Interactive Biology · Grade 7
Scroll down to explore the organ that never stops — beating about 100,000 times every single day of your life.
The good and the brutal
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Beats ~100,000 times a day, every day, without a single break for your entire life.
The SA node generates its own electrical signal — no brain required to keep it beating.
Output can jump 5× during exercise in seconds, delivering exactly the oxygen muscles need.
Pumps blood through 60,000 miles of blood vessels — enough to circle Earth twice.
Heart disease kills more people worldwide than any other cause — one attack every 40 seconds in the US.
Adult heart muscle cells barely divide. Damage from a heart attack is largely permanent.
Plaque can build inside arteries for decades with zero symptoms — until the first heart attack.
Chronic stress floods the body with cortisol, which stiffens arteries and weakens the heart muscle over time.