10 Flexible Facts About the Tongue

The human body is an amazing thing. For each one of us, it’s the most intimate object we know. And yet most of us don’t know enough about it: its features, functions, quirks, and mysteries. Our series The Body explores human anatomy, part by part. Think of it as a mini digital encyclopedia with a dose of wow.

Your tongue is good for a lot more than eating an ice cream cone or a giving a rude gesture during a moment of road rage. Not only does the tongue play a crucial role in your sense of taste, it’s important to breathing, swallowing, speaking, and singing.

Your tongue is actually made of eight interwoven, striated muscles that can move in any direction. It’s thick with glands and fat, and covered in a mucus membrane, which is why it’s always moist. Here, Erich Voigt, otolaryngologist and clinical associate professor at NYU Langone Medical Center, reveals to Mental Floss some underappreciated facts about the tongue.

1. TASTE RECEPTORS ARE CONCENTRATED ON THE TIP OF YOUR TONGUE …

They're also clustered along the sides and at the back; the middle of the tongue is the least receptive area. The tongue is covered with tiny nodes called papillae, which house your taste buds, as well as the serous glands, required for the act of tasting.

2. … AND THE IDEA THAT THE TONGUE HAS FLAVOR ZONES IS A MYTH.

That tongue map with different zones for different flavors that we all grew up learning? It's wrong. All taste buds are capable of detecting the five types of taste (sweet, sour, salty, bitter, and savory), though different receptors are more responsive to different flavors.

3. BLAME YOUR KID'S "SWEET TOOTH" ON HER TONGUE.

If you’ve ever wondered why you used to be able to enjoy a mouthful of sugar and now find candy too sweet, it’s probably because the types of taste buds you have change as you age. Kids' taste buds are more sensitive to sweet tastes than adults' tongues are. “It explains why children really enjoy sweets and candies, as compared to adults who may enjoy more complex flavors and spices,” Voigt says. There are likely evolutionary reasons for this sweet, er, tongue.

4. THE THYROID GLAND DEVELOPS IN THE TONGUE.

When a fetus is developing, says Voigt, the embryonic thyroid gland “starts in the tongue and then descends down the neck as a child forms.” In certain rare cases, the thyroid doesn’t drop, and can be located in the base of the tongue at birth. This is called a lingual thyroid, and requires removal and medication. This condition may not be caught right away—usually doctors don’t notice until symptoms of hyperthyroidism turn up, or a goiter, a swelling of the thyroid, appears.

5. IT'S NOT THE STRONGEST MUSCLE IN THE BODY.

It's a common misconception, says Voigt. But depending on how you measure strength, that title could be more justifiably claimed by the heart, the jaw bone's masseter, or the gluteus maximus in your butt. While the tongue is very strong because “it’s made up of many muscles both intrinsic and extrinsic,” Voigt says, its notability lies in its flexibility. The tongue has unique biomechanics—unlike other muscles, it doesn't surround any supporting bones, and it needs to be able to make three-dimensional changes in shape to handle all the speaking, eating, and swallowing we require of it.

6. THE ABILITY TO DO TONGUE TRICKS ISN'T GENETIC.

Can’t make a fleur de lis with your tongue? Not your mom’s fault. It turns out that the longstanding belief that the ability to roll, flip, and bend your tongue is a genetic trait is not true. John McDonald, an evolutionary biologist at the University of Delaware, recently debunked this myth in an NPR interview. If such an ability were genetic, then identical twins would both be able to do it, which is not the case, as was shown in a 1952 study by geneticist Philip Matlock.

7. IT HAS SOME REAL NERVE.

Actually, it has two, and they're distinctly different, which Voigt says is atypical. “The tongue has very unique nerve innervation. The anterior [forward] two-thirds gets a different nerve from the posterior [back] one third,” he says.

8. YOUR TONGUE CAN LOOK LIKE A MAP…

Geographic tongue is an unusual condition in which a loss of the tiny papillae that normally cover the tongue’s surface creates irregular raised, red patches on the tongue that can resemble continents or islands on a map. Doctors don’t understand the causes of this bizarre condition, though stress, allergies and eating habits may be responsible. Voigt says, in some cases, those patches “might even grow hair.”

9. … AND GET A SEXUALLY TRANSMITTED DISEASE.

The human papillomavirus (HPV) is a sexually transmitted disease that typically afflicts the genitals of humans. It can result in genital warts and is a risk factor for cervical cancer. Unfortunately, says Voigt, “The base of the tongue is one of the increasing forms of cancer due to infection from HPV, which is spread there through oral sex.” Other forms of tongue cancer can result from drinking alcohol, chewing tobacco, and chewing betel nut.

10. STICKING OUT YOUR TONGUE ISN'T ALWAYS RUDE.

In Tibet, sticking out your tongue is a considered a polite greeting between two people when they meet. And among the Maori people of New Zealand, sticking out the tongue is part of a ritual called a haka, where men stick out their tongues in a simulated war dance to intimidate the enemy.

10 Smart Facts About Your Gut

Colorized scanning electron micrograph of E. coli, a common gut bacteria
Colorized scanning electron micrograph of E. coli, a common gut bacteria
National Institute of Allergy and Infectious Diseases, Flickr // CC BY 2.0

Gut feelings get all the press, but your gut may be more of a thinker than you know. Some scientists now consider it a second brain. While it won’t necessarily help you study for an exam or get a promotion, your gut can influence the chemistry of your mood, emotions, immune system, and long-term health. Research even suggests the gut can “learn” new tricks through conditioning. These powerful connections are part an emerging field of science called neurogastroenterology designed to study the gut-brain link. Here are 10 facts you may not know about your gut.

1. THE GUT DOESN'T NEED THE BRAIN'S INPUT. 

You might think of your gut as a rebel against authority. It doesn’t wait for your brain’s impulses to do the important work of digestion, because it doesn’t need to—it acts as its own “brain.” No other organ, not even the all-powerful heart, can pull that off.

2. THERE ARE MORE THAN 100 MILLION BRAIN CELLS IN YOUR GUT.

Your gut’s power to think for itself is no surprise; there are millions of neurons in its lengthy coils (9 meters of intestines, from esophagus to anus). That’s more neurons than are found in the spinal cord or peripheral nervous system.

3. YOUR GUT HAS ITS OWN NERVOUS SYSTEM.

The enteric nervous system—the controlling mechanism of digestion and elimination—is the overlord of your gut, and functions all on its own. Some scientists see it as part of the central nervous system, while others consider it its own entity. It likely evolved to give the gut the go-ahead when the “got to go” impulse strikes, without requiring the brain’s sign-off, particularly when you consider the helplessness of an infant with its brand-new brain.

4. THERE'S AN INFORMATION HIGHWAY FROM YOUR GUT TO YOUR BRAIN.

There’s one big visceral nerve embedded in your gut—the vagus nerve. Research has revealed that up to 90 percent of its fibers carry information from the gut to the brain, rather than the other way around. In other words, the brain interprets gut signals as emotions. So you really should trust your gut.

5. MOST OF YOUR SEROTONIN IS IN YOUR GUT.

Some 95 percent of your body’s serotonin, that marvelous mood molecule that antidepressant drugs like Prozac keep in your body, can be found in the gut. So, it’s no wonder that diet, medications, and antibiotics can wreak havoc on one’s mood.

6. A HEALTHY GUT MAY PROTECT YOUR BONES.

In a study of the serotonin-gut relationship, scientists discovered an unexpected link between the gut and the bones. Inhibiting the gut’s release of serotonin counteracted the bone-density reduction of osteoporosis in mice. This research is going into studies on new osteoporosis-fighting drugs.

7. RESEARCH SHOWS LINKS BETWEEN AUTISM AND HAVING FEWER STRAINS OF GUT BACTERIA. 

In as many as nine out of 10 cases, autistic people have common gut imbalances such as leaky gut syndrome, irritable bowel syndrome, and fewer strains of “good” bacteria. Research on mice is looking at possible treatments of some of the behavioral disorders of autism by balancing microbes in the guts, though many warn that such treatments can’t produce a “cure” for autism.

8. FOOD REALLY DOES AFFECT YOUR MOOD. 

Different foods, when introduced to the gut via feeding tubes, have been shown to change a person's moods without the person’s awareness of what they were "eating." Fat, for instance, increased feelings of happiness and pleasure (no surprise there) because appeared to trigger the release of dopamine—the brain’s natural opiate. Carbohydrate consumption stimulated the release of serotonin, the “feel good” neurotransmitter.

9. YOUR GUT IS YOUR BEST FRIEND IN COLD AND FLU SEASON.

Not only does your gut hold brain cells, it also houses the bulk of your immune cells—70 percent—in the form of gut associated lymphoid tissue, or GALT, which plays a huge part in killing and expelling pathogens. GALT and your gut microbiome—the trillions of bacteria that live, like an immense microbial universe, in your gut—work hard to help you get over what ails you. That’s all the more reason to be careful with the use of antibiotics, which wipe out the good bacteria along with the bad.

10. YOUR GUT CAN BECOME ADDICTED TO OPIATES.

Inside your gut are opiate receptors, which are also found in the brain. The gut is just as susceptible to addiction as the brain and may contribute to the intense difficulty some addicts have trying to kick the habit.

What Causes Hiccups?

iStock/damircudic
iStock/damircudic

The cause of hiccups depends on whom you ask. The ancient Greek physician Galen thought hiccups were violent emotions erupting from the body, while others thought they were a sign of liver inflammation. Today, evidence points to spasms in the diaphragm, the large muscle between the chest and abdomen that aids airflow during breathing. This involuntary contraction can be brought on by a number of things that might irritate the nerves that control the movement of the muscle. A full stomach, heavy boozing, rapid shifts in temperature either inside or outside of the stomach, and certain emotions like shock or excitement are all common culprits.

No matter the cause, the result is the same: The diaphragm spasms and causes us to take a quick breath. The sudden rush of air causes the epiglottis (the flap that protects the space between the vocal cords) to shut and interrupt the breath, which makes the familiar "hic" sound.

WHAT CURES THEM?

The best cure for hiccups also depends on the person you ask. Almost all cures are based on one of two principles: One type works its magic by overwhelming the vagus nerve with another sensation. The vagus nerve is a cranial nerve that innervates the stomach and conveys sensory information about the body's organs to the brain. When distracted by overwhelming information of another sort, it basically tells the brain that something more important has come up and the hiccuping should probably be stopped (vagus nerve stimulation is also used to control seizures in epileptics and treat drug-resistant cases of clinical depression). The other method for curing hiccups is to interfere with the breathing, increasing the amount of carbon dioxide in the blood, and causing the body to focus on getting rid of the of the CO2 and not making hiccups.

Swallowing a spoonful of sugar is probably the most commonly prescribed hiccup cure and falls into the first category. A teaspoon of sugar is usually enough to stimulate the vagus nerve and make the body forget all about the hiccups. Even ardent supporters of the sugar cure disagree if the sugar should be taken dry or washed down with water, though.

If this home remedy doesn't work, and your hiccups are both severe and persistent, you may need to bring out the big guns. For chronic cases like this, doctors sometimes use a cocktail of Reglan (a gastrointestinal stimulant) and Thorazine (an anti-psychotic with sedative properties) to quiet things down. In some cases that resist these drugs, Kemstro, an anti-spasmodic, is also used. Other doctors have used vagus nerve stimulators implanted in the upper chest of patients. The pacemaker-like devices send rhythmic bursts of electricity through the vagus nerve to the brain to keep the hiccup cycle in check.

Many people prefer home remedies to battle their hiccups, which may include holding your breath, gargling ice water, or breathing into a paper bag. While the same people will swear by the treatment they've been using all these years, there's no firm scientific consensus that any of them actually work. But if it helps you, isn't that all that matters?

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

An earlier version of this article appeared in 2012.

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