S₂ Is

Question

S₂ is
A) caused by the closure of the AV valves at the beginning of ventricular contraction.
B) the second heart sound.
C) the heart sound caused by the sliding of actin and myosin.
D) All of the above are true.

Accepted Answer

S₂ is the second heart sound, which is caused by the closure of the semilunar valves at the end of ventricular contraction. Option A is incorrect as it refers to the first heart sound (S₁), which is caused by the closure of the AV valves. Option C is incorrect as it describes the mechanism of muscle contraction in skeletal muscle, not the heart. Option D is incorrect as only option B is true.