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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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What’s the Difference Between Prison and Jail?
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Many people use the terms jail and prison interchangeably, and while both terms refer to areas where people are held, there's a substantial difference between the two methods of incarceration. Where a person who is accused of a crime is held, and for how long, is a factor in determining the difference between the two—and whether a person is held in a jail or a prison is largely determined by the severity of the crime they have committed.

A jail (or, for our British friends, a gaol) refers to a small, temporary holding facility—run by local governments and supervised by county sheriff departments—that is designed to detain recently arrested people who have committed a minor offense or misdemeanor. A person can also be held in jail for an extended period of time if the sentence for their offense is less than a year. There are currently 3163 local jail facilities in the United States.

A jail is different from the similarly temporary “lockup”—sort of like “pre-jail”—which is located in local police departments and holds offenders unable to post bail, people arrested for public drunkenness who are kept until they are sober, or, most importantly, offenders waiting to be processed into the jail system.

A prison, on the other hand, is usually a large state- or federal-run facility meant to house people convicted of a serious crime or felony, and whose sentences for those crimes surpass 365 days. A prison could also be called a “penitentiary,” among other names.

To be put in a state prison, a person must be convicted of breaking a state law. To be put in a federal prison, a person must be convicted of breaking federal law. Basic amenities in a prison are more extensive than in a jail because, obviously, an inmate is likely to spend more than a year of his or her life confined inside a prison. As of 2012, there were 4575 operating prisons in the U.S.—the most in the world. The country with the second highest number of operating prisons is Russia, which has just 1029 facilities.

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What Do Morticians Do With the Blood They Take Out of Dead Bodies?
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Zoe-Anne Barcellos:

The blood goes down the sink drain, into the sewer system.

I am not a mortician, but I work for a medical examiner/coroner. During an autopsy, most blood is drained from the decedent. This is not on purpose, but a result of gravity. Later a mortician may or may not embalm, depending on the wishes of the family.

Autopsies are done on a table that has a drain at one end; this drain is placed over a sink—a regular sink, with a garbage disposal in it. The blood and bodily fluids just drain down the table, into the sink, and down the drain. This goes into the sewer, like every other sink and toilet, and (usually) goes to a water treatment plant.

You may be thinking that this is biohazardous waste and needs to be treated differently. [If] we can’t put oil, or chemicals (like formalin) down the drains due to regulations, why is blood not treated similarly? I would assume because it is effectively handled by the water treatment plants. If it wasn’t, I am sure the regulations would be changed.

Now any items that are soiled with blood—those cannot be thrown away in the regular trash. Most clothing worn by the decedent is either retained for evidence or released with the decedent to the funeral home—even if they were bloody.

But any gauze, medical tubing, papers, etc. that have blood or bodily fluids on them must be thrown away into a biohazardous trash. These are lined with bright red trash liners, and these are placed in a specially marked box and taped closed. These boxes are stacked up in the garage until they are picked up by a specialty garbage company. I am not sure, but I am pretty sure they are incinerated.

Additionally anything sharp or pointy—like needles, scalpels, etc.—must go into a rigid “sharps” container. When they are 2/3 full we just toss these into one of the biotrash containers.

The biotrash is treated differently, as, if it went to a landfill, then the blood (and therefore the bloodborne pathogens like Hepatitis and HIV) could be exposed to people or animals. Rain could wash it into untreated water systems.

This post originally appeared on Quora. Click here to view.

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