The human body

Bathtubs of snot? The "gross but true" guide to human anatomy

Image: Tima Miroshnichenko

From the tiny, unseen creatures residing on your eyelashes to the incredible volume of mucus your nose produces annually, the inner workings of our anatomy are packed with crazy facts that sound like science fiction. Prepare to have your mind blown as we discover 10 of the most astounding, hard-to-believe truths about our very own body. Get ready to never again look at your saliva, bones, or even your earwax in the same way!

Image: César Couto

Did you know that about 50% of people have tiny creatures living on their eyelashes? These eyelash mites are about a third of a millimetre long. They can sometimes cause allergic reactions, but most people never find out they’ve got them. We bet you're calling your ophthalmologist for a consult right now!

Image: Franco Antonio Giovanella

Earwax is produced by your body to protect the lining of your ear canal by trapping dirt and repelling water. But what will probably baffle you is that by the time it reaches the outer ear, the wax has been inside your ear for about a month. No wonder it tastes so disgusting!

Image: Andrea Piacquadio

You usually only notice snot when you’re making too much of it, that is, when you are sick. But can you guess how much mucus an average person produces in a year? The answer will shock you: about 100 gallons, enough to fill two bathtubs! While the sticky goo is rather unpleasant, you wouldn’t want to go without it. Mucus creates a layer of protection between you and the outside world, so thank God it’s there.

Image: FUHMariaM

And what about your saliva? How many bathtubs do you think you can fill with your year's supply? Saliva helps break down and swallow food, fights bacteria, and neutralizes acid, among many benefits. So, if it is that good for you, it’s no surprise your mouth produces tons of it. In fact, it makes between 250 and 730 quarts a year, equivalent to filling a small swimming pool over a lifetime.

Image: BUDDHI Kumar SHRESTHA

That pink squidgy blob inside your head is stuffed with facts, memories, and dreams. Your brain is constantly crackling with tiny pulses of electricity, performing ten quadrillion calculations per second. They’re brilliantly complicated machines that scientists are only just beginning to understand. One thing is for sure: an average person has 1460 dreams in a year, about four dreams every night, or to put it another way, around the same as the number of miles from Denver to Nashville.

Image: camilo jimenez

Clever as your brain is, it wouldn’t be able to do much without the network of nerves that link it to the rest of your body. Nerves bring information from your senses to your brain and deliver orders from your brain to the other organs. As you can imagine, if we were to measure that amazing network, we would end up with a lot. In fact, every person has a whopping 44 miles of nerves running through their skin. Can you imagine?

Image: Ximena Mora

The outer layer of your skin is called the epidermis and consists of dead cells that provide protection from dirt and germs. What you probably didn’t know is that your body is constantly losing and replacing these cells. Also, your dead skin cells sometimes absorb water and swell. This is the reason the ends of your fingers go wrinkly in the bath. But don’t worry, the entire surface of your skin is replaced every month.

Want to play some more? How much do you think the average adult’s skin weighs? Just under 7 pounds, or as we like to say, the same as three pineapples!

Image: Ashton Bingham

Human hair feels soft, but it’s one of the strongest fibres on the planet. The number of hairs on your head ranges from around 9,000 to 140,000, depending on what sort of hair you have.

Everyone loses about 50 to 100 hairs every day, but this process can speed up in men as they get older. Hair generally grows about half an inch a month, or 6 inches a year. Yet, if you don’t cut it regularly, it will most likely stop growing when it’s about 5 feet long.

Image: cottonbro studio

This fact is not for skeptics: the average adult’s skeleton weighs the same as one car tyre. In fact, our skeleton only makes up about 15 per cent of our overall body weight. So, next time someone tells you that big bones is the reason for them being overweight, be suspicious.

Another fun fact? Your collarbone is the last of your bones to stop growing when you become an adult. Called the clavicle, it doesn’t stop growing until you’re about twenty-five.

Image: The Lazy Artist Gallery

Human muscles, on the other hand, make up about 40% of your body weight, and there are more than 600 of them. Yet, you use just 200 when you take a step, and almost all of them when you throw a ball.

The biggest muscle in your body is the _gluteus maximus_—a.k.a your bum. The smallest is in your ear, the stapedius, just about forty thousandths of an inch. The jaw muscle is the strongest by force, and the eye muscles are the busiest—10,000 movements an hour when reading! Our favorite muscle, though? The heart, of course!

Decoding

Being a "treasured guest" is not a compliment. This is the hidden meaning

Have you ever heard "Code Adam" while shopping for groceries at Walmart? Or maybe you’ve heard how "Dr. Firestone" was being paged during a routine hospital visit. They sound like harmless announcements. But behind these ordinary words are secret codes staff use to signal emergencies without causing panic. From hospitals and supermarkets to airports and Disney Parks, these phrases quietly warn employees that something is happening. You hope you never hear them, but if you do, it helps to know exactly what they mean.

We all love getting special attention at airports or hotel desks, but if you hear the clerk call you a "treasured guest," don’t feel so flattered. You may not be as VIP as one could think.

In the hospitality industry, "treasured guest" has become a humorous bit of industry folklore to describe someone causing trouble. Maybe a customer yelling at staff over expired coupons, demanding impossible accommodations, or throwing a full-blown tantrum at the front desk. Whatever it is, the phrase has become the staff’s secret way to warn co-workers without escalating the situation in front of the customers. Most guests don’t realize the meaning, but once you know it, you may start hearing it more often. We just hope it’s not about you.

Imagine you’re pushing a shopping cart through Walmart when suddenly the overhead speaker announces, "Code Adam." You can easily assume it’s some kind of employee meeting or cleanup request. But when you see them start locking the exits and moving around, you know something’s wrong.

This code was created in 1994 by Walmart in collaboration with the National Center for Missing & Exploited Children (NCMEC), in memory of the tragic case of 6-year-old Adam Walsh. Adam was abducted from a Sears department store in 1981 while shopping with his mother. His father, John Walsh, later became famous for hosting the TV program America’s Most Wanted and advocating for missing children. Even if Adam’s story ended in tragedy, Walmart created the emergency system in Adam’s memory, and other retailers soon adopted it nationwide, intending to have a quick response to missing or abducted children.

You’re sitting in a hospital waiting room during a routine check-up when you suddenly hear "Code Blue, Room 214." Most people immediately know it sounds serious, even if they are not entirely sure why.

The phrase "Code Blue" is used at hospitals to draw the necessary staff and equipment to perform a resuscitation. It was created in the early 1960s at Beathany Medical Center by Dr. Hughes Day. Before then, hospital resuscitations were often chaotic and poorly coordinated. In 1961, Dr. Day received a grant to build one of America’s first cardiac care centers, and he developed both the Code Blue alert system and the modern crash cart to improve survival rates during cardiac emergencies. Today, the system is used in hospitals across the country, sometimes with specialized versions like "Code Blue Pediatric" or "Code Blue Neonate."

Imagine visiting a loved one in the hospital when the intercom calmly announces, "Paging Dr. Firectone to the third floor." Your head surely goes, "Dr. Firestone’s probably having a busy day up there." He is, but it’s not what you think.

The phrase is actually a discreet fire alert used to warn staff about smoke, flames, or overheating equipment without frightening patients and visitors. Hospitals adopted these coded announcements after realizing that openly yelling "fire" over loudspeakers could create panic, especially among patients who aren’t able to move quickly. "Code Red" is an alternative used by many health centers today, but it also hints at the situation while keeping hallways calm.

You’re standing at a checkout counter when the cashier picks up the phone and quietly says, "I need a Code 10 authorization." If you think that’s just another way to get a supervisor’s approval or technical issue, think again. In reality, the cashier may suspect the credit card is stolen or fraudulent.

Code 10 was developed through a cooperative effort between major credit card companies like Visa and Mastercard, along with international standard organizations. As credit cards became more common in the 1960s and 1970s, stores needed a discreet way to alert banks about suspicious activity without directly accusing customers and potentially putting employees at danger. When a cashier requests a Code 10, the bank’s operator begins asking yes-or-no questions to assess the situation and guide the employee on what to do next.

You’ve probably experienced those long airport security lines. The wait is usually uneventful. But sometimes, you can hear "Code Bravo" over the speakers. Maybe it’s a delay, or maybe it’s an issue with luggage. Within seconds, people stop moving, the security line freezes, and exits may even close. It’s something bigger.

Code Bravo is the emergency phrase used by airport security and the Transportation Security Administration to signal a serious security threat, such as an unattended bag, a breach at a checkpoint, or someone slipping into a restricted area. The term comes from the international phonetic alphabet used in aviation and military communications, where "Bravo" represents the letter B. When this is called, security staff immediately lock down affected areas, stop screening lines, and search for the source of the threat. To passengers, it’s sudden and confusing, but to security, it’s a carefully rehearsed response.

You are heading back to your cabin on a cruise ship when the speakers announce, "Code Alpha, Deck 7." You may think Alpha is related to the captain, but that’s not the case. It means someone on board is suffering a medical emergency.

The phrase comes from the NATO phonetic alphabet, where "Alpha" represents the letter A. In maritime emergency jargon, it became shorthand for a Priority A medical situation requiring immediate response. Cruise lines such as Royal Caribbean and Disney Cruise Line commonly use the term, though some ships use variations like repeating "Alpha" three times. Once the code is announced, onboard medical teams rush toward the specified deck or cabin. If necessary, stretcher crews are mobilized, and in severe cases, the ship may even divert course toward the nearest port for emergency evacuation. Passengers are enjoying the views, but the staff is running to save a life.

Anyone who remembers the CB radio craze of the 1970s probably smiles when they hear "10-4." Movies, truckers, and radio fans turned those number codes into a part of American culture. So if you overhear "10-33" on a police scanner, you might assume it’s just another routine message. But it’s not as simple as it sounds.

The 10-code system was first created in 1937 by Illinois State Police communications director Charles Hopper and later standardized by the Association of Public Safety Communications Officials, better known as APCO. Officers needed short phrases they could understand clearly over crackling radio signals. The 10-33 code commonly means an officer needs emergency assistance. In some departments, it also signals radio silence so dispatchers can focus on the crisis unfolding in real time.

Disney World is amazing, the parks offer something for everyone, and there are things to see wherever you look. But that’s exactly the kind of place where a child can easily disappear into a sea of strollers, balloons, characters, and crowds. For that reason, Disney has developed the "Signal 70," which alerts cast members and security that a child has become separated from their family.

The number comes from older police and emergency radio systems, where "70" was commonly associated with missing persons. Disney adopted the phrase because it allows employees to communicate discreetly without frightening or alarming nearby guests. If a member finds the child, they gently -and magically- escort them to Baby Care Center, where they coordinate the reunion.

Cruises are great to relax, enjoying a good book under the sun with a nice drink by the side. Until you hear "Echo, echo, echo" on the speakers. If you do, something is happening somewhere else on the ship.

The code is used among cruise employees to signal that dangerous winds or a navigational hazard are affecting the ship. It comes from the international maritime phonetic alphabet, where "Echo" stands for the letter E. In maritime signalling, the letter traditionally means "I am altering my course to starboard." And, in time, the phrase became associated with urgent ship maneuvers and weather-related warnings. However urgent, the repetition of the word by three doesn’t represent life-threatening situations. It alerts the crew of a certain hazard to prepare while avoiding panic among passengers.