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11 Eye-Opening Facts About the Thyroid

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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.

The thyroid is a small, butterfly-shaped gland that lives just below your larynx. Its two halves, or lobes, which rest against the trachea, weigh less than an ounce. The thyroid is under the control a peanut-shaped gland in the brain called the pituitary gland, which in turn takes its commands from the hypothalamus, a region of the brain that works as the communications center for the pituitary—sending messages in the form of hormones to control the release of thyroid hormones from the pituitary.

Once stimulated, the thyroid gland takes up iodide from the foods we eat and converts it into iodine to make the thyroid hormones thyroxine (T4) and triiodothyronine (T3). These hormones are then released into the bloodstream, where they help your body regulate so many processes it would take several pages to describe them all. Generally, these hormones dictate your metabolism, digestion, fertility, weight loss, aging, and more.

Mental Floss spoke to a few experts to better understand this small but powerful gland. Here are 11 things we learned.

1. YOUR THYROID INFLUENCES EVERY CELL IN YOUR BODY.

Thyroid hormones regulate the metabolic functions of literally every cell in the body by stimulating nearly all tissues in the body to produce proteins and by increasing oxygen available to cells.

2. IT'S ALSO YOUR BODY'S FURNACE.

You can think of your thyroid gland as your body’s furnace, and your pituitary gland as its thermostat, says Michelle Corey, a functional medical practitioner and author of The Thyroid Cure: The Functional Mind-Body Approach to Reversing Your Autoimmune Condition and Reclaiming Your Health! When the furnace (thyroid) gets too cold, the thermostat (pituitary) senses it and produces TSH to stimulate thyroid hormone production, which warms you up. When the levels of thyroid hormones rise and the furnace gets too hot, the pituitary gland then slows the production of TSH, cooling you down.

3. YOUR THYROID AND YOUR LIVER HAVE A TIGHT PARTNERSHIP.

The liver is the major location where T4 is converted into the active T3. If your liver is taxed for any reason, it can’t do the job of converting these hormones, and you won’t have enough of the active thyroid hormone circulating in your body. As a result, you’ll feel sick and tired, even if you’re taking T4 hormone replacement. “If you have been diagnosed with an autoimmune thyroid condition, such as Hashimoto’s disease, supporting your liver is critical to recovery,” Corey says.

4. THYROID DISORDERS CAN BE DIFFICULT TO DIAGNOSE.

Often, symptoms of thyroid disorder may go unnoticed “since they are gradual and non-specific,” says Nilem Patel, an endocrinologist at Los Angeles’s Adventist Health White Memorial Hospital. “Left untreated, thyroid disorder can cause disruption in patients’ lives,” he says. Dysfunction in the thyroid can cause the thyroid to overproduce or underproduce thyroid hormones. If you suspect an issue with your thyroid, request tests beyond just your baseline TSH levels, including T3 and T4 levels as well as thyroid antibodies.

5. ANXIETY AND INSOMNIA CAN BE SIGNS OF AN OVERACTIVE THYROID …

Your wee hour tossing and turning, as well as a racing heart and anxiety, could actually be symptoms of hyperthyroidism, or the overproduction of thyroid hormone. Other symptoms include fatigue, weight loss, palpitations, increased heart rate, and nervousness.

6. … WHILE SUDDEN WEIGHT GAIN AND DEPRESSION MIGHT BE CAUSED BY AN UNDERACTIVE THYROID.

When these symptoms seemingly come out of nowhere, they can be evidence of an underproduction of thyroid hormone. Other common signs of a sluggish thyroid include fatigue, hair loss, constipation, dry skin, irregular menses, cold intolerance, brittle hair, slow heart rate, and general lethargy.

7. IT CAPTURES AN ESSENTIAL ELEMENT.

“The thyroid is the only gland to take up and trap iodine,” says Alan P. Farwell, section chief of endocrinology, diabetes, and nutrition at Boston Medical Center.

Thyroid hormones are also the only iodine-containing hormones. The thyroid gland not only takes up this element from dietary sources but stores a significant amount of iodinated tyrosines (a kind of amino acid) to maintain thyroid hormones in instances of iodine deficiency.

8. IT STORES A POTENTIALLY LETHAL DOSE OF HORMONES.

The gland can store a very large amount of hormone—so much that if the gland released all of its hormone into the bloodstream at once, it could kill you (this is known as thyrotoxicosis), says Linda Anegawa, a Hawaii-based physician with a specialty in obesity medicine. Fortunately thyroid hormone is very tightly regulated by constant, exquisitely sensitive signals traveling between the brain, the gland, the body’s tissues, and the blood concentrations of the hormone at any given moment.

9. THE THYROID PLAYS A CRITICAL ROLE IN PREGNANCY AND FETAL DEVELOPMENT.

To meet the increased metabolic needs of a pregnancy, a mother’s brain stimulates the thyroid gland to produce more hormone. “In the uterus, the fetal thyroid gland begins to function by 18 weeks of gestation. Should the fetus not get enough thyroid hormone from either the mother or from its own gland, severe outcomes can occur including abnormal brain development, abnormal growth of the skeletal system, problems with the placenta, or even miscarriage and increased perinatal mortality risk,” Anegawa says.

10. BALANCING YOUR THYROID MIGHT HELP YOU AVOID CHOLESTEROL-LOWERING DRUGS.

“I sometimes see patients with very elevated cholesterol on cholesterol-lowering medication that doesn’t seem to be working. But then I discover that their thyroid function is off-kilter,” says Anegawa. In these cases, she generally recommends adjusting a patient’s thyroid medicines or beginning treatment for at least six to eight weeks prior to checking the blood cholesterol level. This has helped some of her patients reduce their doses of cholesterol medicines, or stop taking them completely. “[Thyroid hormones] may someday be used as a cholesterol treatment, especially for patients who cannot tolerate statins, the most commonly used drugs,” she says.

11. SYNTHETIC THYROID HORMONE MAY HAVE EXCITING NEW MEDICAL USES.

A specially engineered form of thyroid hormone that only targets heart cells is under research as a treatment for heart failure, Anegawa says. Another form of the hormone, which selectively can enter nerve cells, may someday be a treatment for neurodegenerative disease.

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11 Facts About Fingernails
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Whether there's dirt beneath them or polish atop them, your fingernails serve more than just decorative purposes: They help keep your fingertips safe and have a multitude of special functions that even your doctor might not be aware of. “The nails occupy a unique space within dermatology and medicine in general, particularly because they are such a niche area about which few people have expertise,” Evan Rieder, assistant professor in the Ronald O. Perelman Department of Dermatology at NYU Langone Health, tells Mental Floss.

1. FINGERNAILS HAVE FOUR MAIN PARTS.

Along with skin and hair, nails are part of the body's integumentary system, whose main function is to protect your body from damage and infection. Fingernails have four basic structures: the matrix, the nail plate, the nail bed, and the skin around the nail (including the cuticle).

Fingernail cells grow continuously from a little pocket at the root of the nail bed called the matrix. The pale, crescent-shaped lunula—derived from Latin for "little moon"—on the nail itself is the visible portion of the matrix. If the lunula is injured, the  nail won't grow normally (a scarred lunula can result in a split nail), and changes in the lunula's appearance can also be signs of a systemic disease.

Fingernail cells are made of a protein called keratin (same as your hair). As the keratin cells push out of the matrix, they become hard, flat and compact, eventually forming the hard surface of the nail known as the nail plate. Beneath that is the nail bed, which almost never sees the light of day except when there's an injury or disease.

Surrounding the matrix is the cuticle, the semi-circle of skin that has a tendency to peel away from the nail. The skin just underneath the distal end of the fingernail is called the hyponychium, and if you've ever trimmed your nails too short, you know this skin can be slightly more sensitive than the rest of the fingertip.

2. THEY GROW AT A RATE OF 0.1 MILLIMETERS A DAY ...

That's about 3 to 4 millimeters per month. But they don't always grow at the same speed: Fingernails grow more quickly during the day and in summer (this may be related to exposure to sunlight, which produces more nail-nourishing vitamin D). Nails on your bigger fingers also grow faster, and men's grow faster than women's. The pinky fingernail grows the slowest of all the fingernails. According to the American Academy of Dermatology, if you lose a fingernail due to injury, it can take up to six months to grow back (while a toenail could take as much as a year and a half).

3. ... BUT NOT AFTER YOU'RE DEAD.

You've probably heard that your fingernails keep growing after death. The truth is, they don't, according to the medical journal BMJ. What's actually happening is that the skin around the base of the fingernails retracts because the body is no longer pumping fluids into the tissues, and that creates a kind of optical illusion that makes the nails appear longer.

4. ITS ESTIMATED THAT 20 TO 30 PERCENT OF PEOPLE BITE THEIR NAILS.

Scientists say it's still unclear why, but they suspect nail-biters do it because they're bored, frustrated, concentrating, or because it just feels comforting (and anxiety doesn't seem to play a big role). Perfectionists who don't like to be idle are very likely to have the habit. Biters expose themselves to the dangerous crud that collects underneath the nail: The hyponychium attracts bacteria, including E. coli, and ingesting that through nail-biting can lead to gastrointestinal problems down the line. Biting can also damage teeth and jaws.

5. HUMAN FINGERNAILS ARE BASICALLY FLAT CLAWS.

Our primate ancestors had claws—which, like nails, are made of keratin. As human ancestors began using tools some 2.5 million years ago (or even earlier), evolutionary researchers believe that curved claws became a nuisance. To clutch and strike stone tools, our fingertips may have broadened, causing the claws to evolve into fingernails.

6. THE NAIL ACTUALLY MAKES YOUR FINGERTIP MORE SENSITIVE.

While the fingernail may be tough enough to protect tender flesh, it also has the paradoxical effect of increasing the sensitivity of the finger. It acts as a counterforce when the fingertip touches an object. "The finger is a particularly sensitive area because of very high density of nerve fibers," Rieder says.

7. FINGERNAILS CAN REVEAL LUNG, HEART, AND LIVER DISEASES.

"One of the most interesting facts about fingernails is that they are often a marker for disease within the body," Rieder says. Nail clubbing—an overcurvature of the nail plate and thickening of the skin around the nails—is a particularly significant sign of underlying illness, such as lung or heart disease, liver disease, or inflammatory bowel disease. Two-toned nails—whitish from the cuticle to the nail's midpoint and pink, brown, or reddish in the distal half—can be a sign of kidney and liver disease. Nails that are two-thirds whitish to one-third normal can also be a sign of liver disease. However, little white marks on your nails, known as milk spots (or punctate leukonychia) are just the remnants of any kind of trauma to the nail, from slamming it in a door to chewing on it too fervently.

8. YOU CAN GET A COMMON SKIN DISEASE ON YOUR NAILS.

Psoriasis is "typically thought of as a skin disease, but is actually a skin, joint, and nail disease, and when severe, a marker of cardiovascular risk," Rieder says. Psoriatic fingernails may have orange patches called oil spots, red lines known as splinter hemorrhages, lifting of the edges of the nails, and pits, "which look like a thumb tack was repeatedly and haphazardly pushed into the nails," he says.

Doctors often prescribe topical or injected corticosteroids to treat psoriatic nails, but using lasers is an emerging and potentially more cost-effective technique. Rieder relies on a pulsed dye laser, which uses an organic dye mixed with a solvent as the medium to treat nail psoriasis, "which can be both medically and aesthetically bothersome," he says. This laser is able to penetrate through the hard nail plate with minimal discomfort and "to treat targets of interest, in the case of psoriasis, blood vessels, and hyperactive skin," Rieder says.

9. ANCIENT CULTURES DISPLAYED SOCIAL STATUS WITH NAIL ART.

Painting and other forms of decorating nails have a history of offering social and aesthetic cues through variations in nail color, shape, and length, Rieder says. In fact, he adds, in some cultures ornate and well-decorated fingernails "serve as a proxy for social status."

Five thousand years ago in China, men and women of the Ming Dynasty aristocracy grew their nails long and covered them with golden nail guards or bright home-made polishes. The long nails allegedly announced to the world their social rank and their freedom from performing menial labor.

10. A FORMER BEAUTICIAN HELD THE WORLD RECORD FOR THE LONGEST NAILS.

Lee Redmond of Utah started growing her nails in 1979 and kept at it until she held the world record for "longest fingernails on a pair of hands ever (female)" in 2008. Her right thumbnail was 2 feet, 11 inches and the collective length of all her nails was 28 feet, 4 inches. She also applied nail hardener daily and painted them a reflective gold. Unfortunately, she broke her nails in a 2009 car accident and has no plans to regrow them.

More recently, the man who holds the Guinness record for the "longest fingernails on a single hand—ever" chose to chop them off at Ripley's Believe It Or Not! in New York City in July 2018. Shridhar Chillal of Pune, India started growing the nails of his left hand in 1952, when he was 14 years old. At last count, the total length measured 29 feet, 10.1 inches.

11. THE FIRST NAIL CLIPPERS WERE PATENTED IN 1875.

Today, biters don't have to use their teeth to trim their nails. While the earliest tools for cutting nails were most likely sharp rocks, sand, and knives, the purpose-built nail clipper—though it might be more accurately called a circular nail file—was designed by a Boston, Massachusetts inventor named Valentine Fogerty and patented in 1875. The nail clippers we know today were the design of inventors Eugene Heim and Oelestin Matz, who were granted their patent for a clamp-style fingernail clipper in 1881.

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Thousands of Swedes Are Replacing Their Credit Cards with Microchip Implants
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John MacDougall, AFP/Getty Images

Thousands of people in Sweden have opted to trade in their plastic credit cards for tiny microchips implanted underneath their skin, Lund University digital culture lecturer Moa Petersén writes in Quartz. The chips, which use near-field communication (NFC) technology, stand in place of credit cards, key cards, and rail cards—and future applications of this technology are likely to be developed as it gains popularity.

The chips are typically the size of a grain of rice and are implanted just under the skin between the thumb and forefinger. While they're commonly used in pets, some critics say any human application of the technology starts to cross over into dystopian territory.

So why have they caught on in Sweden? Some suggest that Sweden's strong social welfare programs have made Swedes too trusting of their government—a view Petersén disagrees with.

"The factors behind why roughly 3500 Swedes have had microchips implanted in them are more complex than you might expect," she writes, noting that the country fosters a highly technological society. Skype and Spotify were both founded in Sweden, and its citizens tend to place a lot of faith in the latest technologies. The country also has a thriving biohacking scene that promotes bio-digital experimentation. A video by Dezeen shows passengers on Sweden’s SJ Railways, who have had microchips containing their membership number implanted under their skin, simply holding up their hands for the ticket collector to scan.

This trend isn’t just happening in Sweden. Thousands of Germans have gotten microchip implants in recent years, including one man whose microchip contained a link to his last will and testament. In Australia, a technology festival called Pause Fest attracted media attention for giving VIP guests injectable microchips that would grant them access to all areas of the festival, while also unlocking special digital features and allowing them to exchange business cards with ease.

And in the U.S., a software company in Wisconsin announced last year it would give its employees the option of getting microchip implants that could be used to unlock doors, log into their computers, and even purchase vending machine snacks. As for whether microchip implants will go mainstream in the U.S., only time will tell. 

[h/t Quartz]

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