The human heart beats 60 to 100 times each minute.
A whale, 10 to 30 beats per minute.
A cat, 150 beats per minute.
The heart is mostly muscle. It’s a pump.
The heart pumps about 2,000 gallons of blood every day.
By contrast, it takes about five gallons of paint to redo the interior of 2,000-square-foot home.
The heart moves, of course, as it beats.
The pericardium is key. The word pericardium is from Greek—peri (around) and kardia (heart.)
The pericardium is essentially a sac. It provides a kind of cushion as the heart thumps. The outer layer surrounds the roots of the heart’s major blood vessels. These are known as your “great vessels” and include the aorta, pulmonary artery, pulmonary veins, and superior and inferior vena cava (hollow vein).
The pericardium holds the heart in place. It also protects the heart from infections and provides lubrication to reduce friction between your heart and surrounding tissues.
The movements of the heart are intricate, especially when it comes to the timing of the valves that keep the blood flowing. It’s truly a marvel. There’s a step-by-step breakdown of the flow by Siebert Science here.
And it’s all triggered/jumpstarted by the sinoatrial node, located at the top of the right atrium. An electrical impulse from the node travels through the muscle fibers of the atria and ventricles, causing them to contract.
Our knowledge of the SA Node, as it’s also known, isn’t that old. It wasn’t until 1907 when it all came together, but as with all “discoveries” it was built on previous scientific analysis. There’s an overview of the history here. Much of the 19th Century, it should be noted, was devoted to trying to understand whether the heart’s movement was the result of muscles or nerves.
Okay, we can hear you thinking, that’s all well and good and the heart anatomy is truly fascinating, but it’s February and Valentine’s Day and when did the heart become associated with love?
Well, according to Wikipedia, the first known depiction of a heart as a symbol of romantic love dates to the 1250s but, of course, there is controversy about that. (Spoiler alert: it’s possible the shape was a pear.)
But today the heart is ubiquitous—boxes of chocolate shaped like a heart, advertising campaigns that replace the word ‘love’ with a red heart, Valentine’s Day cards filled with the symbol, and the ever-popular heart emoji, too (though we have no idea how many of the 5 billion emojis sent EVERY SINGLE DAY are hearts). If you’d like a 90-second overview of the history of the heart as a symbol, check this video here.
Want to learn more about heart anatomy? Anatomy in Clay® Learning System is offering a brand new online course taught by Debbi Warren. The 75-minute course covers anatomical structures of the heart, functions of the heart, how to build it in clay, electrocardiograms and rhythms of the human heart, and how to build injuries of the heart in clay. There are several pricing options to meet your particular needs.
In short, we love this course and hope you will, too!
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