USMLE

Circulation

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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
  • Circulation
    • Path of blood flow: Atriumventriclearteryarteriolecapillariesvenulesveins → other atrium
    • Pulmonary (lung) circuit
      • Starts in right atrium and ventricle
      • Pulmonary arteries carry blood to lung to be oxygenated
        • Deoxygenated (low O2)
        • High CO2
      • Pulmonary veins return oxygenated blood to heart (left atrium)
      • Low pressure system
        • Right ventricle has thinner walls than left ventricle, since it needs to generate less pressure
    • Systemic (body) circuit
      • Starts in left atrium and ventricle
      • Arteries carry blood to body tissues to supply nutrients and oxygen
        • Oxygenated (high O2)
        • High CO2
      • Veins carry deoxygenated blood back to heart
        • Empty into (superior and inferior) vena cavae, which empties into right atrium
      • High pressure system
        • Left ventricle has thicker/stronger muscular wall, as systemic circulation has higher pressure