USMLE

Heart

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Cardiovascular
  1. Cardiovascular Overview
  2. CO2 Transport
  3. Heart
  4. Cardiac Impulse
  5. Blood Pressure
  6. Arteries and Arterioles
  7. Veins and Venules
  8. Capillaries
  9. Circulation
  10. Blood
  11. Hemoglobin
  12. Blood Clotting
  • Topic Anchor: Heart 
    • Structure:
      • 4 chambers: right atrium, right ventricle, left atrium, left ventricle
        • Blood flows from atrium to ventricle
        • Left ventricle thicker/more muscular than right ventricle
          • Left ventricle must supply systemic circulation (high pressure)
          • Right ventricle supplies pulmonary circuit (low pressure)
      • 4 valves:
        • Atrioventricular valves: prevent backflow into atria
          • Tricuspid valve: between right atrium and ventricle
          • Mitral/bicuspid valve: between left atrium and ventricle
        • Semilunar valves: prevent backflow into ventricles
          • Pulmonary semilunar valve: between right ventricle and pulmonary vein
          • Aortic semilunar valve: between left ventricle and aorta
      • Heartbeat (Cardiac Cycle)
        • Diastole:
          • Ventricles relax
            • Lowest pressure of cardiac cycle
          • Atrioventricular (tricuspid and mitral) valves open
            • Blood flows from atria to ventricles (filling)
        • Systole:
          • Ventricles contract
            • Highest pressure of cardiac cycle
          • Semilunar (aortic and pulmonary) valves open
            • Blood pumped out of heart