Cardiac Cycle: The Heart’s Rhythmic Symphony

The heart, a remarkable organ, orchestrates a rhythmic symphony that sustains life. Central to this rhythm is the cardiac cycle, a sequence of events that ensures blood flows seamlessly throughout the body. Each beat of the heart represents a complete cardiac cycle, which consists of two primary phases: systole and diastole. During systole, the heart's ventricles contract, propelling oxygen-rich blood into the arteries. Following this, diastole occurs as the heart muscles relax, allowing the chambers to fill with blood in preparation for the next cycle.

This cycle is a precisely timed process, governed by the heart's electrical conduction system. The sinoatrial (SA) node, often referred to as the heart's natural pacemaker, initiates the electrical impulses that trigger each heartbeat. These impulses travel through the atria, causing them to contract and push blood into the ventricles. The impulses then reach the atrioventricular (AV) node, slowing momentarily to allow the ventricles to fill before they contract.

The cardiac cycle repeats this process approximately 60 to 100 times per minute in a healthy adult, maintaining the vital flow of blood and ensuring that every cell in the body receives the oxygen and nutrients it needs to function.