12 Facts About the Liver

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You may not think much of your liver, hidden as it is deep inside your body, but your liver runs a whole lot of functions on your behalf to keep you healthy. Not only is it your largest internal organ, it is in charge of hundreds of different functions ranging from fighting infection, to manufacturing proteins and hormones, and helping clot your blood.

This reddish brown organ has two lobes, on the right and left, and it hangs out just on top of the gallbladder and next to parts of the pancreas and intestines. Your liver and these neighboring organs work as a team to digest and absorb your food. Its main job is to filter the blood that comes from the digestive tract, before it hits the rest of your body. The liver also detoxifies chemicals and metabolizes drugs. As it does so, the liver secretes bile that ends up back in the intestines. The liver also makes proteins important for blood plasma and other functions. With some expert support, here are 12 facts about this underappreciated, hardworking organ.

1. IT HAS A LOT OF JOBS.

The liver is a very complicated organ with a role in nearly every bodily function, according to Nancy Reau, MD, the section chief of hepatology and associate director of organ transplantation at Rush University. Some of its jobs include making and storing energy; producing proteins vital for body function; processing drugs—prescriptions, OTCs, and “drugs of abuse”; and playing a vital role in immune function. “Although it’s hard to quantify all of the liver’s many roles, it is easy to see how sick a person becomes when the liver stops functioning,” says Reau, who is also co-chair of the American Liver Foundation’s medical advisory committee.

2. IT'S THE SECOND BIGGEST ORGAN NEXT TO SKIN.

Your liver weighs about the same as a small Chihuahua, often as much as three pounds [PDF], and is about the size of a football. It's located just beneath your rib cage on the right side of your body. If you could feel it, it would be rubbery to the touch.

3. IT HAS A DUAL IDENTITY.

Organs usually have a job specific to one region of the body. Glands are specialized types of organs that remove substances from the blood, alter or process them, then release them to other parts of the body or eliminate them. In that respect, the liver, which filters your body’s toxins (such as drugs and alcohol) and pushes them out of your body, is also a gland.

4. IT'S A BLOODY ORGAN.

At its fullest, the liver holds approximately 10 percent of the blood in your body, and pumps nearly 1.5 liters through itself per minute.

5. THE FIRST LIVER TRANSPLANT WAS NOT A GREAT SUCCESS.

Back in 1963, when Dr. Thomas E. Starzl performed the first human liver transplant at the University of Colorado Medical School, success was limited due to the wrong kinds of immunosuppressive drugs, with no patient living more than a few weeks. However, only four years later, the expansion of available immunosuppressive drugs made the first successful liver transplant possible.

6. IT'S THE ONLY ORGAN THAT CAN COMPLETELY REGENERATE.

Like Wolverine, the liver has the incredible ability to completely regrow, and it only needs as little as 25 percent of the original tissue to do so. “When a person donates more than half of their liver to someone who needs a transplant, the liver returns to its original size in nearly two weeks,” Reau tells Mental Floss. According to a 2009 study in the Journal of Cell Physiology, evolutionary safeguards are responsible for this regenerative effect due to the numerous functions performed by the liver. “This process allows liver to recover lost mass without jeopardizing viability of the entire organism,” the authors write.

7. GOOD THING, BECAUSE YOUR BRAIN DEPENDS ON A HEALTHY LIVER.

The liver is a major regulator of plasma glucose and ammonia levels. If these get out of control they can contribute to a condition known as hepatic encephalopathy, and eventually coma. In other words, if you want your brain to function, you need a working liver.

8. LIVER CONDITIONS MAY BE SYMPTOMLESS.

Liver conditions are among those that pose a quandary for diagnosis. Because many liver conditions from hepatitis to cirrhosis may have no symptoms in the early stages. “You can even have a serious liver injury when your liver tests are all normal,” says Reau.

9. BEWARE YOUR NATURAL SUPPLEMENTS, TOO.

You may think if an herb or supplement has the word natural on the bottle that it’s safe. However, Reau cautions, “Herbs and all-natural therapy [are] processed by the liver in the same way that FDA-approved medications are processed.” It’s best to talk with your doctor if you’re uncertain. Although liver injury is uncommon for both prescribed and complementary therapies, being “all natural” does not eliminate all risk.

10. YOUR LIVER IS CONCERNED ABOUT YOUR WEIGHT …

Your body needs about one gram (.03 ounces) of liver for every kilogram (35 ounces) of your body weight in order to effectively do its job, Dr. Neil Mukherjee, a liver surgeon and fellow at Florida Hospital's Southeastern Center for Digestive Disorders & Pancreatic Cancer, tells Mental Floss.

11. … AND IT RAISES YOUR BILE.

The liver is a busy brew factory of bile, that yellow, green or brownish fluid you only ever see when you’re greeting the toilet with the stomach flu or a hangover. It produces about 700 to 1000 ml of the stuff every day. The bile gathers in little ducts and then moves on to the main bile duct, where it’s carried to the duodenum of the small intestine, either directly or via the gallbladder. While it may sound gross, bile is key to your body's ability to break down and absorb fats.

12. NO MATTER SHAPE OR SIZE, ALL VERTEBRATES HAVE ONE.

Every vertebrate—that is, any living being that has a spinal cord—has a liver, a necessary part of survival. And, these livers all have a similar structure, performing the same essential tasks in all these bodies.

26 Amazing Facts About the Human Body

Mental Floss via YouTube
Mental Floss via YouTube

At some point in your life, you've probably wondered: What is belly button lint, anyway? The answer, according to Mental Floss editor-in-chief Erin McCarthy, is that it's "fibers that rub off of clothing over time." And hairy people are more prone to getting it for a very specific (and kind of gross-sounding) reason. A group of scientists who formed the Belly Button Biodiversity Project in 2011 have also discovered that there's a whole lot of bacteria going on in there.

In this week's all-new edition of The List Show, Erin is sharing 26 amazing facts about the human body, from your philtrum (the dent under your nose) to your feet. You can watch the full episode below.

For more episodes like this one, be sure to subscribe here.

8 Surprising Facts About Your Nose

iStock/AntonioGuillem
iStock/AntonioGuillem

Your nose is more than just a bump on your face—it’s an important part of the respiratory system and affects many other senses, including your taste and hearing. For being something that’s so central to our daily interactions with the world, there’s still a surprising amount to discover about the nose. Here's a bit of what we do know.

1. Your nose can detect billions of different odors.

Although the human nose is weak compared to canine sniffers, our noses can detect 1 trillion smells. Strangely, scientists still aren’t sure exactly how we smell. For decades, researchers thought the olfactory system worked through receptor binding, meaning molecules of different shapes and sizes bonded to specific parts of the nose like puzzle pieces, triggering smell recognition in the brain. But recently, biophysicist Luca Turin has proposed the nose detects smell through quantum vibrations. Turin suggests the frequency at which different molecules vibrate helps the nose identify them as different scents. The theory could explain why molecules of the same shape smell quite differently. Intriguing as it is, this new theory hasn’t been tested enough to be universally accepted.

2. Our big brains might have caused our noses to protrude.

As anyone who’s been to a zoo probably knows, great apes (the closest human ancestors) have flat nasal openings—and researchers found that type of nose is far more effective at inhaling air than the human version. So what’s up with ours? Scientists think the shape might be a by-product of our big brain. The growing cerebellum forced human faces to become smaller, which probably affected the nose as well.

3. Women's noses are more sensitive than men's.

In the battle of the sexes, women’s noses come out on top. When tested for odor detection and identification, women score consistently higher than men. This might have something to do with the size of their olfactory bulb, a structure in the brain that helps humans identify smells. One study found that women have, on average, 43 percent more cells in their olfactory bulb than men do—meaning they can smell more smells.

4. Holding your nose really does help you swallow something distasteful.

Think you like chocolate just because it tastes good? Think again. Smell is responsible for 75 to 95 percent of flavor, which explains why plugging your nose helps you swallow something unappetizing. More recently, chefs and neurologists have teamed up to create meals for cancer patients and others with a diminished sense of smell, such as the elderly. Cooking meals tailored to the smell-less could help stave off depression and improve the appetite without relying on sugar and salt.

5. Surgeons can regrow damaged noses.

When people have cancer or are in an accident, the nose can become infected or even be completely destroyed. But fear not. Plastic surgeons have a way to regrow your nose—on your forehead. Using cartilage from the ribs and tissue expanders that allow the skin to stretch and grow, a new nose can be formed to replace the old one. And while a nose growing out of your forehead looks odd, it's actually one of the best places for a new nose to grow. The forehead's blood vessels can be harnessed to help grow the tissue, and removing the new nose only leaves a small scar [PDF]. Doctors have performed the procedure in the U.S., China, and India.

6. Your nose can sense more than smells.

The nose doesn’t just translate odors in the nasal passage—the tip is also full of nerves that detect pain and temperature. This helps us “smell” non-odor smells. Even people who can no longer smell things with their olfactory system can detect substances like menthol, the minty compound that makes your skin tingle. (Unfortunately, they can’t detect pure scents like vanilla.)

7. About 20,000 liters of air pass through the nose every day.

The average adult breathes around 20,000 liters of air every day, which keeps the nose quite busy. As the first line of defense for the lungs, the nose filters out small particles like pollen and dust. It also adds moisture to the air and warms it so the lungs are saved from any irritation.

8. Anosmia is just one of several smell disorders affecting the nose.

There are plenty of things that can go wrong in your nose. Allergic rhinitis, sinus infections, and broken noses are just a few. But perhaps less well known are disorders that affect the nose’s ability to smell. Anosmia is the complete inability to detect odors and can be caused by illness, aging, radiation, chemical exposure, or even genetics. Equally bizarre are parosmia and phantosmia: The former changes your perception of smells, and the latter creates the perception of smells that don’t exist. Luckily, only 1 or 2 percent of North Americans suffer from any smell disorders.

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