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.

Why Do We Get Shivers Up Our Spines?

iStock.com/martin-dm
iStock.com/martin-dm

Picture this: You're sitting on your couch in the dark alone, watching a scary movie. The killer is walking toward an unsuspecting victim, then suddenly jumps out at her. In that moment, the hairs on your body stand up, and you get a shiver down your spine. When you go for a walk on a crisp morning, the same thing happens. When the music swells during your favorite song, you get the shivers again, this time with the little goosebumps on your arms that appear when you get that sensation.

There's a good reason for shivers and goosebumps: they're your body's response to emotion or stress. We got this from our animal ancestors. When they were cold, the hair on their bodies would stand up—the movement of the arrector pili muscle would cause the skin to contract, raising each hair—to provide an extra layer of insulation. This response is also in play when animals feel threatened: their natural reaction is to try to look bigger than their attacker, so their skin and hair expand to play up that effect. The part of the brain called the hypothalamus is what controls this reaction.

So why do goosebumps—also known as cutis anserina or piloerection—appear, aside from the functional purpose of looking larger or creating insulation? It's because our emotions are also connected with the hypothalamus, so sometimes goosebumps are just our body reacting to our brain's signals of intense emotion.

When we feel things like love, fear, or sadness, the hypothalamus sends a signal to our bodies that produces adrenaline in our blood. The signal triggers the arrector pili muscles to contract, and then we have goosebumps caused by emotion. The sudden adrenaline rush may also cause sweaty palms, tears, increased blood pressure, or shivers.

When we listen to music and get shivers, it is a mixture of subjective emotions toward the music and physiological arousal. If we hear a song we get excited about, or a song that makes us sad, the hypothalamus reacts to the sudden change in emotion and we physically feel the shiver along our spine.

This article was republished in 2019.

10 Facts About the Lungs

iStock/pixelfit
iStock/pixelfit

Every cell in your body needs oxygen in order to function properly. Your lungs are obviously crucial in achieving this goal—once you take air into your lungs, oxygen enters the bloodstream and moves through your body. Each cell makes a trade, exchanging oxygen for carbon dioxide—which your bloodstream then transports back to the lungs. When you exhale, you’re actually expelling carbon dioxide (CO2), nitrogen, and water vapor.

So how does your body make this happen? Bronchial tubes connect your lungs to your throat and mouth. These are lined with tiny little hairs called cilia that move in wave-like patterns, which pushes mucus up your throat. At the base of the bronchial tubes are tiny air sacs that hold the air you breathe in, called alveoli. Your right lung has three balloon-like sections, called lobes, which are full of spongy tissue. Your left lung has only two lobes, to make room for the heart. They sit in a special membrane called the pleura, that separates your lungs from the wall of your chest. Altogether, your lungs are a highly efficient machine—and they do a lot more than you might think.

1. Taking in oxygen is only one of your lungs' most important jobs. 

Yes, you need oxygen to live, but if you didn’t expel the carbon dioxide in your lungs, you would die. Carbon dioxide acts as an acid in the body and is generated by muscle action, Wendie Howland, a nurse with Howland Health Consulting, tells Mental Floss. “Your body operates optimally at a fairly narrow pH range, and when you generate extra CO2 by, say, running up the stairs, you bring your pH into the normal range almost immediately by excreting CO2 by breathing deeply.” So exhaling that more toxic CO2 is as important as taking in oxygen.

2. Think of your lungs as big ol' buckets.

Rather than thinking of your lungs as big balloons, Cascari says, “Think of your lungs as buckets of blood with air bubbles going through them.” In fact, your lungs contain as much blood as the entire rest of your body, which is why your center of gravity is above your waist. They produce blood cells as well. Every time your heart beats, it sends an equal amount of blood to your lungs as it does everywhere else in your body. “It’s this incredible system that can respire—an exchange of gas from the air into the blood and the lungs—without leaking. The fact that that goes on day in day out for our whole life is pretty amazing,” he says.

3. Your lungs are huge.

Your lungs are one of your biggest organs, but you might be surprised to learn that if you spread out the surface area of the alveoli, the sacs where oxygen and blood interface, you could cover an entire tennis court, Schroeder says.

4. Without mucus, your lungs would dry up. 

You may not be a big fan of mucus when it’s clogging your chest or nose during a cold, but it’s a “highly underrated, powerful infection-fighting agent in your body with some pretty cool features," says Ray Casciari, a pulmonologist at St. Joseph Hospital in Orange, California. “It’s actually cleaner than blood,” Casciari reveals. “If you take bacteria and expose it to mucus, the mucus will stop the growth of the bacteria. Whereas blood will actually support the growth of the bacteria.” (In fact, researchers in laboratories often deliberately use blood to grow bacteria.) Your mucus is such an important protective agent that you’d die without it. “If you didn’t have mucus in your lungs, you would dehydrate, losing so much water through evaporation that you would die within minutes,” he says. On the other hand, too much mucus production is dangerous.

5. Whatever you inhale quickly goes from your lungs to your brain. 

In under seven seconds, to be precise. Because of your lungs’ enormous surface area and “its intimate relationship with blood vessels that surround it,” says Scott Schroeder, director of Pediatric Pulmonary Medicine at the Floating Hospital of Tufts Medical Center, an inhalation of smoke or a vaporized medicine can reach the brain very quickly.

6. Coughing isn't always bad for your lungs.

Even when you aren’t sick, a normal person coughs about 10 times per day, says Schroeder—whether due to a sticky piece of food, an allergen you accidentally inhale, or your own mucus generated by exercise.

7. Asthma isn't just one disease affecting lung function.

Asthma, which causes wheezing, coughing, and shortness of breath, is actually a number of different illnesses under one name, Schroeder says. The good news is that deaths due to asthma are very uncommon, and have decreased significantly over the last 20 years, he reports (with one notable exception—African-American men age 18–24). But it doesn’t affect everyone equally. Women are much more likely to develop asthma as adults than men, especially if they are overweight. And people in urban areas are more likely to suffer from asthma than those in rural areas, likely due to increased particulate matter in the air from car exhaust and industrial pollutants.

8. Exercise can make asthma—and your lung function—better.

Asthma is actually improved by cardiovascular exercise. Schroeder says there are no sports that people with asthma cannot participate in, “except scuba diving, but I don’t consider that a sport.”

9. You can get lung cancer even if you've never smoked.

“You can spend your whole life in a very clean environment, never having smoked, and still get lung cancer,” Casciari says. Not all lung cancer is caused by cigarette smoking (though the majority is). Casciari cites occupational exposure, radiation exposure, and potential genetic risk factors, although researchers are still exploring the role genetics play. “Folks tend to think of their lungs very little, and when they do, they think, ‘I don’t smoke, so I’m ok,’ but that’s not completely true.”

10. Breakthroughs in lung cancer treatments has improved survival rates. 

For decades, toxic chemotherapy has been the best medicine for treating lung cancer, but it comes with intense side effects. However, several new breakthroughs have recently improved outcomes for patients, says Casciari. Thoracic CT scans, for example, improve survival by 20 percent by providing earlier diagnosis and treatments. Furthermore, new minimally invasive surgery techniques have made recovery from lung cancer surgery much easier, with people being discharged on the same day of surgery. Finally, immunotherapies that target specific cancer markers and harness the immune system itself to fight cancer cells have improved outcomes—and decreased side effects—for lung cancer patients.

This story was first published in 2017.

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