Heartbeat 1 -

A single heartbeat, often referred to as a cardiac cycle, is a sophisticated two-part pumping action that occurs in approximately one second. This process is governed by the heart's internal electrical system, led by the , commonly known as the natural pacemaker . The cycle consists of two primary phases:

For a healthy adult at rest, a normal heart rate typically ranges between . This rate is dynamic and adjusts based on factors such as physical activity, stress, and emotions like fear, which triggers the release of adrenaline . Interoception: Perceiving the Pulse heartbeat 1

A single, complete cycle of contraction and relaxation. A single heartbeat, often referred to as a