The following article is from the book Uncle John’s Bathroom Reader Nature Calls.
(Image credit: Wapcaplet)
It’s only a pump, but if you didn’t have one, you wouldn’t be here.
THE HEART OF THE MATTER
In a cave in Pindal, Spain, there’s a surprisingly well-drawn wall painting of an elephant made some 50,000 years ago. In the chest area is a red mark that some people argue is the creature’s ear, a handprint, or a mistake on the artwork. But others say it’s the animal’s heart.
Of course, ancient hunters would have noticed a dying heart in a fresh kill. Ancient Egyptians knew about hearts (which they removed and stored in jars alongside their wrapped, entombed dead). Early Chinese medical practitioners knew it as part of the circulatory system. And the centuries-old sacred Hindu text, the Atharvaveda, included chants for heart health. The Greeks were also aware of a beating heart in the body, but thought it was the home of the soul. The brain, many of them believed, was what kept us alive. By about the 16th century, humankind had a pretty good idea what the heart looked like and what exactly it did, thanks to increasingly sophisticated scientific methods and public acceptance of dissection for the sake of information.
THE FOUR OF HEARTS
(Image credit: Chippolito)
The human heart can be broken down into four anatomical parts: the left and right ventricles and the left and right atria. As the heart muscle contracts, both atria contract, forcing blood into the ventricles, which then contract to force blood out of the heart. Then, while the heart rests a beat, blood fills the organ again. It might seem as if the right and left sides are redundant, but that’s not so. The right side of the heart sends blood to the lungs for oxygen collection; the left side collects the oxygen-laden blood from the lungs and sends it to the cells and other organs.
IS YOUR HEART IN THE RIGHT PLACE?
It’s a myth that your heart is on the left side of your chest— it’s actually more in the center of your body, slightly more to the left than the right. That “rule” doesn’t apply for all humans, though. Science has found instances in which the heart is in the opposite position, as in the case of “mirror-image twins,” identical twins whose body parts are mirrored, as if they’re facing each other through a mirror. In that rare situation, one twin’s heart is to the left, the other’s is to the right. At any rate, no matter where it lies in your chest, if you’re an adult, your heart is about the size of your two fists together.
THE HARDWORKING HEART
(Image credit: rosmary)
In humans, fetal hearts start beating at about four to five weeks and continue to do so, over and over, about every eight-tenths of a second for your entire life. Your heart beats more often when you exercise, get angry, become excited, are frightened, or are otherwise flooded with heart-speeding adrenaline.
If you’re average, your heart will force about a million barrels of blood through your body in your lifetime, and it will beat almost three billion times. If your heart were to stop for even a few seconds, you’d lose consciousness. If it stopped for six minutes or more, you’d die.
I *HEART* YOU
The Romans were the first to propose that the heart was a person’s emotional center, so it didn’t take much to make the connection between the heart and love. The physical reactions we have when we fall in love —that heady rush, the flip-flop in the midsection, the increase in pulse— probably led to that belief. The ancients also thought that there was a vein that ran from the fourth finger of the left hand directly to the heart (there isn’t), which is why we wear wedding rings on the left “ring finger.”
(NOT) COMPLETELY HEARTLESS
Like humans, most other creatures need hearts to stay alive— the exceptions are jellyfish and coral, which don’t have hearts. But that doesn’t mean that all other hearts work like ours do:
• Instead of circulating oxygen-rich blood back to the lungs, a fish’s heart sends the blood to its gills.
• Frogs have three-chambered hearts: two atria and just one ventricle.
• Insects have hearts (of sorts), but their circulatory system is open. This means that bug blood (called hemolymph) flows throughout the insect’s body— not in arteries and capillaries like ours— propelled by a vessel in its abdomen that functions as a heart.
• The blue whale is the largest creature on earth, so it stands to reason that the whale’s heart is the largest, too. A blue whale’s heart can weigh 1,300 pounds… about half the size of the average compact car.
• A hovering hummingbird’s heart flutters at 1,200 beats a minute or more.
• The giraffe has the highest blood pressure in the animal world because its heart must pump blood with extra force to overcome the gravity associated with a head so high. That doesn’t mean the giraffe is a big-hearted fellow, though— its heart is as big as any animal its size. Instead, the walls of a giraffe’s heart are thicker and more powerful. And to accommodate all that extra pressure, the giraffe’s blood vessels also thicken as the animal (and its neck) grows and ages.
• During hibernation, a bear’s heart rate drops to about 22 percent of the number of beats it needs when it’s active— about 19 beats per minute in hibernation versus the normal 84 beats per minute while it’s doing things like raiding your campsite looking for marshmallows.
• The average pig heart is close in size and output to the average human heart, which is why researchers are looking for ways to genetically modify entire pig hearts for use in human chests. At the moment, though, only pig heart valves— stripped of their genetic material to avoid tissue rejection— are used in human heart surgery.
• The first successful human heart transplant was performed in 1967; the patient lived less than three weeks. Today, the first-year survival rate for cardiac transplant patients is 90 percent.
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The article above is reprinted with permission from Uncle John’s Bathroom Reader Nature Calls. From hornywinks to Dracula orchids, from alluvium to zymogen, Uncle John is embarking on a back–country safari to track down the wackiest, weirdest, silliest, and most amazing stories about the natural world.
Since 1988, the Bathroom Reader Institute had published a series of popular books containing irresistible bits of trivia and obscure yet fascinating facts. If you like Neatorama, you'll love the Bathroom Reader Institute's books - go ahead and check 'em out!