Chapter 9 Heart

• Heart

  Pump that circulates blood through blood vessels
• Heart function

  1. Pump blood

  2. Receive blood

  3. Ventricle pumps out (strong wall)
• Semilunar valves
• Blood vessels

  • Arteries carry blood away from heart
  • Veins carry blood towards the heart
• Oxygenated blood

  Carried in arteries
• Deoxygenated blood

  Carried in veins
• Atrium

  Receives blood
• Ventricle

  Pumps blood
• All arteries carry oxygenated blood except pulmonary artery
• Septum

  Separates left and right sides to prevent oxygenated & deoxygenated blood mixing
• Left ventricle

  • Thicker wall than right ventricle
  • Contains more muscle
  • Pumps blood a long distance
  • Pumps blood at higher pressure
• Double circulatory system

  Date
• Blood passes through heart twice in one complete circuit
• Single circulatory system in fish
• Coronary arteries deliver oxygenated blood to heart muscle
• Coronary heart disease (CHD)


  Disease caused by blockage of coronary arteries
• Cholesterol deposits


  Make the lumen of the artery narrower
• Blood pressure


  Increases as artery wall becomes stiffer
• Heart attack signs: dizziness, chest pain, vomiting, sweating
• Atria contraction


  1. Atrioventricular valve open

  2. Semilunar valve closed
• Ventricle contraction

  1. Atrioventricular valve close

  2. Semilunar valve open
• Arteries


  • Wall thick, lumen narrow, elastic fibre
• Veins


  • Wall thin, lumen wide
• Capillaries


  Take oxygen, nutrients & other materials to all cells / take away cell waste
• Blood flow out of heart enters arteries at high pressure
• Blood does not flow smoothly through arteries, it pulses
• When heart muscles contract


  Blood pressure is high
• When heart muscles relax

  Blood pressure reduces
• Pulmonary circulation


  Arteries carry deoxygenated blood, veins carry oxygenated blood
• Systemic circulation


  Arteries carry oxygenated blood, veins carry deoxygenated blood
• Blood components


  • Plasma (liquid part)
  • Red blood cells (no nucleus, carry haemoglobin)
  • White blood cells (large nucleus, no haemoglobin)
  • Platelets (no nucleus, small fragments, for blood clotting)
• Lymphocytes


  Provide antibodies
• Phagocytes


  Perform phagocytosis to destroy pathogens
• Blood clotting

  1. Platelets

  2. Fibrinogen converts to insoluble fibrin

  3. Fibrin mesh traps red blood cells to form clot
• Blood flow pathway


  1. Vena cava to right atrium

  2. Right atrium to right ventricle

  3. Right ventricle to pulmonary artery

  4. Pulmonary vein to left atrium

  5. Left atrium to left ventricle

  6. Left ventricle to aorta
• Atrioventricular valves


  • Separate atria from ventricles
• Semilunar valves


  • In pulmonary artery and aorta
• Atrioventricular valves close when ventricles contract, semilunar valves close when ventricles relax
• Atria


  • Thinner muscle walls than ventricles
• Left ventricle


  • Wall 3 times thicker than right ventricle