Physiology of the heart

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Physiology of the heart
2013-01-06 01:30:04
Chapter 19

Nursing review
Show Answers:

  1. What vital role does the cardiovascular system maintain?
    continuous and controlled movement of blood through capillaries
  2. Cardiovascular system has...
    ...numerous control mechanisms
  3. What is hemodynamics?
    A collection of mechanisms that influence the dynamic circulation of blood
  4. What is essential for healthy survival?
    Circulation of different volumes of blood per minute
  5. Circulation control mechanisms must accomplish which two functions?
    • Maintain circulation
    • Vary volume and distribution of the blood circulated
  6. The conduction system of the heart is composed of which four major structures?
    • 1. Sinoatrial (SA) node
    • 2. Atrioventricular (AV) node
    • 3. AV bundle (bundle of his)
    • 4. Subendocardial branches (Purkinje Fibers)
  7. The SA node is responsible for which two functions?
    • Initiating heartbeat
    • Setting heart's pace
  8. As the                   enters the AV node from the right atrium, its conduction         to allow complete contraction of both atrial chambers before the impulse reaches the ventricles
    Action potential; slows
  9. The P wave is created by which conduction point?
    SA node
  10. The QRS complex is created by which conduction point?
    bundle of HIS
  11. What does a heart block mean?
    That the signal to the ventricles is blocked
  12. What does the P wave represents?
    Depolarization (contraction) of the atria
  13. What does the QRS complex represents what?
    The depolarization (contraction) of the ventricles and repolarization (relaxation) of the atria
  14. What does the T wave represent?
    The repolarization (relaxation) of the ventricles
  15. What does the U wave represent?
    the repolarization (relaxation) of the papillary muscle (Purkinje fibers)
  16. How is the U wave represented on the ECG report?
    as a tiny "hump" at the end of the T wave
  17. What are some characteristics of the U wave?
    • Absent or small U waves are usually considered normal
    • U waves may be a sign of hypokalemia or too much digoxin
  18. What is a cardiac cycle?
    A complete heart beat
  19. What does systole mean?
    a contraction
  20. What does diastole mean?
    a relaxation phase
  21. What is the atrial systole?
    The cycle that begins with the P wave of the ECG, which triggers atrial contraction
  22. What are the steps of atrial systole in the cardiac cycle?
    • Atria contraction creates a pressure gradient that pushes blood out of atria into relaxed ventricles
    • Due to pressure gradients, AV valves are open and SL valves are closed
    • Ventricles are relaxed and filling with blood from atria
  23. The cardiac cycle is divided into...
    ...time intervals
  24. Isovolumetric ventricular contraction makes which heart sound?
    The first; the "lub" sound
  25. Isovolumetric ventricular relaxation makes which heart sound?
    The second sound; the "dub" sound
  26. What is the Isovolumetric ventricular contraction?
    Onset of the ventricular systole that coincides with the R wave.
  27. When does the Isovolumetric ventricular contraction occur?
    Between the start of the ventricular systole and the opening of the SL valves
  28. What occurs during the ejection phase of the cardiac cycle?
    SL valves open and blood is ejected
  29. What is rapid ejection?
    Initial short phase marked by an increase in ventricular and aortic pressure and in aortic blood flow
  30. What is reduced ejection?
    decrease in ventricular volume
  31. When does Isovolumetric ventricular relaxation begin?
    At the beginning of ventricular diastole
  32. When does Isovolumetric ventricular relaxation occur?
    between closure of the SL valves and opening of the AV valves
  33. What is passive ventricular filling?
    ventricular relaxation which causes blood to rush into relaxed ventricles, which returns venous blood
  34. What is diastasis?
    Slow ventricular filling lasting approx. 0.2 second; characterized by a gradual increase in ventricular pressure and volume
  35. What occurs when passive ventricular filling is done?
    The cardiac cycle begins again
  36. The systolic sound is...
    the first heart sound from ventricles contracting and AV valves closing
  37. The diastolic sound is...
    ...a short sharp sound and the SL valves closing
  38. Blood flows because...
    ...a pressure gradient exists between different parts of its volume
  39. Pressure is basically                             when it reaches the capillaries
  40. What does P1-P2 represent?
    A pressure gradient with P1 representing the higher pressure and P2 the lower pressure
  41. What is the arterial blood pressure represent?
    The amount of blood being pumped and at what rate. The higher the volume of blood= the higher the blood pressure
  42. What is cardiac output (CO)?
    the volume of blood pumped out of the heart per minute
  43. What determines cardiac output?
    Stroke volume and heart rate
  44. What determines stroke volume?
    Volume pumped per heartbeat
  45. CO (volume/ min) = SV (volume/ beat)x HR (beats/min)
  46. What is Starling's law of the heart?
    The more stretch the stronger the contraction. The amount of blood in the heart determines the amount of stretch placed.
  47. What is contractility?
    strength of contraction. Influenced by chemical factors
  48. Which chemical can influence the neural system?
  49. Which chemical can influence the endocrine system?
  50. Contractility can also be triggered by...
    stress and exercise
  51. What is the ejection fraction (EF) ratio?
    the ratio of stroke volume (SV) to end-diastolic volume (EDV)
  52. What does the ejection fraction represent?
    The amount of blood in ventricle during contraction / amount of blood in ventricle after ejection
  53. What is the normal range for healthy adults?
    at least 55%
  54. Where is the carotid sinus reflex located?
    at the beginning of the carotid artery
  55. Where do the sensory fibers from the carotid sinus baroreceptors run?
    Through the carotid sinus nerve