood cells, useful substances and waste around the body through blood vessels

5. Pulmonary Artery > Carries blood from the heart to the lungs

6. Aorta (Artery) > Carries blood from heart to body

7. Pulmonary Vein > Carries blood from lung to heart

8. Vena Cava (Vein) > Carries blood from body to heart

9. heart

   • how is works
     • blood flows into the atrias from the vena cava and pulmonary vein
       • atria contracts pushing blood into the ventricles
         • ventricles contract forcing blood to the lungs through the pulmonary artery and to the body through the aorta
           • blood flows to the heart from the bady through the vena cava and from the lungs through the pulmonary vein
             • this refills the atrias and restarts the process

10. blood vessels

    • Arteries = Away
      • Arteries have thick walls because the blood pressure is very high. They also have thick elastic walls
    • Capillaries = Small cells
      • walls are one cell thick to allow substances to be transferred
    • veins=away
      • veins have valves to prevent backflow