28. When a cardiac muscle action potential is present, but there is insufficient calcium to result in mechanical action (muscle contraction), the result is described as:

25. A dilatation at the bases of aorta & pulmonary trunk that presumably provides space for the semilunar valve apparatus when opened is called the:

30. A fixed, split S-2 can be due to:

26. Final ventricular filling during the very end of diastole coincides with: .

47. Name the valve:

31. Name the chamber:

42. Is this the wall of the left ventricle or the right ventricle?

43. Name the wall:

37. Name this valve:

39. Name this valve: