Cardiovascular System

  1. Why closed circulatory system?
    no openings to leave the vessels
  2. systematic circulation (path)
    left ventricle - aorta - arteries, arterioles, capillaries

    capillaries - collected into venules - veins - superior and inferior vena cava - right atrium
  3. pulmonary circulation
    right ventricle - pulmonary arteries - arteries - capillaries in lungs:

    venues - veins - pulmonary veins - left atrium [heart]
  4. Image Upload 1
  5. Is the heart a muscle?
  6. systole v. diastole
    • systole = ventricles contract
    • diastole = relaxation of heart and then contraction of aorta
  7. how is the blood propelled?
    hydrostatic pressure
  8. how is hydrostatic pressure initiated?
    contraction of the heart
  9. how is the rate of contraction controlled?
  10. does ANS initiate contraction?
  11. How does it contract then?
  12. How does it contract? (method)
    sinoatrial node (SA) in right atrium contracts at regular intervals
  13. How is the contraction spread?
    via electrical synapses from gap junctions
  14. How is contraction slowed down?
    parasympathetic vagnus nerve
  15. Where is the Action Potential spread to next?
    atrioventicular node (AV node)
  16. what happens when AP reaches AV node, before ventricles can contract?
    AV node contracts slower, allowing atria to contract and squeeze contents into ventricles
  17. So, AV node does what to contraction of ventricle in heart?
    delays contraction -

    pauses for a fraction of a second
  18. Where is Action Potential spread down?
    bundle of His
  19. What is the bundle of His?
    wall separating ventricles
  20. What are Purkinje fibers?
    branches out AP through gap junctions throughout the cardiac muscles
  21. advantages of purkinje fibers
    allows for more unified, stronger contraction
  22. Are arteries elastic?
  23. What does that say about arteries?
    they stretch when filled with blood
  24. What allows them to stretch?
    wrapped by smooth muscle
  25. How is the smooth muscle that allows for elasticity controlled?
    sympathetic nervous system
  26. large arteries (muscle and sympathetic control)
    have less smooth muscle

    less affected by sympathetic innervation
  27. arterioles
    very small
  28. Are they wrapped by smooth muscle?
  29. What does constriction and dilation of arterioles control?
    regulate blood pressure
  30. capillaries (relative size)
  31. capillary function
    intermediate for nutrient and gas exchange with tissue
  32. methods for material to cross capillary walls:
    • 1. pinocytosis
    • 2. diffusion or transport (membrane)
    • 3. mvmt. through pores
    • 4. mvmt. through space between cells
  33. when blood flows into capillary what is greater hydrostatic or osmotic pressure?
    hydrostatic pressure
  34. So in what direction is the net fluid flow?
    out of the capillary
  35. What happens when fluid flows out?
    hydrostatic pressure drops from arteriole to venule -

    osmotic pressure is greater at the venule end
  36. So in what direction is net fluid flow now?
    into capillary
  37. Image Upload 2
    fluid that is not reabsorbed is sent to the lymph
  38. What percentage of fluid is lost in the process
  39. venules and veins
    similar to arterioles and arteries
  40. difference
    larger lumen
  41. in systematic circulation what is the main function of veins and venues?

    hold about 64% of blood in body at rest
  42. How much blood do arteries, arterioles, and capillaries hold
    about 20%
  43. artery v. veins (direction of blood flow)
    artery = caries blood away from heart

    vein = carries blood toward heart
  44. velocity of blood flow
    inversely proportional to cross-sectional area
  45. cross sectional area - greater in capillaries, arteries, or veins?
    greatest in capillaries
  46. so blood moves slowest through....
  47. flow rate of blood in capillaries
    constant rate
  48. blood pressure is greater where?
    increases near the heart

    decreases near the capillaries
Card Set
Cardiovascular System
Bio MCAT Cardiovascular System