1.   Foods and fluids are mixed in the stomach by its muscular contractions.

2.   The atria set the rhythm for the muscular contractions we call the heartbeat, and the ventricles supply the horsepower.

3.   There were times when the drumming had the effect of a heartbeat, the muscular contraction of one sonic chamber releasing itself into the motion of another.

4.   The controversial class of drugs works by blocking calcium penetration in cells, which relaxes the muscular contraction of the arterial wall.