Cardio1- CVS Physiology

  1. What dictates the opening and closing of valves?
    changes in pressure on either side of the valve
  2. What are the approximate systolic/diastolic pressures in each of the following chambers:
    • LV- 120/<12
    • RV- 25/ <5
    • Aorta- 120/80
    • PA- 25/12
    • LA- 0-12
    • RA- 0-5
  3. How can you calculate systemic BP?
    BP= CO x SVR
  4. _________ is longer than _________; therefore, the mean BP is closer to ___________.
    Diastole; systole; diastolic pressure
  5. What are determinants of systolic BP? (2)
    stroke volume, aortic stiffness
  6. Left ventricle dp/dt is the _______________ and is related to __(3)__.
    rate of LV pressure development; state of inotropy and preload and to some degree, afterload
  7. What is the correlate to afterload in the intact ventricle?
    aortic blood pressure
  8. How is inotropic state increased for the intact ventricle? (2)
    by increased SNS tone or by increased ventricular volume
  9. How is preload increased for the intact ventricle? (2)
    increase venous return, renal retention of sodium and water (increased plasma volume)
  10. 3 factors that affect SV.
    inotropy, preload, afterload
  11. How can you determine SV from an aortic time-velocity curve?
    the area under the curve= SV
  12. Aortic diastolic pressure is _________ than left ventricular diastolic pressure due to...
    higher; valve closure and systemic arteriolar vasoconstriction
  13. Global LV systolic function is quantified by the __________, which is....
    ejection fraction; SV/ EDV
  14. What is the relationship b/w shortening fraction (SF) and ejection fraction (EF)?
    SF is a linear estimate of EF obtained from M-mode echo
  15. What are approximate normal values for SF?
  16. The LA fills maximally during _________; once ___________, and the LV starts to fill.
    systole; LA pressure>LV pressure, the mitral valve opens
  17. Early diastole is associated with...
    active, energy-dependent myocardial relaxation and passive filling of the ventricles (lusitropy).
  18. Mid-diastole is associated with...
    diastasis- markedly reduced filling (only seen during normal to slow heart rates).
  19. Late diastole is associated with...
    atrial kick/active atrial contraction ot finish filling the ventricle.
  20. Active myocardial relaxation starts during ____________ and continues into ____________.
    isovolumetric relaxation; rapid filling period
  21. What is the most clinically practical method of measuring ventricular filling?
    pulsed-wave doppler recording of transmitral flow [E wave> A wave]
  22. The ___________ of the __________ graph, the stiffer the ventricle and more it resists filling.
    steeper the slope; LV pressure vs diameter curve
  23. ______________ is critically important to early diastolic filling; in mid to late diastole, _____________ becomes more important.
    Active myocardial relaxation; ventricular compliance
  24. Factors affecting ventricular filling. (6)
    venous/LA pressure, active myocardial relaxation, ventricular compliance, plasma volume, venous return, pericardial constraint
  25. Describe cardiac SNS innervation.
    beta1>>>>>>> beta2>>> alpha1
  26. Describe vascular SNS innervation.
    alpha1>>> alpha2
  27. Describe distribution of SNS vs PNS innervation of the heart.
    SNS widely innervates all heart tissues; PNS has supraventricular innervation, mainly SA and AV nodes and atrial muscle
  28. 2 factors affecting arterial BP.
    vascular resistance and cardiac output
  29. mean arterial BP =
    CO x SVR
  30. 2 factors affecting cardiac output.
    heart rate and stroke volume
  31. Factors controlling vascular resistance. (3)
    SNS efferent tone to arterioles, hormones, local vasoactive factors
  32. Factors controlling plasma volume. (1)
    renal regulation of fluid and electrolytes
  33. Venous pressure is a(n) ____________, maintaining __(3)__.
    force from the rear; hear filling, CO, and arterial BP
  34. What is the "force from the front"?
    heart literally sucks blood into the atria during systole and early diastole by creating negative pressures in the ventricles
  35. What is pulse pressure?
    the difference b/w systolic and diastolic BP
  36. What is the most important pressure responsible for tissue perfusion?
    mean pressure (closer to diastolic)
  37. What prevents pressure from sharply falling in diastole?
    elasticity of aorta and reflected waves
  38. The normal baroreceptor reflex is a(n) __________ that is stimulated by ___________.
    negative feedback loop; increased arterial BP
  39. Where are the main baroreceptors?
    carotid sinus, aortic sinus
  40. Describe the classic baroreceptor reflex arch (Marey's law of the heart).
    increased arterial BP--> increase afferent impulses to CNS from baroreceptors--> increased vagal efferent traffic (Ach)/ decreased SNS efferent traffic (NE, Epi)--> slower HR, reduced contractility, and reduced SVR (vasodilation)--> reduced BP
  41. What are the cardiac consequences of the baroreceptor reflex? (5)
    [depressed SA node] slower HR, reduced contractility, reduced CO, decreased SV
  42. What are the vascular consequences of the baroreceptor reflex? (4)
    vasodilation, reduced SVR, decreased venous return, reduced BP
  43. What does the incisura stand for on an aortic pressure curve?
    a downward notch in the curve recording aortic blood pressure that occurs between systole and diastole and is caused by backflow of blood for a short time before the aortic valve closes.
  44. What are the heart sounds, and what part of the cardiac cycle does each coincide with?
    • S4= atrial contraction following P wave (normal in large animals only)
    • S1= mitral valve closes after QRS complex b/c LV pressure exceeds LA pressure
    • S2= aortic valve closes after LV relaxes and LV pressure falls
    • S3= termination of rapid filling of LV (normal in large animals only)
  45. When during the cardiac cycle does isovolumetric relaxation occur?
    aortic valve has just shut and mitral valve has not yet opened; pressure is decreasing inside ventricle
  46. When during the cardiac cycle does isovolumetric contraction occur?
    mitral valve has just shut and aortic valve is not yet open; pressure is building in LV wall
  47. Generally explain the rises and falls in atrial pressure during the cardiac cycle.
    during active relaxation of the ventricle, atrial pressure exceeds ventricular pressure, the valve opens, and the ventricle passively fills; after the P wave, atrial kick occurs for a last small bit of ventricular filling; at this point, ventricular pressure exceeds atrial pressure and the valve closes; the atrium fills during systole
  48. When during the cardiac cycle are the atria serving as a reservoir for blood and achieving their greatest volume?
    the atria fill maximally during systole (reservoir function)- mitral valve is closed but pulmonary veins are still dumping blood into the LA
  49. When during the cardiac cycle is blood moving from the veins, across the atria, and opened AV valves as a conduit, and filling the ventricles?
    During mid-disatole, passive filling is markedly decreased but continues as the mitral valve remains open and the atrium serves as a conduit for flow from pulmonary veins to LV
  50. When in the cardiac cycle are the atria actively contracting to help fill the ventricle? How is this affected during rest and exercise (taachycardia)?
    In late diastole, after the P wave, atrial kick occurs; normally accounts for 10-20% of filling; in exercise, can be responsible for up to 50-60% of ventricular preload
  51. When is the LV wall at its thickest?
    when it has completely shortened and just before it begins actively relaxing
  52. When is the LV blood (SV) ejected most rapidly?
    peak ejection velocity= peak systolic pressure
  53. When does the aortic valve close and LV ejection end?
    aortic valve closes as LV pressure drops below that of aorta due to active ventricular relaxation
  54. When is LV afterload the highest?
    peak LV wall tension developed before the aortic valve opens
  55. What are the main determinants of myocardial oxygen consumption? (3)
    HR, myocardial tension (afterload), inotropy
  56. What are the major resistance points to the flow of blood in the normal systemic circulation?
    arterioles are the prime controllers of vascular resistance
  57. How does resistance in the pulmonary circulation differ from the systemic circulation?
    a low oxygen tension at the tissue levels causes arterioles to dilate; however, pulmonary arteries respond to low local oxygen tension by vasoconstricting (hypoxic pulmonary vasoconstriction (redirect blood to better ventilated area of lung)
  58. Contrast flow per minute between pulmonary and systemic circulations.
    both have the same flow per minute; outputs by the RV and LV are the same in a normal heart.
  59. Contrast mean arterial pressure and vascular resistance between pulmonary and systemic circulations.
    arterial pressures are lower in pulmonary than systemic circulation b/c pulmonary vessels have much lower resistance; the walls of the RV are much thinner and easier to distend--> lower pressure/resistance
  60. How is total systemic vascular resistance calculated?
    SVR= BP/CO
  61. Provide examples of disorders that can cause increased pulmonary vascular resistance? (8)
    idiopathic pulmonary hypertension, pulmonary emboli, obstructive pulmonary disease (fibrosis, emphysema), congenital heart defects, high level exercise in a horse, heartworm disease, left heart failure (backup in LA and pulmonary veins), low PAO2 (hypoxic vasoconstriction)
  62. What is cardiac index?
    relates CO from LV in one minute to body surface area,thus relating heart performance to the size of the individual
  63. What are unit for cardiac output?
  64. Where are low pressure volume receptors?
    atria and pulmonary veins, peripheral vasculature
  65. What are the general control mechanisms that regulate plasma volume.
    • ANP/BNP: cause Na+ and water loss from kidney and vasodilation
    • AngII: causes vasoconstriction
    • Vasopressin: causes vasoconstriction and renal water retention in excess of Na+
    • Aldosterone: causes renal water and Na+ retention and K+ loss
  66. When in the cardiac cycle does maximal coronary blood flow occur and why?
    during early diastole, when the heart is relaxed, myocardial wall tension is minimal and coronary vessels are not compressed.
  67. Describe the starling forces responsible for flow of blood through capillaries and flow of serum from capillary to interstitium.
    • capillary oncotic pressure: (proteins) pulls fluid into capillaries
    • capillary hydrostatic pressure: (BP) pushes fluid out of capillaries
    • interstitial oncotic pressure: pulls fluid out of capillaries
    • interstitial hydrostatic pressure (negative): pulls fluid out of capillaries
  68. Why might pulmonary edema occur? (4)
    increased BP (hydrostatic pressure), decreased capillary oncotic pressure, increased interstitial oncotic pressure, venous obstruction--> increased hydrostatic pressure
  69. How is pulmonary edema prevented in health?
    lymphatic system drains small amount of fluid that is constantly being pulled out of the vessels--> returns fluid to systemic venous circulation
  70. What factors cause blood to return to the heart? (7)
    normal plasma volume, sympathetic stimulation--> peripheral vasoconstriction, venous pressure (force from behind), negative pressure in heart (force from the front), venous valves prevent backflow, muscular compression of veins by skeletal m., gravity hydrostatic pressure
Card Set
Cardio1- CVS Physiology
vetmed cardio1