38 This figure shows electrical activity of the SA node indi

38. This figure shows electrical activity of the SA node indicate(s) when calcium enters the myocytes. A. 1 and 2 B. 2 and 3 C. 3 D. 2 E. 1 39. This figure shows an action potential in a ventricular cardiocyte. indicates when sodium channels are fully open. A. 1 B. 3 C. 2 E. 4

Solution

38. D (2)

39. C (2- ventricular systolic)

40. B (depolarize slow)

41. E (arrhythmia)

42. D (40- 50 bpm)

43. C (sarcoplasmic reticulum)

44. B (immediately after P wave)

45. A (the P wave)

46. C (Ca²⁺)

47. B (prevents tetanus)