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How Much Blood Is in the Human Body?

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Blood. The very word can prompt syncope (fainting) in hemophobics, or those affected with an irrational fear of the sight of the stuff. Then again, it might be perfectly rational: Blood carries nutrients in our bodies, supports us with oxygen, and protects against infection. Keeping it inside our veins and arteries is ideal, and losing it would understandably provoke some anxiety.

So how much blood does an average adult carry around? And how much can they afford to lose?

For a helpful visual on the former, try heading to the dairy aisle of the grocery store and picking up a gallon of milk. That’s roughly how much blood you’re harboring at any given moment.

Specifically, it’s more like 1.2 to 1.5 gallons, according to Dr. Daniel Landau, a hematologist and oncologist who spoke with LiveScience in 2016. For some adults, that equates to about eight to 10 percent of their body weight; that total blood volume remains stable from roughly the age of 6 on. Babies carry far less blood—about a cup, or the same as your average cat.

Lose some of that and your body begins to notice the absence. That 1.2 to 1.5 gallons is equivalent to 4.5 to 5.5 liters: Blood donors typically give about one pint, or a half-liter, at a time without any serious effects. But if an injury or other calamity prompts you to lose three to four pints, you’re at a Class 3 hemorrhage and a blood transfusion is in order. More than that and your heart can’t maintain blood pressure. (The reason we turn pale when losing blood is because the body is attempting to use vasoconstriction to divert what’s left to critical organs.)

A 200-pound individual will carry far more blood than a 100-pound person and could conceivably lose more of it without coming closer to death. However, researchers have cautioned that blood volume is not totally related to body weight and can also be influenced by body composition. If a person has more fat than lean tissue, or vice versa, it will affect the vascular system.

Using an online blood volume calculator, it’s possible that André the Giant, who weighed about 525 pounds, toted around 21 liters of blood—or four times the amount a normal person would have, not accounting for varying body fat percentages. That's impressive, but André was not among the largest of mammals, no matter what his promoters may have claimed. Consider instead that a blue whale’s 400-pound heart pumps 220 liters through its massive frame, or roughly 58 gallons.

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Big Questions
What Is the Meaning Behind "420"?
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Whether or not you’re a marijuana enthusiast, you’re probably aware that today is an unofficial holiday for those who are. April 20—4/20—is a day when pot smokers around the world come together to, well, smoke pot. Others use the day to push for legalization, holding marches and rallies.

But why the code 420? There are a lot of theories as to why that particular number was chosen, but most of them are wrong. You may have heard that 420 is police code for possession, or maybe it’s the penal code for marijuana use. Both are false. There is a California Senate Bill 420 that refers to the use of medical marijuana, but the bill was named for the code, not the other way around.

As far as anyone can tell, the phrase started with a bunch of high school students. Back in 1971, a group of kids at San Rafael High School in San Rafael, California, got in the habit of meeting at 4:20 to smoke after school. When they’d see each other in the hallways during the day, their shorthand was “420 Louis,” meaning, “Let’s meet at the Louis Pasteur statue at 4:20 to smoke.”

Somehow, the phrase caught on—and when the Grateful Dead eventually picked it up, "420" spread through the greater community like wildfire. What began as a silly code passed between classes is now a worldwide event for smokers and legalization activists everywhere—not a bad accomplishment for a bunch of high school stoners.

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Why Is a Pineapple Called a Pineapple?
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by James Hunt

Ask an English-speaking person whether they've heard of a pineapple, and you'll probably receive little more than a puzzled look. Surely, every schoolchild has heard of this distinctive tropical fruit—if not in its capacity as produce, then as a dessert ring, or smoothie ingredient, or essential component of a Hawaiian pizza.

But ask an English-speaking person if they've ever heard of the ananas fruit and you'll probably get similarly puzzled looks, but for the opposite reason. The average English speaker has no clue what an ananas is—even though it's the name given to the pineapple in almost every other major global language.

In Arabic, German, French, Dutch, Greek, Hebrew, Hindi, Swedish, Turkish—even in Latin and Esperanto—the pineapple is known as an ananas, give or take local variations in the alphabet and accents. In the languages where it isn't, it's often because the word has been imported from English, such as in the case of the Japanese パイナップル (painappuru) and the Welsh pinafel.

So how is it that English managed to pick the wrong side in this fight so spectacularly? Would not a pineapple, by any other name, taste as weird and tingly?

To figure out where things went wrong for English as a language, we have to go back and look at how Europeans first encountered the fruit in question, which is native to South America. It was first catalogued by Columbus's expedition to Guadeloupe in 1493, and they called it piña de Indes, meaning "pine of the Indians"—not because the plant resembled a pine tree (it doesn't) but because they thought the fruit looked like a pine cone (umm, ... it still doesn't. But you can sort of see it.)

Columbus was on a Spanish mission and, dutifully, the Spanish still use the shortened form piñas to describe the fruit. But almost every other European language (including Portuguese, Columbus's native tongue) decided to stick with the name given to the fruit by the indigenous Tupí people of South America: ananas, which means "excellent fruit."

According to etymological sources, the English word pineapple was first applied to the fruit in 1664, but that didn't end the great pineapple versus ananas debate. Even as late as the 19th century, there are examples of both forms in concurrent use within the English language; for example, in the title of Thomas Baldwin's Short Practical Directions For The Culture Of The Ananas; Or Pine Apple Plant, which was published in 1813.

So given that we knew what both words meant, why didn't English speakers just let go of this illogical and unhelpful linguistic distinction? The ultimate reason may be: We just think our own language is better than everyone else's.

You see, pineapple was already an English word before it was applied to the fruit. First used in 1398, it was originally used to describe what we now call pine cones. Hilariously, the term pine cones wasn't recorded until 1694, suggesting that the application of pineapple to the ananas fruit probably meant that people had to find an alternative to avoid confusion. And while ananas hung around on the periphery of the language for a time, when given a choice between using a local word and a foreign, imported one, the English went with the former so often that the latter essentially died out.

Of course, it's not too late to change our minds. If you want to ask for ananas the next time you order a pizza, give it a try (though we can't say what you'd up with as a result).

Have you got a Big Question you'd like us to answer? If so, let us know by emailing us at bigquestions@mentalfloss.com.

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