5 Fun Facts About Your Heart, the Amazing Cardiac Muscle

Did you know that your heart is one of the busiest organs in your body? It works nonstop around-the-clock to pump blood all around from head to toe. This is true for babies, kids, and grown-ups. Here are 5 fun facts about your amazing heart.

Cardiac Muscle Anatomy

Your Heart is Made of Muscle

Yes, the one-and-only cardiac muscle in the body!

The special heart muscle is designed to squeeze (contract) and pump out oxygen-rich blood to all of your blood vessels. When the heart muscle relaxes, it gets filled-up with old blood from your body.

Even though you can’t see your heart muscle, it still needs exercise to stay strong and healthy. How does your heart get a good work out? By doing fun activities that speed up your heart and get you to sweat. Every day of the week, try to stay active with games like tag, soccer, or basketball; go for a run; or take dance lessons.

Your Heart Is Like a House With Rooms

heart anatomy - labeled diagram of the inside

Just like a house, your heart is organized into different sections. Your heart house is made up of these main parts:

  • 4 Rooms:
    • 2 Atria “upstairs” (right atrium, left atrium)
    • 2 ventricles “downstairs” (right ventricle, left ventricle)
  • Walls that separate the right and left sides of the heart
  • Valves that act like doors between the top atria and bottom ventricles
  • Blood vessels, the plumbing system for blood flow
  • Nerves, the heart’s electricity that powers each heartbeat

You Can Hear the Doors (Valves) Shut

Lub-dub, lub-dub. If you listen to a heart with a stethoscope or lean your ear against someone’s chest, the “boom-boom” sound is caused by the heart valves closing.

Your Heart Works With Other Organs

Teamwork is always happening in your body! Your nervous system and endocrine system both affect the pace of your heart.

Brain and the Nervous System Anatomy for Kids

Nervous System

The bottom part of your brain – the brainstem – controls your heart rate.

Through your spinal cord and nerves, it sends electrical signals to tell your heart to slow down during rest and speed up during exercise, stress, danger, and excitement.

Endocrine System - Thyroid Gland Anatomy for Kids

Endocrine System

Your endocrine glands also make hormones that affect your heart rate.

The thyroid gland sends out thyroid hormone, which causes the heart to beat harder and faster.

The adrenal gland sends out adrenaline (epinephrine) which revs up your heart rate.

Your Heart is the Same Size of Your Fist

Like your hands and the rest of your body, the size of your heart changes as you grow. Close your hand into a fist; this is about the same size as your heart right now!

Tiny Baby Hearts are the Fastest

Picture a walnut: that’s about the same size as a baby’s heart. Even though newborn babies have teeny tiny hearts, their cardiac muscle is mighty and fast. In fact, newborns have the fastest heart rate compared to kids and adults of all other ages.

When you grow up, your heart gradually slows down.

Cardiovascular System in a Baby - Anatomy for Kids

Watch This Cool Video of a Beating Heart!

This realistic heart model was created by a computer. Check out the busy heart muscle in action!

Learn More About Your Amazing Body!


Updated on July 15, 2022 Reviewed by Betty Choi, MD

Updated on July 15, 2022

Reviewed by Betty Choi, MD