Cardiac cycle

The recurrent sequence of contraction and relaxation during a heartbeat. Electrical activity, mechanical contraction and sensory afferent signals have related but different timings.

The relaxation and filling phase of a cardiac cycle. In cardiac-phase experiments it provides a comparison period with different baroreceptor signalling.

The contraction phase of a cardiac cycle; ventricular systole includes ejection of blood. Timing a stimulus to systole can change its relation to cardiovascular afferent signals.