PE revision THE HEART

  • Created by: M.Cowdrey
  • Created on: 23-01-17 19:20
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  • The Cardiovascular system
    • Journey of Blood to Heart
      • De- oxygenated blood returns from the body to the right atrium via the superior and inferior vena cava
        • At the same time oxygenated blood returns from the lungs to the left atrium via the pulmonary veins.
          • The Bicuspid and Tricuspid valves are forced to open by the increase in pressure in both atria and blood enters the lower chambers of the heart called the left and right ventricle.
            • The muscular walls of the ventricles contract, blood in the right ventricle is forced out through the semi-lunar valve into the pulmonary artery.
              • Blood left in the left ventricle is forced through the semi-lunar aortic valve and into the aorta which branches into many arteries to transport oxygenated blood around the body.
    • Cardiac Tissue is myogenic (generates its own electrical impulse)
      • The cardiac impulse orientates from the Sinoatrial Node ( SA) located in the muscular wall of the right atrium.
        • SA Node emits an electrical impulse which spreads rapidly through the atria causing them to contract
          • The impulse then arrives at AV node, which delays the transmission of the impulse to the ventricles for 0.1 seconds.
            • After the delay,AV node sends signal down septum via the bundle of his, through the muscular walls of the ventricle via the purkinje fibres causing them to contract.
    • Neural and Hormonal control of the heart
      • Proprioreceptors and mechanoreceptors- detects movement in muscles
      • Chemorecptor- detects changes in PH in the blood
      • Baroreceptors- stretch receptors in the aorta, vena cava and in the blood vessels
      • Adrenaline and Noradrenaline- Increases HR, Constricts Blood vessels, stimulates breakdown of glycogen
      • Acetylcholine- hormone released decreasing HR
    • Cardiac Control Centre
      • Sympathetic System-cardio-acceleratory centre increases HR
      • Parasympathetic system- cardio inhibitory system- decreases HR
    • Cardiac dynamics
      • Stroke Volume-volume of blood pumped out of the heart per minute
        • Bradycardia- reduction of resting heart rate to below 60bpm following endurance training
          • Cardiac Output= SV x HR
    • Key terms
      • Vasoconstriction- narrowing of the arterioles supplying the organs such as the intestines
      • Vasodialation- opening of the arteriole, supplying actively working muscles
      • Vascular Shunt- Redistribution of blood flow during exercise.


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