Heartbeat
A heartbeat was the sound that a heart made when it pumped blood through the circulatory system.

In 2266, during Harry Mudd's formal hearing, the heartbeat rate of the men present in 's briefing room became more rapid due to his lovely companions. This, among other symptoms, was detected when James T. Kirk asked Enterprise's computer to go to sensor probe. Embarrassed, he asked the computer to strike it from the record. ()

Craft described the pulse-rigger's hydropulse as being similar to that of a heartbeat. ()

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Physiology