Blood and circulation

• The human body has around 5-6 litres of blood
• Components of blood


  • Plasma
  • Red blood cells
  • White blood cells
  • Platelets
• Components of plasma


  • Water: solvent are carrier medium
  • Dissolved substances: proteins, glucose, salts, wastes (urea), hormones (Insulin)
• Red blood cells


  • Transports oxygen
• White blood cells


  • Kills bacteria and diseases
• Platelets


  • Creates blood clots
• Red blood cell


  • Biconcave shape
  • Contains haemoglobin
  • No nucleus
  • Allows more oxygen transport due to increased surface area
• At high altitudes


  Body produces more red blood cells to increase oxygen uptake
• Types of white blood cells

  • Phagocyte
  • Lymphocyte
• Phagocytes


  • Have multiple nucleuses (multi-lobed)
  • Function is to engulf and destroy bacteria and other microbes
• Lymphocytes


  • Have one very large nucleus
  • Function is to produce antibodies which kill invading microbes and make their toxins harmless
• Platelets clotting


  1. Platelets stick to each other

  2. Fibrinogen turns into fibrin

  3. Forms a mesh

  4. Stops the bleeding
• Deamination: excess amino acids turn into urea and glycogen in the liver
• Homeostasis


  Maintains a constant internal environment
• Functions of clotting


  • Stops too much blood from being lost
  • Prevents the entry of harmful bacteria
• All cells have antigens on their surface
• Antibody production


  1. Lymphocytes recognise foreign antigens

  2. Lymphocytes produce antibodies against the foreign antigen

  3. Antibodies stick to the antigens and kill the germs by making them burst, clumping them together so the phagocytes can engulf them, or neutralising their poison
• Antibodies


  Very specific (like the lock and key of enzymes)
• Blood groups


  • A
  • B
  • AB
  • O
• Blood group A


  Has A antigens
• Blood group B


  Has B antigens
• Blood group AB


  Has A and B antigens
• Blood group O


  Has no antigens
• Every blood group can receive from blood group O
• Blood positive/negative


  Determined by presence/absence of Rhesus factor on blood cells
• Someone with blood positive can't receive blood from someone with blood negative
• Components of the circulatory system

  • The heart
  • The pulmonary circulation
  • The systemic circulation
• Pulmonary circulation


  Carries blood from the heart to the lungs and from the lungs to the heart
• Systemic circulation


  Carries blood from the heart to the body and from the body to the heart
• Right side of the heart

  Receives deoxygenated blood
• Left side of the heart

  Receives oxygenated blood
• Blood vessels


  • Pulmonary artery: heart – lungs = deoxygenated blood
  • Pulmonary vein: lungs – heart = oxygenated blood
  • Aorta: left atrium – the body = oxygenated blood
  • Vena cava: the body – right atrium = deoxygenated blood
  • Coronary artery: inside the heart – the cardiac muscle = oxygenated blood
• The pulmonary artery and the pulmonary vein are the only two blood vessels which don't follow the arteries = away, veins = towards rule
• Types of valves


  • Tricuspid valve
  • Bicuspid valve
  • Semi-lunar valves
• Tricuspid valve


  On the right side of the heart, prevents blood from flowing back into the atria
• Bicuspid valve


  On the left side of the heart, prevents blood from flowing back into the atria
• Semi-lunar valves


  Prevent blood from flowing back into the ventricles
• The septum separates the left and right side of the heart
• Blood flow through the heart

  • Vein - Atrium - Ventricle - Artery
• Arteries


  • Narrow lumen
  • Thick elastic, muscular walls