A hairy business

Let your hair down: 10 amazing facts about human hair

Image: Ali Pazani

The human body is incredible, from its mechanics to its ability to heal and adapt to multiple environments and situations. Hair, as part of our body, is no exception to this complexity and wonder. Let’s take a look at 10 amazing facts about our hair that you may not know!

Image: Ian Talmacs

The word hair is used to describe two separate and distinct components: the follicle and the shaft. The follicle—what we commonly refer to as the root—is a living organ located in the dermis of the scalp. It’s responsible not only for growing hair but also for helping regenerate skin after a wound.

On the other hand, the shaft—often referred to as the strand—is a filament composed of layers of keratin, the same protein that makes up our nails. Unlike the follicle, the hair shaft is technically dead because it consists of dead cells.

Image: Joyful Bird

Each hair strand is composed of three layers. The innermost layer is the medulla, and even scientists are still uncertain about its exact function. Surrounding the medulla is the cortex, which absorbs water and provides strength to the strand. The cortex also contains melanin, the pigment that determines hair color, and its shape plays a major role in whether hair is straight or curly. The outermost layer is the cuticle, which serves primarily to protect the hair shaft.

Image: Tyler McRobert

Hair color is primarily influenced by several genes, including MC1R, which plays a key role in melanin production. However, not everyone produces the same type or amount of melanin. Higher amounts of melanin result in black hair, while varying levels and types of melanin—along with genetic variations—produce brown, blond, and other shades.

Red hair, the rarest natural color, is caused by a mutation in the MC1R gene and is inherited in a recessive pattern. This means a person must inherit two copies of the mutated gene (one from each parent) to have red hair, though many people carry the gene without expressing the trait.

Image: William Warby

Growing at a rate of about 0.2 to 0.5 inches per month, hair is the second-fastest growing tissue in the human body—surpassed only by bone marrow. This rate is influenced by factors such as genetics and ethnic background. Other variables, such as age, lifestyle, or health, can also have an impact on our hair growth and density.

Image: Sohan Rahat

We usually think of cats or dogs when it comes to shedding, but humans also shed hair regularly. After all, hair is a trait shared by all mammals. The average person sheds between 50 and 100 strands of hair per day, though this number can increase in response to stressors such as illness, hormonal changes, or emotional stress. Once the stress subsides and the body readjusts, the excess shedding typically stops.

Image: Joseph Chan

Commonly associated with aging, grey hair isn’t a color in itself but rather the result of a loss of pigment. As part of the natural aging process, melanin production in the hair follicle gradually decreases and eventually stops, causing strands to appear grey or white.

Genetics and ethnic background play a major role in determining when and how the greying process begins. Some people are even genetically predisposed to start greying at a very young age.

Image: Jaroslav Devia

Hair texture is commonly associated with ethnic background, but that’s not the only factor involved. Texture is primarily determined by genetics, and while genetics are closely tied to ancestry, all hair textures can be found across different populations.

Scientists believe that hair texture—specifically curl pattern and volume—is a result of the shape of the shaft. A round shaft typically produces straight hair, while flatter or more oval-shaped shafts tend to create curls and waves.

Image: Amritanshu Sikdar

Depending on the structure of your hair cuticle, your hair may be more or less water-repellent. Hair shafts with a more porous cuticle absorb water easily but also lose moisture quickly. In contrast, shafts with a tighter-packed cuticle struggle to get wet and are slow to dry.

Image: Sonja Langford

Hair doesn’t grow continuously or all at once—each strand follows a cycle with distinct phases. First comes the growing phase, which varies depending on the type of hair (for example, facial hair grows faster and for a shorter period than scalp hair). Eventually, growth slows down, and the strand detaches from the root.

After this, the hair enters a resting phase, during which it remains in place until it is naturally shed. At any given time, we have hairs in all stages of this cycle, which is why we regularly shed hair without going bald.

Image: Hans Reniers

Like any other part of the body, hair contains DNA and genetic material, which means a person can be genetically identified from a single strand, provided it includes the root. But hair holds even more information. The analysis of a hair strand can reveal substances that were present in a person’s bloodstream over time, including vitamins, minerals, medications, alcohol, and other substances.

Hospital secrets

What is a "Code Gray" and what you should know if you hear it at the E.R.

A trip to the emergency room can be stressful enough without hearing doctors and nurses speak a language that sounds like a secret code. One minute, someone is asking for medication "STAT," the next there’s a "Code Gray," and another patient is suddenly "NPO." What do those words really mean? Some are official medical terms, others are insider slang, but they all help hospital staff communicate quickly when every second counts. Here are 10 of those codes explained.

The E.R. can be hectic and unpredictable. Most patients are frightened or uncomfortable, but now and then someone becomes aggressive because of pain, confusion, mental illness, or the effects of alcohol or other substances. That’s when you can hear "Code Gray" announced over the speakers.

The code is used to summon security officers to help manage a violent or combative situation. While color codes vary from one hospital to another, Code Gray commonly signals that staff needs extra assistance to protect patients, visitors, and healthcare workers. Even if you know it now, most people in the waiting room never know what happened, and that’s exactly the point.

You have a scheduled surgery, you’re in your bed waiting to be taken to the surgery room, and you ask for a cup of coffee to make the wait lighter. The nurse will probably tell you you’re an NPO. You may think it’s serious, but it’s simply a procedure.

"NPO" is an abbreviation that comes from the Latin phrase Nil Per Os, which means "nothing by mouth." It tells patients they cannot eat, drink, or sometimes even take medication until doctors say it’s safe. The rule is most common before surgery or certain medical tests, when food or liquids could increase the risk of complications or alter the results. It may be frustrating, but it’s an important part of keeping patients safe.

You’ve probably been through the experience of visiting an emergency room, either to get checked or to visit a loved one. In that part of the hospital where everyone is rushing to save lives, you’ve probably heard a doctor asking for the R.C.P. cart or medication "STAT!" It sounds urgent, and that's because it is.

The expression comes from the Latin statim, which means "immediately" or "without delay." Hospitals have used Latin medical terms for centuries, but STAT is one of the few that remains part of everyday conversation. When a doctor says it, the request jumps to the top of the priority list. It doesn’t always refer to a life-or-death situation, but it does mean the medical team needs something done as quickly as possible.

Newborns are always a reason to celebrate at the hospital. Parents usually rest happily next to their child as they receive congratulations from close relatives. However, the hospital is always prepared to handle extremely rare emergencies under "code pink."

If you hear a "Code Pink," it usually means a baby or young child is suspected of being abducted from the hospital. Within seconds, security officers respond, exits may be monitored or blocked, and staff begins following carefully rehearsed procedures. Although different hospitals sometimes use different color codes, Code Pink has become widely recognized across North America as one of the most serious alerts a hospital can issue.

If you’ve ever spent a few days in the hospital, you’ve probably noticed that some patients are walking up and down the halls, while others need help just getting out of bed. When a nurse refers to someone as a "walkie-talkie," it’s actually good news.

This informal expression refers to patients who can walk on their own, use the bathroom without assistance, and handle most basic tasks independently. It’s not an official medical term, of course, but it’s commonly used among healthcare workers because it quickly tells the next shift that the patient requires less hands-on care than many others.

As nurses change shifts, you’ll often hear them give a quick report about each patient. One person may only need medication, while another is described as a "total."

The term is short for a patient who requires total care. They may need help eating, bathing, getting dressed, turning in bed, or moving from one place to another. Although the expression sounds impersonal, it’s simply a practical way for caregivers to communicate how much assistance someone needs.

Most people hear "frequent flyer" and think of an airline reward program. And that’s correct, but in an emergency room, the phrase has a very different meaning.

A frequent flyer is an informal nickname for patients who repeatedly return to the hospital, often due to chronic illness, recurring medical conditions, or other ongoing health issues. Behind the light-hearted nickname is often a difficult reality. Many of these patients are simply dealing with medical problems that require regular emergency care, and the expression is just a way to make the experience a bit lighter among the familiar faces of doctors and nurses.

Not all codes are for patients. The next time you’re in a hospital, look closely at what the nurse is pushing from room to room. It may look like a small rolling desk with a computer on top. Staff often call it a "WOW," short for "workstation on wheels."

As hospitals switched from paper charts to electronic medical records, these mobile computers became essential. Nurses use them to review test results, scan medications, update patient charts, and check doctors’ orders without leaving the bedside. The name sounds funny, but the technology helps caregivers spend more time with patients instead of walking back and forth to a nursing station.

After getting a shot or having blood drawn, most patients never think about where the used needle ends up. It certainly doesn't go into an ordinary trash can.

Hospitals place needles, scalpels, and other sharp medical instruments into special containers designed to prevent accidental injuries. These sturdy, puncture-resistant boxes are sealed when full and safely disposed of in accordance with strict health regulations. This not only protects nurses, but it also protects cleaning crews, waste handlers, and even the public from dangerous needle sticks. It’s one of the most important safety measures in every hospital, even though most patients never notice it.

If you’ve ever watched a medical drama, you've probably seen a patient become so agitated that several staff members rush into the room. In situations like that, a doctor or nurse may ask for a "B-52." But the name has nothing to do with numbers themselves; it actually comes from a medicine.

B-52 is hospital slang for a fast-acting injection used to calm down patients who are severely combative or at risk of harming themselves or others. The nickname comes from a commonly used combination of medications that usually include diphenhydramine, haloperidol, and lorazepam. It’s strictly reserved for when other methods of calming the patient haven’t worked.