29 This figure shows the principal coronary blood vessels Wh

29. This figure shows the principal coronary blood vessels. Which one is the left coronary artery (LCA)? B. 8 C. 5 D. 3 E. 1 will cause a more severe myocardial infarction (MI) 30. Obstruction of the than the obstruction of any of the others A. left marginal vein B. left coronary artery (LCA) C. posterior interventricular vein D. anterior interventricular branch E. circumflex branch

Solution

29. D. 3

30. B. left coronary artery

31. A. cardiac muscle fibers have striations

32. C. Sinatrial (SA) node.

33. B. . The tendinous cords.

34. e. They have about the same endurance as skeletal muscle fibers.

35. SA node, AV node, AV bundle, Purkinje fibers, cardiocyte in LV

36. A. Na+ inflow

37. E. slow CA2+ channels