The Cardiac Cycle

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  • Created by: emilyowl
  • Created on: 10-05-16 13:36
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  • CARDIAC CYCLE
    • RELAXATION OF THE HEART..{diastole}
      • Blood returns to the heart atria
        • Pulmonary vein - from lungs
        • Vena cava - from body
        • Atria pressure exceeds ventricular pressure
          • Atrioventricular valves open
            • Blood passes into the ventricles
              • Relaxation of ventricle walls means they can recoil
                • Reduces pressure in ventricle
                  • Pressure in ventricle is lower than in aorta and pulmonary artery
                    • Semi - lunar valves close
                      • 'DUB'
      • Atria and ventricles are relaxed
    • CONTRACTION OF ATRIA........... {atrial systole}
      • Contraction of atrial walls
        • Forces remaining blood into ventricles from atria
          • Relaxed ventricle walls
            • Muscles of ventricle walls stay relaxed
      • Relaxed ventricle walls
        • Muscles of ventricle walls stay relaxed
    • CONTRACTION OF VENTRICLES... {ventricular systole}
      • Ventricles fill with blood
        • Walls contract simultaneously
          • Increases blood pressure in them
            • Forcing shut the atrioventricular valves
              • Prevents backflow into the atria
              • 'LUB'
              • Pressure rises further
                • Pressure exceeds the aorta and pulmonary artery
                  • Blood is forced into aorta and pulmonary artery
                    • The thick muscular walls forcefully  contract
                      • Creates high pressure necessary to pump blood around the body
                        • Thick wall of left ventricle
                          • Pumps blood to the extremities of the body
                        • Thinner wall of right ventricle
                          • Pumps blood to the lungs

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