Generally, when we think of calcium, we think of a hard substance which helps keep teeth and bones strong. But calcium plays a vital role in helping our heart to beat.
Calcium in the cardiac cell is in liquid form, so it effectively flows into the cardiac region. The process of calcium helping our hearts to beat is extremely complex, but basically the calcium flows into the cardiac cell in between heartbeats. It then triggers an electrical wave to activate all the heart muscle cells so that they contract in unison: and the result is a heartbeat.
As we grow older the calcium pump becomes less effective, which is why some older people get out of breath more easily then they did when young, particularly when exercising.
Sometimes the role of calcium within the heartbeat function is decribes as the body's natural 'pacemaker' since it kickstarts the heart to beat.