9 Fascinating Facts About the Vagus Nerve

The vagus nerve is so named because it “wanders” like a vagabond, sending out sensory fibers from your brainstem to your visceral organs. The vagus nerve, the longest of the cranial nerves, controls your inner nerve center—the parasympathetic nervous system. And it oversees a vast range of crucial functions, communicating motor and sensory impulses to every organ in your body. New research has revealed that it may also be the missing link to treating chronic inflammation, and the beginning of an exciting new field of treatment for serious, incurable diseases. Here are nine facts about this powerful nerve bundle.

1. THE VAGUS NERVE PREVENTS INFLAMMATION.

A certain amount of inflammation after injury or illness is normal. But an overabundance is linked to many diseases and conditions, from sepsis to the autoimmune condition rheumatoid arthritis. The vagus nerve operates a vast network of fibers stationed like spies around all your organs. When it gets a signal for incipient inflammation—the presence of cytokines or a substance called tumor necrosis factor (TNF)—it alerts the brain and draws out anti-inflammatory neurotransmitters that regulate the body’s immune response.

2. IT HELPS YOU MAKE MEMORIES.

A University of Virginia study in rats showed that stimulating their vagus nerves strengthened their memory. The action released the neurotransmitter norepinephrine into the amygdala, which consolidated memories. Related studies were done in humans, suggesting promising treatments for conditions like Alzheimer’s disease.

3. IT HELPS YOU BREATHE.

The neurotransmitter acetylcholine, elicited by the vagus nerve, tells your lungs to breathe. It’s one of the reasons that Botox—often used cosmetically—can be potentially dangerous, because it interrupts your acetylcholine production. You can, however, also stimulate your vagus nerve by doing abdominal breathing or holding your breath for four to eight counts.

4. IT'S INTIMATELY INVOLVED WITH YOUR HEART.

The vagus nerve is responsible for controlling the heart rate via electrical impulses to specialized muscle tissue—the heart’s natural pacemaker—in the right atrium, where acetylcholine release slows the pulse. By measuring the time between your individual heart beats, and then plotting this on a chart over time, doctors can determine your heart rate variability, or HRV. This data can offer clues about the resilience of your heart and vagus nerve.

5. IT INITIATES YOUR BODY'S RELAXATION RESPONSE.

When your ever-vigilant sympathetic nervous system revs up the fight or flight responses—pouring the stress hormone cortisol and adrenaline into your body—the vagus nerve tells your body to chill out by releasing acetylcholine. The vagus nerve’s tendrils extend to many organs, acting like fiber-optic cables that send instructions to release enzymes and proteins like prolactin, vasopressin, and oxytocin, which calm you down. People with a stronger vagus response may be more likely to recover more quickly after stress, injury, or illness.

6. IT TRANSLATES BETWEEN YOUR GUT AND YOUR BRAIN.

Your gut uses the vagus nerve like a walkie-talkie to tell your brain how you’re feeling via electric impulses called “action potentials". Your gut feelings are very real.

7. OVERSTIMULATION OF THE VAGUS NERVE IS THE MOST COMMON CAUSE OF FAINTING.

If you tremble or get queasy at the sight of blood or while getting a flu shot, you’re not weak. You’re experiencing “vagal syncope.” Your body, responding to stress, overstimulates the vagus nerve, causing your blood pressure and heart rate to drop. During extreme syncope, blood flow is restricted to your brain, and you lose consciousness. But most of the time you just have to sit or lie down for the symptoms to subside.

8. ELECTRICAL STIMULATION OF THE VAGUS NERVE REDUCES INFLAMMATION AND MAY INHIBIT IT ALTOGETHER.

Neurosurgeon Kevin Tracey was the first to show that stimulating the vagus nerve can significantly reduce inflammation. Results on rats were so successful, he reproduced the experiment in humans with stunning results. The creation of implants to stimulate the vagus nerve via electronic implants showed a drastic reduction, and even remission, in rheumatoid arthritis—which has no known cure and is often treated with the toxic drugs—hemorrhagic shock, and other equally serious inflammatory syndromes.

9. VAGUS NERVE STIMULATION HAS CREATED A NEW FIELD OF MEDICINE.

Spurred on by the success of vagal nerve stimulation to treat inflammation and epilepsy, a burgeoning field of medical study, known as bioelectronics, may be the future of medicine. Using implants that deliver electric impulses to various body parts, scientists and doctors hope to treat illness with fewer medications and fewer side effects.

12 Facts About the Sense of Taste

iStock/m-imagephotography
iStock/m-imagephotography

A lot more than your tongue is involved in the process of tasting food. Taste is not only one of the most pleasurable of the five senses, but a surprisingly complex sense that science is beginning to understand—and manipulate. Here are 12 fascinating facts about your ability to taste.

1. Everyone has a different number of taste buds.

We all have several thousand taste buds in our mouths, but the number varies from person to person. The average range is between 2000 and 10,000. And taste buds are not limited to your tongue; They can be found in the roof and walls of your mouth, throat, and esophagus. As you age, your taste buds become less sensitive, which experts believe may be why foods that you don’t like as a child become palatable to you as an adult.

2. You taste with your brain.

The moment you bite into a slice of pie, your mouth seems full of flavor. But most of that taste sensation is happening in your brain. More accurately, cranial nerves and taste bud receptors in your mouth send molecules of your food to olfactory nerve endings in the roof of your nose. The molecules bind to these nerve endings, which then signal the olfactory bulb to send smell messages directly to two important cranial nerves, the facial nerve and the glossopharyngeal nerve, which communicate with a part of the brain known as the gustatory cortex.

As taste and nerve messages move further through the brain, they join up with smell messages to give the sensation of flavor, which feels as if it comes from the mouth.

3. You can’t taste well if you can’t smell.

When you smell something through your nostrils, the brain registers these sensations as coming from the nose, while smells perceived through the back of the throat activate parts of the brain associated with signals from the mouth. Since much of taste is odor traveling to olfactory receptors in your brain, it makes sense that you won’t taste much at all if you can’t smell. If you are unable to smell for reasons that include head colds, smoking cigarettes, side effects of medications, or a broken nose, olfactory receptors may either be too damaged, blocked, or inflamed to send their signals on up to your brain.

4. Eating sweet foods helps form a memory of a meal.

Eating sweet foods causes your brain to remember the meal, according to a 2015 study in the journal Hippocampus, and researchers believe it can actually help you control eating behavior. Neurons in the dorsal hippocampus, the part of the brain central to episodic memory, are activated when you eat sweets. Episodic memory is that kind that helps you recall what you experienced at a particular time and place. "We think that episodic memory can be used to control eating behavior," said study co-author Marise Parent, of the Neuroscience Institute at Georgia State. "We make decisions like 'I probably won't eat now. I had a big breakfast.' We make decisions based on our memory of what and when we ate."

5. Scientists can turn tastes on and off by manipulating brain cells.

Dedicated taste receptors in the brain have been found for each of the five basic tastes: sweet, sour, salty, bitter, and umami (savory). In 2015, scientists outlined in the journal Nature how they were able to turn specific tastes on or off in mice, without introducing food, by stimulating and silencing neurons in the brains. For instance, when they stimulated neurons associated with “bitter,” mice made puckering expressions, and could still taste sweet, and vice versa.

6. You can tweak your taste buds.

Most of us have had the experience of drinking perfectly good orange juice after brushing our teeth, only to have it taste more like unsweetened lemon juice. Taste buds, it turns out, are sensitive enough that certain compounds in foods and medicines can alter our ability to perceive one of the five common tastes. The foaming agent sodium lauryl/laureth sulfate in most toothpaste seems to temporarily suppress sweetness receptors. This isn't so unusual. A compound called cynarin in artichokes temporarily blocks your sweet receptors. Then, when you drink water, the cynarin is washed away, making your sweet receptors “wake up” so the water tastes sweet. A compound called miraculin, found in the herb Gymnema sylvestre, toys with your sweet receptors in a similar way.

7. The smell of ham can make your food “taste” saltier.

There’s an entire industry that concocts the tastes of the food you buy at the grocery store. Working with phenomena known as phantom aromas or aroma-taste interactions, scientists found that people associate “ham” with salt. So simply adding a subtle ham-like scent or flavor to a food can make your brain perceive it as saltier than it actually is. The same concept applies to the scent of vanilla, which people perceive as sweet.

8. Your taste buds prefer savory when you fly.

A study by Cornell University food scientists found that loud, noisy environments, such as when you’re traveling on an airplane, compromise your sense of taste. The study found that people traveling on airplanes had suppressed sweet receptors and enhanced umami receptors. The German airline Lufthansa confirmed that on flights, passengers ordered nearly as much tomato juice as beer. The study opens the door to new questions about how taste is influenced by more than our own internal circuitry, including our interactions with our environments.

9. Picky eaters may be “supertasters.”

If you’re a picky eater, you may have a new excuse for your extreme dislike of eggplant or sensitivity to the slightest hint of onion. You might be a supertaster—one of 25 percent of people who have extra papillae in your tongue. That means you have a greater number of taste buds, and thus more specific taste receptors.

10. Some of your taste preferences are genetic.

While genetics may not fully explain your love of the KFC Double Down or lobster ice cream, there may be code written into your DNA that accounts for your preference for sweet foods or your aversion to certain flavors. The first discovery of a genetic underpinning to taste came in 1931, when chemist Arthur Fox was working with powdered PTC (phenylthiocarbamide), and some of the compound blew into the air. One colleague found it to have a bitter taste, while Fox did not perceive that. They conducted an experiment among friends and family and found wide variation in how (and whether) people perceived the flavor of the PTC to be bitter or tasteless. Geneticists later discovered that the perception of PTC flavor (similar to naturally occurring compounds) is based in a single gene, TAS2R38, that codes for a taste receptor on the tongue. In a 2005 study, researchers at the Monell Chemical Senses Center found that the version of this gene also predicted a child's preference for sweet foods.

11. Your genes influence whether you think cilantro tastes like soap.

There may be no flavor more hotly debated or deeply loathed than the herb cilantro (also known as coriander). Entire websites, like IHateCilantro.com, complain about its “soapy” or “perfumy” flavor, while those who like it simply think it gives a nice kick to their salsa. Researchers at the consumer genetics company 23andMe identified two common genetic variants linked to people's “soap” perceptions. A follow-up study in a separate subset of customers confirmed the associations. The most compelling variant can be found within a cluster of olfactory receptor genes, which influence our sense of smell. One of those genes, OR6A2, encodes a receptor that is highly sensitive to aldehyde chemicals, which cilantro contains.

12. Sugar cravings have a biological basis.

Your urge for more hot fudge may have little to do with a lack of self-control. Scientists think that our yearning for sweets is a biological preference that may have been designed to ensure our survival. The liking for sweet tastes in our ancient evolution may have ensured the acceptance of sweet-tasting foods, such as breast milk and vitamin-rich fruits. Moreover, recent research suggests that we crave sweets for their pain-reducing properties.

12 Facts About the Pancreas

iStock.com/ericsphotography
iStock.com/ericsphotography

You could live without your pancreas, but it wouldn’t be easy. For one, you would need to give yourself insulin shots on a daily basis because you would develop diabetes. A helping of enzyme pills would also be needed to help you digest food. It's clear that the 6-inch-long pancreas, located behind your stomach, has crucial functions—and that's why diseases like pancreatic cancer and pancreatitis are often so devastating. Here are a few other important facts to know about the pancreas.

1. Pancreas means “all flesh” in Greek.

Around 300 BCE, a surgeon in ancient Greece named Herophilus became the first person to formally describe the pancreas as a gland. However, the organ didn’t get its name until about 400 years later, when another Greek surgeon and anatomist named Ruphos dubbed it the pankreas, meaning “all flesh”—possibly because of its lack of bone or cartilage. (The plural of pancreas, by the way, is pancreata or pancreases.) Later, in the 16th century, people started referring to a dish of cooked calf or lamb pancreas as “sweetbreads.” That name possibly stems from bræd, the Old English word for “flesh.”

2. The pancreas has a head and a tail.

The pancreas has four main parts: the head, neck, body, and tail. The widest part is the head, which is attached to the first part of the small intestine, known as the duodenum. In cases where a pancreatic tumor is present, the head is usually the part that’s affected. However, according to one study from 2008, people with tumors in the body or tail of the pancreas had lower survival rates than those with cancer in the head of the pancreas.

3. The man who discovered the pancreatic duct may have been murdered for his work.

The pancreatic duct is a tiny tube that runs the length of the pancreas and carries digestive juices to the duodenum. Although the ancient Greeks knew about the pancreas, its function and anatomy weren’t fully understood for centuries. That started to change in 1642, when German anatomist Johann Georg Wirsung discovered the pancreatic duct after performing a dissection on a man who had been hanged for murder. He named it the “duct of Wirsung” after himself, which may have upset some people. Wirsung was murdered the following year, allegedly over a disagreement as to who had actually discovered the duct.

4. It functions as both an endocrine and exocrine gland.

Although food never enters the pancreas, the organ does play a key role in digestion. It produces pancreatic fluid, which gets piped through the pancreatic duct to the duodenum. Once it’s in the digestive tract, the enzymes in the fluid help break down fat, protein, and carbohydrates. By sending a substance through ducts to other parts of the body, it functions as an exocrine gland. At the same time, it also functions as an endocrine gland by secreting two hormones directly into the bloodstream to help control blood sugars. Insulin is released when you have too much sugar, and glucagon is released when you don’t have enough sugar.

5. The pancreas can “taste” sugar.

The pancreas has taste receptor cells that let it sense the presence of sugar. It can “taste” artificial sweeteners, too. However, unlike the taste buds on our tongue, it doesn’t relay these sensations back to the brain. Instead, this sensory information helps the pancreas balance out the hormones and maintain healthy glucose levels in the body.

6. Diabetes is the result of damage to pancreatic cells.

For reasons that remain a scientific mystery, people with type 1 diabetes have immune systems that attack the insulin-producing cells in their pancreas. This prevents the cells from making insulin, and without insulin, other cells can't access the glucose in the bloodstream for energy. Sugar then builds up unhealthily in the bloodstream. People with type 2 diabetes, on the other hand, can still produce some insulin, but it’s not enough. Their cells become resistant to insulin (often as a result of obesity), which causes glucose to accumulate in the bloodstream.

7. The pancreas can digest itself.

Pancreatitis refers to the inflammation of the pancreas, but more alarmingly, what’s actually happening is that the digestive enzymes in the gland are going rogue and “digesting the pancreas itself,” according to Medline Plus. Heavy alcohol consumption is the most common cause of the disease, but other causes may include gallstones, cystic fibrosis, or high levels of fats or calcium in the blood. Most people with acute pancreatitis end up in the hospital, and it often goes away in a couple of days. Chronic pancreatitis can result in more serious complications.

8. Scorpion stings can cause pancreatitis.

The venom of a Brazilian scorpion, Tityus serrulatus, can cause pancreatitis, according to researchers at North Carolina State University. One particular enzyme in the venom attacks certain proteins in the gland, which impairs the pancreatic cells' functions and leads to inflammation. In a separate study of a related species (T. stigmurus), researchers found that “acute pancreatitis due to scorpion is usually transient [and] self-limited ... but it could progress to hemorrhagic pancreatitis and lead to death.”

9. Ruth Bader Ginsburg beat the odds and survived pancreatic cancer.

Ten years after she recovered from colon cancer, Ruth Bader Ginsburg received bad news following a routine check-up in 2009: She had pancreatic cancer. Fortunately, surgeons were able to remove the tumor, and at 85 years old (and counting), Ginsburg is now the oldest Justice on the U.S. Supreme Court. However, most people with pancreatic cancer aren’t so lucky. Although it’s less prevalent than skin, breast, and prostate cancers, it’s one of the deadliest. Just 8 percent of pancreatic cancer patients in the U.S. live longer than five years, according to the American Cancer Society.

James Cleary, an oncologist at the Dana-Farber Cancer Institute in Boston, says it’s very hard to catch in the early stages. “The reason pancreatic cancer can be so difficult to catch is number one, it’s a fast-moving cancer and can grow very rapidly,” he tells Mental Floss. “And number two, it can grow in a spot where you don’t get any symptoms until it’s too late.” In some cases, the cancer may start in the pancreas and spread to the liver or lining of the abdomen without any symptoms showing up.

10. Pancreatic surgery is extremely difficult to pull off.

Sometimes, patients with pancreatic cancer will undergo a complicated surgery called a Whipple procedure, which involves the removal of the head of the pancreas, part of the small intestine, the gallbladder and bile duct, and sometimes part of the stomach, too. However, very few people with pancreatic cancer are candidates for surgery—even if the cancer hasn’t yet spread to neighboring organs. That’s because cancer cells sometimes surround important blood vessels, making it “a tricky area” to operate on, according to Cleary. “The pancreas plays a really important role in digestion, and because of that, it’s very close to several important blood vessels and it’s very close to the stomach and small intestine,” he says.

11. There are genetic components to pancreatic cancer.

More than 90 percent of pancreatic cancers involve a mutation of the KRAS gene, which is also responsible for about half of all human cancers, according to Cleary. However, a drug hasn’t been invented yet to turn this particular gene off. “Finding a way to make a drug successfully target KRAS is one of holy grails of oncology," Cleary says. "It is of such great importance to oncology that a Nobel Prize could be awarded to whoever figures out how to make effective KRAS targeted therapy."

Mutations of DNA repair genes occur in up to 20 percent of pancreatic cancer cases. Some of these mutated genes, like BRCA1 and BRCA2, can run in families. This is why some families have several members who end up suffering from pancreatic cancer. Jimmy Carter, for example, lost his father, brother, and two sisters to pancreatic cancer. His mother had breast cancer that migrated to her pancreas. PARP inhibitors (drugs that block a particular enzyme) have been used to target DNA repair genes in breast and ovarian cancers, and there is now hope that they may also be effective in treating pancreatic cancer.

12. An aggressive form of chemotherapy is helping pancreatic cancer patients live longer.

A chemotherapy regimen called FOLFIRINOX has made significant improvements in the care of pancreatic cancer patients ever since it was introduced in 2010 as a treatment for patients with metastatic disease. Before 2010, “It was very, very rare to see anyone with metastatic cancer living longer than one year,” Cleary says. With FOLFIRNOX, it's not uncommon to see patients with metastatic pancreatic cancer living two years. A huge step forward came in June 2018 when researchers from France found that giving FOLFIRINOX after surgery could increase survival by a median of 20 months longer compared to the standard chemotherapy. Now, researchers are conducting trials to see if FOLFIRINOX can effectively be administered before a patient undergoes surgery. Considering that most patients aren’t eligible for surgery at diagnosis, pre-operative FOLFIRINOX could shrink the pancreatic tumor and increase the number of patients that are able to safely receive surgery.

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