section 5 - blood and organs

• Blood components


  • Plasma
  • Platelets
  • Red blood cells

  
• Plasma


  Plasma components are substances carried in plasma e.g. Vitamins and minerals
• Platelets


  Help in blood clotting
• Red blood cells


  To carry oxygen
• Structure and function of red blood cells


  • Biconcave shape so a large surface area for diffusion of oxygen
  • No nucleus so more space for haemoglobin to carry oxygen
• Anaemia is iron deficiency
• Symptoms of anaemia


  Shortness of breath and tiredness because there is less iron to make haemoglobin in red blood cells
• Less red blood cells due to anaemia


  Less energy produced causing symptoms of tiredness
• At high altitudes there is lower oxygen levels


  Athletes train there because they produce more red blood cells to carry oxygen
• When athletes return to normal altitudes


  They are more efficient at transporting oxygen in red blood cells to muscle cells needed for aerobic respiration
• Types of white blood cells


  • Phagocytes
  • Lymphocytes
• Phagocytes


  Engulf pathogens and are large
• Lymphocytes


  Produce antibodies that stick to antigens on pathogens to destroy them
• Vaccination


  1. Insert dead or inactive pathogens into the body

  2. Causes lymphocytes to produce antibodies to destroy them

  3. Produces memory cells to recognize pathogens

  4. Body will produce more antibodies and faster

  5. This is a secondary immune response
• Blood vessels


  • Arteries
  • Veins
  • Capillaries
• Arteries


  • Elastic fibres and thick walls
  • Small lumen
  • High pressure
• Veins


  • Elastic fibres and thin walls
  • Large lumen
  • Low pressure
  • Valves to prevent backflow of blood
• Capillaries


  • Thin wall-only one cell thick
  • Very small lumen
  • Low pressure
  • Permeable wall
• Capillary adaptations for exchange


  • Permeable walls for diffusion
  • Walls are one cell thick so a short diffusion distance
• Summary of blood flow in heart


  1. Right (deoxygenated): blood comes from the body in the vena cava, right atrium, past the tricuspid valve, right ventricle, semilunar valve, pulmonary artery to the lungs

  2. Left (oxygenated): blood comes from lungs in pulmonary vein, left atrium, bicuspid valve, left ventricle, semilunar valve, aorta to the body

  
• Coronary heart disease (CHD) is when coronaries arteries become blocked with plaque (fat) causing a lack of oxygen and then a heart attack
• Risk factors for CHD


  • Diet high in saturated fat
  • High blood pressure
  • Inactivity
  • Smoking
• Roles of the kidneys


  • Removal of urea
  • Adjustment of ion levels
  • Adjustment of water content

  
• Kidney structure


  • Glomerulus
  • Bowmans capsule
  • Proximal convoluted tubule
  • Loop of Henle
  • Distal convoluted tubule
  • Collecting duct

  
• Glomerulus


  • Blood from renal artery flows through
  • Ultrafiltration (water, urea, ions and glucose). Filtered liquid is glomerular filtrate

  
• Proximal convoluted tubule


  Glucose is reabsorbed (by active transport) so it can be used in respiration and not excreted
• Collecting duct


  Water reabsorbed by osmosis
• If a person is dehydrated


  The pituitary gland releases ADH which makes the collecting ducts more permeable so more water is reabsorbed into the blood and there is less urine