Inquiry into Life 14th Edition by Sylvia Mader,Michael Windelspecht

تمرين 8

Choose the best answer for each question.
The "lub," or first heart sound, is produced by closing of the
A) aortic semilunar valve.
B) pulmonary semilunar valve.
C) tricuspid valve.
D) bicuspid valve.
E) both AV valves.