Challenge Your Exam Readiness With Our Free ATI TEAS Practice Questions

The atrioventricular (AV) valves—the tricuspid (right side) and mitral/bicuspid (left side)—separate atria from ventricles. During ventricular systole (contraction), pressure rises in the ventricles and forces these valves closed, preventing retrograde flow into the atria. Chordae tendineae and papillary muscles stabilize valve leaflets to avoid prolapse. In contrast, semilunar valves (pulmonary and aortic) prevent backflow from the great arteries into the ventricles during diastole; they do not separate atria from ventricles. The SA node (A) initiates the heart’s intrinsic pacemaker activity and sets rate; it has no mechanical role in preventing backflow. Purkinje fibers (D) rapidly conduct depolarization through the ventricles to coordinate contraction. TEAS emphasizes matching structure to function: AV valves = stop backward flow toward atria; semilunar valves = stop backward flow from arteries; conduction tissues (SA node, AV node, bundle branches, Purkinje) coordinate timing rather than physically controlling flow.