Answer to Question #58393 in Human Anatomy and Physiology for sue

Question

Which action leads to the closure of the left atrioventricular valve?

a. Contraction of the right atrium

b. Contraction of the right ventricle

c. Contraction of the left ventricle

d. Relaxation of the right atrium

e. Relaxation of the left ventricle

Answer 1

c. Contraction of the left ventricle

The AV valves close when intraventricular pressure exceeds atrial pressure. Ventricular contraction also triggers contraction of the papillary muscles with their chordae tendineae that are attached to the valve leaflets. This tension on the the AV valve leaflets prevent them from bulging back into the atria and becoming incompetent (i.e., “leaky”). Closure of the AV valves results in the first heart sound. This sound is normally split (~0.04 sec) because mitral valve closure precedes tricuspid closure.