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  • The Heart
    • Structure of the heart
    • If the heart doesn't work properly, tissues and cells won't get enough oxygenated blood so the tissue can't respire, & the supply of blood will be less. This will cause a person to become breathless & fatigued.
    • The heart is divided into 2 halves
      • Blood flows in one direction through each half of heart
        • Valves between the atria and ventricles close to stop back flow of blood when ventricles contract
          • Valves at bottom of pulmonary artery and aorta to prevent back flow of blood to ventricles when they relax.
            • Tendons attached to valves to stop them from being pushed inside out
    • Cardiac Muscle
    • Coronary arteries on surface which supply heart muscle with oxygen and glucose so it can continue contracting and pumping blood.
    • Valves
      • One way valves
        • Semi-lunar
        • Tricuspid
          • These are attached to wall of heart to prevent them from being turned inside out
            • Semi-lunar
            • Biscuspid
            • They prevent blood flowing back into ventricles when they stop contracting.
              • Stop blood flowing into atrium
        • Biscuspid
    • Passage of Blood through the heart
      • 1) Vena Cava carries blood from organs of body to right atrium
        • 2) Blood then passes through a valve to right ventricle
          • 3) Right ventricle contracts and so pumps blood through valve into pulmonary artery
            • 4) The pulmonary artery passes blood to lungs where it is oxygenated
              • 5) Pulmonary vein carries blood from lungs to left atrium
                • 6) Oxygenated blood passes through valve into left atrium
                  • 7) Left ventricle contracts and pumps blood through valve into aorta
                    • 8) Aorta carries blood from heart to organs of body
      • How does blood travel from right ventricle to left atrium?
        • Muscle of right ventricle contracts and pumps blood through valves of pulmonary artery into the lungs
          • Blood then leaves the lungs, passing into the pulmonary vein, re-entering the heart in the left atrium
    • Cardiac Cycle
      • The cardiac cycle is the series of events that occur when the heart beats
      • 1) All four chambers are relaxed and partially filled with blood
        • 2) ATRIAL SYSTOLE- atrial contract so relaxed ventricles completely fill with blood
          • 3) ATRIAL DIASTOLE- continues until next cycle begins
            • 4) VENTRI-CULAR SYSTOLE
    • Effect of exercise on heart beat rate
      • Heart rate increases to supply muscles with more oxygen and glucose for respiration
      • The lower the heart beat rate the fitter the person


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