The heart beats approximately 100,000 times a day, totaling around 3 billion times throughout an average lifetime. With each heartbeat, blood is pumped to the lungs to pick up oxygen, then flows into all cells to deliver nutrients and oxygen while removing waste products.
While at rest, the heart typically beats between 60 and 100 times per minute. Healthy individuals may have a resting heart rate of 40 to 50 beats per minute, but it can increase when exercising, stressed, or angry. Maximum heart rate is estimated by subtracting age from 220, so a 13-year-old’s peak rate would be 207 beats per minute.
The heart is composed of millions of muscle cells that contract in synchrony to ensure proper blood circulation continuously.
Each heartbeat consists of two phases and produces the rhythmic sound “Lubdub.” This rhythmic pattern arises from the coordinated pumping of blood by the heart’s four chambers.
Each beat initiates in the heart’s upper chambers, the right and left atriums, where hypoxic and oxygenated blood is received, respectively.
After filling the atriums, blood moves down into the muscular ventricles (right and left) below them. Closure of valves prevents backward blood flow, creating the “lub” sound. Subsequently, the ventricles contract, pumping blood to the lungs and the body, and valve closure produces the “dub” sound.
Despite varying speeds, the heart’s rhythm always follows the same order of contraction.
Although the brain provides some input, the heart functions independently. The sinoatrial node, commonly known as the SA node or natural pacemaker, coordinates the heart’s rhythm.
The SA node, the heart’s natural pacemaker, controls the firing rate of electrical signals into the heart’s upper chambers, initiating the heart’s contraction.
These signals move to the AV node, an electric transfer station between the heart’s upper and lower chambers. The AV node transmits signals to the ventricles, prompting muscle contractions to pump blood throughout the body.
In summary, every heartbeat occurs about 60 times per minute, continuously from birth to death.
Source: www.snexplores.org
