Biology

• What the blood contains in mammals

  • Red blood cells
  • White blood cells
• Blood

  Transports nutrients, oxygen and carbon dioxide around the body
• Phagocyte (White blood cell)


  Destroys pathogens
• White blood cells


  Part of the immune system
• Types of pathogens


  • Bacteria
  • Viruses
  • Fungi
• Types of white blood cells


  • Lymphocytes
  • Phagocytes
• Phagocytosis


  1. Phagocyte detects and moves towards a pathogen

  2. Phagocyte engulfs pathogen

  3. Pathogen is digested

  4. Waste product is removed
• Lymphocytes


  Some produce antibodies which destroy pathogens
• Antibodies


  Each is specific to a particular pathogen
• Red blood cells


  • No nucleus: More space for haemoglobin
  • Contains haemoglobin to bind to oxygen molecules
  • Biconcave shape to increase surface area
• Transporting Oxygen


  1. In the lungs: Oxygen diffuses into the blood at the lungs

  2. In the tissues: Haemoglobin is a protein that binds to oxygen to form oxyhaemoglobin

  3. Oxyhaemoglobin carries oxygen around in the red blood cells until the oxygen is transported to cells that require oxygen for respiration
• Components of the circulatory system


  • Heart
  • Blood vessels
  • Blood
• Pathway of blood flow

  1. Pulmonary vein carries oxygenated blood from the lungs to the left atrium

  2. Blood passes through a valve to the left ventricle

  3. Blood is pumped through the aorta and around the body

  4. Oxygen is diffused into cells around the body making the blood deoxygenated

  5. Deoxygenated blood returns through the vena cava

  6. Deoxygenated blood passes into the right atrium and down into the right ventricle

  7. Blood passes through the pulmonary artery and back to lungs to become oxygenated again
• Pulmonary vein


  Returns oxygenated blood from lungs
• Left atrium


  Passes blood from pulmonary vein to the left ventricle
• Left ventricle


  Pumps blood around body through aorta
• Aorta


  Carries oxygenated blood at high pressure around body
• Vena cava


  Returns blood from body
• Right atrium


  Passes blood from vena cava to right ventricle
• Right ventricle


  Pumps blood to lungs through pulmonary artery
• Pulmonary artery


  Carries deoxygenated blood to lungs
• Arteries


  • Carry blood away from the heart
  • Carry blood at high pressure
  • Have a thick muscular wall
• Capillaries


  • Form networks at tissues and organs
  • Carry blood at low pressure
  • Have a narrow central channel
  • Have very thin walls
  • Have a large surface area
• Veins


  • Carry blood towards the heart
  • Carry blood at low pressure
  • Have a wide central channel
  • Have a thin muscular layer
  • Have valves to prevent backflow of blood