Heart

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  • Created by: emma
  • Created on: 17-03-14 21:05
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  • Heart
    • Structure
      • Deoxygenated blood returns from body via vena cava and enters right atrium
        • Passes through right atrio ventricular valves in to right ventricle
          • Then passes into the pulmonary artery via the semi lunar valve
      • Oxygenated blood returns from lungs via the pulmonary vein and enters left atrium
        • Passes through left atrio ventricular valve into left ventricle
          • Then passes into aorta via semi lunar valve
    • Pressure
      • Blood enters atrium which increases pressure in atrium to be greater than in ventricle
        • Atrio ventricular valves open
          • Blood enters Ventricle which increases pressure in ventricle to be greater than in atrium
            • Atrio ventricular valves close
      • Ventricles contract increasing pressure in ventricle to be greater than in aorta/ pulmonary artery
        • Semi lunar valves open
          • Ventricle relaxes so pressure in ventricle less than aorta/ pulmonary artery
            • Semi lunar valves close
    • Cardiac cycle
      • Sino atrial node sends out electrical impulse across right atrium wall
        • Causing it to contract
      • Non conducting fibres prevents electrical impulse passing into ventricles
        • Allow time for atria to empty
      • Atrio ventricular node sends electrical impulse down bundle of His
        • Cuasing ventricles to contract
    • Cardiac output
      • CO=SV*HR
        • Heart rate
          • number of cardiac cycles per minute
        • Stroke volume
          • Volume of blood expelled from the left ventricle in one heart beat
        • Cardiac output
          • Volume of blood expelled from left ventricle in one minute
    • Atheroma
      • Cholesterol builds up
        • Gathers under endothelium of artery
          • Atheroma causes blood clots
            • Blocks coranory
              • Reduces O2 and glucose to cells so they cant respire and die
    • Thrombosis
      • Plaque ruptures and triggers blood clott
        • This blocks the artery
    • Aneurysm
      • Artery becomes blocked blood flow through area is restricted
        • Pressure builds up
          • Cause artery wall to weaken and it starts to buldge outwards

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