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Why Do Our Ears Pop When We Ride In Airplanes?

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You’re sitting on a plane destined for a far off place, sandwiched between two people, and you're doing your best to sit back and get comfortable. But as the plane takes off and makes its rapid ascent toward cruising altitude, a baby begins to cry, the people around you wince, and finally, it hits you—a buildup of pressure, tightening your ears and sinuses, that compresses your head like a vice that won’t let go. The plane continues upward until it stabilizes thousands of feet above the ground and then—POP!—your head feels fine.

Whether you’re in an airplane soaring through the sky, on an elevator heading to the top floors of New York’s tallest skyscraper, or making a deep dive underwater, your ears will most likely pop. The explanation for why this occurs is simple: It’s pressure. But what, exactly, is happening inside your ears?

Under Pressure

When a plane ascends, the air pressure in the cabin lowers at a rapid rate. This sudden change causes an irregularity with the pressure in the inner ear. At such high altitudes, the pressure pushes outward on the eardrum—the thin membrane between the external and middle ear that transmits sound—and causes the tension you feel in your head. (The pressure also reduces your ability to hear.)

One way to release this pressure is through the Eustachian tube, a 1.4-inch long cavity in the middle ear that connects the ears to the nose and throat. Yawning, swallowing, or even chewing gum opens the muscles of the Eustachian tube, causing air to fill the space and equalize that sometimes debilitating pressure caused by rapidly changing altitude. During that equalization, the air forcing into the tube makes that pesky popping or crackling sound, alleviating some of the discomfort the fluctuation caused.

Fancy Maneuver

When yawning or swallowing doesn’t do the trick, people use what is known as the “Valsalva Maneuver.” Named after Antonio Maria Valsalva, a 17th century Italian physician whose scientific specialty was the ear, the maneuver consists of closing the mouth, pinching the nose, and exhaling as if to blow up a balloon. It isn’t recommended, however, as it may cause barotrauma—damage to bodily tissue caused by a pressure difference inside and outside the body—or further auditory damage from the violent pressure equalization pushing outward.

After you’ve heard that pop, the pressure should be equalized, and the pain gone. You can watch some in-flight entertainment, or chow down on the packet of peanuts the flight attendants give you—at least until the descent, when, thanks to the rapidly increasing pressure in the cabin, you might have to go through the discomfort, and popping, all over again.

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science
The T. Rex Fossil That Caused a Scientific Controversy
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In the early 2000s, a team of paleontologists inadvertently set the stage for a years-long scientific saga after they excavated a well-preserved partial Tyrannosaurus rex skeleton from Montana's Hell Creek formation. While transporting the bones, the scientists were forced to break a femur. Pieces from inside the thigh bone fell out, and these fragments were sent to Mary Schweitzer, a paleontologist at North Carolina State University, for dissection and analysis.

Under a microscope, Schweitzer thought she could make out what appeared to be cells and tiny blood vessels inside the pieces, similar to those commonly discovered inside fresh bone. Further analysis revealed what appeared to be animal proteins, which sent Schweitzer reeling. Could she have just discovered soft tissue inside dinosaur leg bone many millions of years old, found in ancient sediments laid down during the Cretaceous period? Or was the soft stuff simply a substance known as biofilm, which would have been formed by microbes after the bone had already fossilized?

Following a seemingly endless series of debates, studies, and papers, Schweitzer's hunch was proven correct. That said, this contentious conclusion wasn't made overnight. To hear the whole saga—and learn what it means for science—watch the recent episode of Stated Clearly below, which was first spotted by website Earth Archives.

[h/t Earth Archives]

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Essential Science
What Is Antibiotic Resistance?
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The news is full of terms like "superbug," "post-antibiotic era," and an alphabet soup of abbreviations including NDM-1, MCR-1 (both antibiotic resistance genes), MRSA (a type of antibiotic-resistant bacteria), and others. These all refer to various aspects of antibiotic resistance—the ability of bacteria to out-maneuver the drugs which are supposed to kill them and stop an infection.

Now, there is concern that we could move back into a situation like that which existed in the early 20th century—a post-antibiotic era. Mental Floss spoke to Meghan Davis, a veterinarian and assistant professor of epidemiology at Johns Hopkins University, about some of the potential outcomes of losing antibiotics. "We have generations of recorded history that identify the risks to human society from infectious diseases that we are unable to treat or prevent," Davis warns.

WHY IS ANTIBIOTIC RESISTANCE DANGEROUS?

If an individual becomes ill due to a bacterial infection, they typically see their physician for treatment. But in the years before antibiotics were discovered, people frequently died from scenarios we find difficult to fathom, including mere cuts or scratches that led to untreatable infections. Ear infections or urinary tract infections could lead to sepsis (bacteria in the blood). Arms or legs were surgically removed before an infected wound could lead to death.

When antibiotics were discovered, it's no surprise they were referred to as a "magic bullet" (or Zauberkugel in German, as conceived by medical pioneer Paul Ehrlich [PDF]). The drugs could wipe out an infection but not harm the host. They allowed people to recover from even the most serious of infections, and heralded a new era in medicine where people no longer feared bacteria.

Davis says the existence of antibiotics themselves has changed how we use medicine. Many medical procedures now rely on antibiotics to treat infections that may result from the intervention. "What is different about a post-antibiotic modern world is that we have established new patterns of behavior and medical norms that rely on the success of antimicrobial treatments," she says. "Imagine transplant or other major surgeries without the ability to control opportunistic infections with antibiotics. Loss of antibiotics would challenge many of our medical innovations."

WHERE DOES ANTIBIOTIC RESISTANCE COME FROM?

One reason antibiotic resistance is difficult to control is that our antibiotics are derivatives of natural products. Our first antibiotic, penicillin, came from a common mold. Fungi, bacteria, parasites, and viruses all produce products to protect themselves as they battle each other in their microbial environments. We've taken advantage of the fruits of millions of years' worth of these invisible wars to harness antibiotics for our use. (This is also why we can find antibiotic resistance genes even in ancient bacteria that have never seen modern antibiotic drugs—because we've exploited the chemicals they use to protect themselves).

These microbes have evolved ways to evade their enemies—antibiotic resistance genes. Sometimes the products of these genes will render the antibiotic useless by chopping it into pieces or pumping it out of the bacterial cell. Importantly, these resistance genes can be swapped among different bacterial species like playing cards. Sometimes the genes will be useless because the bacteria aren't being exposed to a particular drug, but sometimes they'll be dealt an ace and survive while others die from antibiotic exposure.

And many of these resistance genes are already out there in the bacterial populations. Imagine just one in a million bacterial cells that are growing in a human gut have a resistance gene already in their DNA. When a person takes a dose of antibiotics, all the susceptible bacteria will die off—but that one-in-a-million bacterium that can withstand the antibiotic suddenly has a lot of room to replicate, and the population of bacteria carrying that resistance gene will dramatically increase.

If the person then transfers those resistant gut bacteria to others, resistance can spread as well. This is why it's important to keep control over antibiotic use in all populations—because someone else's use of the drugs can potentially make your own bacteria resistant to antibiotics. This is also why hand washing is important: You can unknowingly pick up new bacteria all the time from other people, animals, or surfaces. Washing your hands will send most of these passenger bacteria down the sink drain, instead of allowing them to live on your body.

WHAT CAN YOU DO ABOUT IT?

Most importantly, never ask for antibiotics from your doctor; if you have a bacterial infection that can be treated by antibiotics, your doctor will prescribe them. Many illnesses are due to viruses (such as the common cold), but antibiotics only work against bacteria. It is useless to take antibiotics for a virus, and doing so will only breed resistance in the other bacteria living in your body, which can predispose you or others in your household and community to developing an antibiotic-resistant infection. Remember, those resistant bacteria can linger in your body—in your gut, on your skin, in your mouth and elsewhere, and can swap resistance genes from the mostly harmless bacteria you live with to the nasty pathogens you may encounter, further spreading resistance in the population.

Antibiotics are also used in animals, including livestock. Purchasing meat that is labeled "raised without antibiotics" will reduce your chance of acquiring antibiotic-resistant bacteria that are generated on the farm and can be spread via meat products.

Davis notes clients often requested antibiotics for their pets as well, even when it was an issue that did not require them. She explained to them why antibiotics were not necessary. She counsels, "Individuals can partner with their physician and veterinarian to promote good antimicrobial stewardship. Use of antibiotics carries risks, and these risks are related both to side effects and to promotion of resistance. Therefore, decisions to use antibiotics should be treated with caution and deliberation."

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