Why Do We Have Nightmares?

It’s evening, and my wife and I are tucking my son into bed. As he snuggles down into his pile of stuffed animals – he has a bunch, and all of them share his bed with him – he looks up at us. “why do we have nightmares?”

“Because your brain’s active,” my wife tells him, kissing him goodnight.

“Well, they shouldn’t give us nightmares!” he declares.

Can’t argue with that.

Nope, not really. I mean, I don’t remember my dreams with any frequency. Heck, I’m not positive I do dream most nights, although I have a vague recollection of learning that people go crazy if they don’t. But the nightmares stay with me. Even the ridiculous one where zombies flooded my condo, but they couldn’t find me because I’d climbed up on the back of my couch. Which, now that I think about it, wasn’t a nightmare precisely. I woke up more bemused than anything.

Why do we dream?

I’ve always thought that, if you described it to an alien, “sleeping” and “dreaming” would be two of the most ridiculous things you could possibly imagine. I mean, we spend about a third of our lives immobile and paralyzed, unaware of our surroundings, and hallucinating. It sounds like utter madness. And yet, we do it. Why?

Back in February 2015, Psychology Today said that “dreaming is:

  • A component and form of memory processing, aiding in the consolidation of learning and short-term memory to long-term memory storage.
  • An extension of waking consciousness, reflecting the experiences of waking life.
  • A means by which the mind works through difficult, complicated, unsettling thoughts, emotions, and experiences, to achieve psychological and emotional balance.
  • The brain responding to biochemical changes and electrical impulses that occur during sleep.
  • A form of consciousness that unites past, present and future in processing information from the first two, and preparing for the third.
  • A protective act by the brain to prepare itself to face threats, dangers and challenges.

Which of these theories is correct? Well, the answer right now seems to be “most, if not all, of them”. Our brains are complicated things, after all, and we don’t understand how and why they work anywhere as well as we’d like. As the article says, “There is not likely ever to be a simple answer, or a single theory that explains the full role of dreaming to human life. Biological, cognitive, psychological—it’s very likely that dreaming may serve important functions in each of these realms.”

So, why do we have nightmares?

It’s complicated.

All right, all right, I’ll see what I can find.

To start with, there’s The threat simulation theory of the evolutionary function of dreaming: Evidence from dreams of traumatized children, a sadly paywalled article that looks like it might give one possible explanation. Here’s what the abstract says:

The threat simulation theory of dreaming (TST) () states that dream consciousness is essentially an ancient biological defence mechanism, evolutionarily selected for its capacity to repeatedly simulate threatening events. Threat simulation during dreaming rehearses the cognitive mechanisms required for efficient threat perception and threat avoidance, leading to increased probability of reproductive success during human evolution. One hypothesis drawn from TST is that real threatening events encountered by the individual during wakefulness should lead to an increased activation of the system, a threat simulation response, and therefore, to an increased frequency and severity of threatening events in dreams. Consequently, children who live in an environment in which their physical and psychological well-being is constantly threatened should have a highly activated dream production and threat simulation system, whereas children living in a safe environment that is relatively free of such threat cues should have a weakly activated system. We tested this hypothesis by analysing the content of dream reports from severely traumatized and less traumatized Kurdish children and ordinary, non-traumatized Finnish children. Our results give support for most of the predictions drawn from TST. The severely traumatized children reported a significantly greater number of dreams and their dreams included a higher number of threatening dream events. The dream threats of traumatized children were also more severe in nature than the threats of less traumatized or non-traumatized children.

Now, I’m not a psychologist or a neuroscientist, but “threatening dream event” sounds like a technical term for “nightmare”. So, speculating entirely from the abstract and wishing I could read (and try to make sense of) the article, it seems entirely reasonable that nightmares are – among other things – a threat response rehearsal. And I’d be curious to know if the “threatening dream events” of the traumatized children strongly related to the events that caused the trauma.

Both Psychology Today and LiveScience seem to agree, at least in broad strokes. “Most nightmares are a normal reaction to stress, and some clinicians believe they help people work through traumatic events,” reports Psychology Today, while LiveScience quotes Doctor Deirdre Barrett as saying that “Nightmares probably evolved to help make us anxious about potential dangers. Even post-traumatic nightmares, which just re-traumatize us, may have been useful in ancestral times when a wild animal that had attacked you, or a rival tribe that had invaded might well be likely to come back.”

So why am I dreaming about zombies?

Clearly, zombies aren’t a genuine potential danger, no matter how scary George Romero made them seem. Doctor Barrett, however, gave us some more information to consider: “However, some nightmares may be calling to your attention something you might do well to worry about or something that, once you are more conscious of the concern, you can convince your unconscious to stop wasting time on.”

So, I’m going to speculate here. Clearly, zombies aren’t real. Heck, for most of us, being eaten by a lion isn’t a real threat either. But your brain isn’t going to to generate a block of text in your dreams, telling you to be concerned about your spending habits and the amount of debt you’re carrying. No, it’s going to respond to your current stress in the office by trying to stage a dry run threat response drill. By making you practice running from popsicle-men wielding pinking shears for three virtual days. Because, your brain assumes, you’re obviously needing to run from something.

Do we go crazy if we don’t dream?

Well, the (fictional) Russian Sleep Experiment notwithstanding, the answer is pretty much “no”. At least, according to Harvard University. Mostly, when you don’t sleep, you get tired. Obvious, right? Well, that lack of sleep causes you to make poor decisions. Increased accidents are common, as are lack of focus and higher-level cognitive functioning – that’s concentration, memory, and the ability to do math and even reason logically.

But that’s sleeping. What about dreaming? Well, according to the Encyclopedia Britannica online, animal experimentation has revealed heightened levels of sexuality and aggressiveness after REM-sleep deprivation. Beyond that, there isn’t a whole lot of impact. In fact, there appears to be some value to REM sleep deprivation as a treatment for depression. So, no. You won’t go crazy. Just horny and aggressive and too tired to act on it.

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What Are Cataracts?

This question came up because my son’s babysitter is fostering a blind dog – an adorable little black poodle with milky white eyes named Rosie.

Seriously. How cute is that?

My son and his babysitter’s two children love her and spoil her and carry her around, and they describe her as having “moon eyes” because they sort of look like full moons. The Peppermint Pig Animal Rescue was going to get her eyes operated on to remove the cataracts, but it turns out she also has detached retinas. So the surgery wouldn’t really change anything for her.

We were talking about the dog, and the news, and my son asked “what are cataracts?” Because we’d used the word and he didn’t know it.

“It’s what makes Rosie’s eyes white,” my wife replied.

“But what are they?” he replied.

“It’s…” My wife thought for a second. ‘It’s like a film on her eyes, that she can’t see through.”

“But why are they called that?” my son persisted.

So. What are cataracts?

This. This is a cataract.

I’ll be honest, here. I don’t actually know. My wife’s explanation seemed as good as any, and I think I always sort of assumed that they were something like scar tissue. But, like with so many other things, I’ve never really stopped to ask what they were or what causes them. So, since my son asked, it’s time to change that.

Definition

Merriam-Webster, my go to for dictionaries thanks to a handy app, gives two definitions for “cataract“:

  1. [Middle English, from Medieval French or Medieval Latin; Medieval French catharacte, from Medieval Latin cataracta, from Latin, portcullis] : a clouding of the lens of the eye or of its surrounding transparent membrane that obstructs the passage of light
  2. a obsolete : waterspout
    b : waterfall; especially : a large one over a precipice
    c : steep rapids in a river the cataracts of the Nile
    d : downpour, flood cataracts of rain cataracts of information

I’m guessing that the medical term is used explicitly because of the “portcullis” meaning in Latin, since cataracts more or less block light from entering the eye. The Online Etymology Dictionary seems to agree, so that makes me feel better.

The medical condition

Multiple online sources (the Mayo Clinic and the American Academy of Ophthalmology to name just two) agree with the Merriam-Webster definition. Cataracts are a clouding of the lens of the eye. This can result in blurry vision, seeing double, light sensitivity, having trouble seeing well at night, needing more light when reading, seeing “halos” around lights, and seeing bright colors as faded or yellowed. They are the most common form of vision loss in people over the age of 40, and the single most common cause of blindness in the world (in the US alone, more than 22 million people have cataracts).

Aging is the most common cause of cataracts, because the proteins in the lens of your eye will denature over time. This is not a good thing, because your lens is made of living cells and denatured proteins disrupt the cells and can even kill them. Diabetes and high blood pressure can accelerate the process, as can ultraviolet light (UVB, specifically) and other radiation and blunt trauma to the eye. There is a genetic component to the development of cataracts as well, particularly if someone develops them in childhood or as young adults. These aren’t the only causes, of course. Just the most common.

The most common forms of cataracts are subcapsular, nuclear, and cortical. Subcapsular cataracts start at the back of the lens, and are most common in diabetics and people taking medical steroids. Nuclear cataracts start in the center of the lens, and are most commonly associated with aging. Cortical cataracts start at the edge of the lens and work inwards ina “spoke-like fashion”. There are also congenital cataracts, which you are born with or develop during childhood – usually due to your genes or some form of infection or trauma.

Treatment

Ultimately, the only treatment for cataracts is to remove the existing lens and replace it with an artificial lens called an intraocular lens that matches the prescription (if any) that you need for your glasses. The intraocular lenses come in a wide variety of different types, and if you need one you should consult with your ophthalmologist to see which ones make the most sense for you.

Surgery is generally considered a last resort, though. As long as the cataract symptoms aren’t bothering you, and the problems with your vision can be corrected with glasses, there generally no need to undergo surgery. Cataract surgery is considered pretty routine, but the only really risk-free surgery is one that you don’t have.

Hang on, hang on. This is all about people. Didn’t this start with a dog?

Yep. But cataracts aren’t limited to humans. It’s a condition caused by disruption and damage to the lens of the eye, so any animal with an eye with lenses can develop cataracts. There’s a lot of information on the internet about dog cataracts, and mentions of cats. One veterinarian stated that they are “the most common cause of blindness in dogs, and can also affect people or any species of animal”. Like humans, animal cataracts can develop from age, diabetes, trauma, genetics, or something called Progressive Retinal Atrophy – the name for a cluster of generic disorders that cause the retina to degenerate. Animal cataracts can be treated in the same way as human cataracts. Progressive Retinal Atrophy has no treatment, though.

Impaired vision and even blindness aren’t a death sentence for a house pet, though. Rosie gets around just fine, as long as you don’t move her food and water dishes and rearrange the furniture a whole lot. So if you live in the Cincinnati area and want to adopt an adorable little blind dog (or another animal), contact the Peppermint Pig Animal Rescue. They’ve got a lot of animals looking for a loving new home.

If My Hand Set On Fire, Would It Hurt?

I don’t actually remember where this question came from, or why my son asked it. I mean, I suspect it was inspired by playing a video game. Or maybe from watching cartoons. I just have “If my hand set on fire, would it hurt? How bad?” in my notes, with no context whatsoever.

That happens, sometimes. I’ve got a bunch of questions I jotted down, and many of them lack context. But, in this case, it makes a fun follow-up to my last article.

Sources of burns

To start answering his question, let’s start with how you can get burned. More things than just fire can burn you, after all – just ask your skin, after a day at the pool without sunscreen. In fact, the John Hopkins Medical Library provides four different sources of burns:

  • Thermal burns. These burns are due to heat sources which raise the temperature of the skin and tissues and cause tissue cell death or charring. Hot metals, scalding liquids, steam, and flames, when coming into contact with the skin, can cause thermal burns.
  • Radiation burns. These burns are due to prolonged exposure to ultraviolet rays of the sun, or to other sources of radiation such as X-ray.
  • Chemical burns. These burns are due to strong acids, alkalies, detergents, or solvents coming into contact with the skin or eyes.
  • Electrical burns. These burns are from electrical current, either alternating current (AC) or direct current (DC).

So, if my son’s hand was to be set on fire, he’d experience a thermal burn. Alternately, if he got a sunburn he’d have a radiation burn, if he poured lye on his hand he’d have a chemical burn, and if he stuck his finger in a live lightbulb socket he’d get an electrical burn. He’d also have parents doing their best to stay calm until he was taken care of, but that leads into an entirely different question of the “would you still love me if I did something stupid?” type.

(For the record, he’s never actually asked that question. But the answer is: “Yes, I would. I might not be happy with your behavior, but I’d still love you. Now take your fingers away from that electrical socket.”)

Ultimately, each of these sources of burns has some unique characteristics. But they all have the same basic effects.

Let’s talk about skin

Your skin has three layers: the epidermis, the dermis, and the hyodermis. The epidermis is the outer layer, composed of four to five layers of skin cells that protect the underlying layers. These cells manufacture and store keratin, a tough and fibrous protein that also (in a slightly different form) makes up our fingernails and hair and the horns of a rhinoceros. The epidermis also contains the skin pigment melanin, meaning that much of our conceptions of race aren’t even skin deep. The living layers of the epidermis are covered with layers of dead, keratinized cells that flake off over time. Beneath the epidermis is the dermis, two layers of connective tissue that contain blood and lymph vessels, nerves, hair follicles, sweat glands, and other structures. Finally, the hypodermis is connective tissue filled with more blood vessels and subcutaneous fat that serves to connect the skin to the bones and muscles.

“Solid burn, Branch.”

Returning to the John Hopkins Health Library, we learn that there are three classifications of burns – and you’ve probably heard what they are: first-degree, second-degree, and third-degree. Each of these relates to how deep the burn penetrates into the skin. First-degree burns are also referred to as superficial burns, and only affect the epidermis. It’ll be red and painful, dry to the touch, and lacking blisters.

Second-degree burns are also referred to as partial thickness burns, and both the epidermis and dermis are damaged. The skin will still appear read, but it is likely to be blistered and swollen.

Third-degree burns are also called full thickness burns, and this is where it gets really bad. The hypodermis is also damaged in a third-degree burn, and parts of the body below the hypodermis may also be involved. Parts like muscles, tendons, and bones (some sources call this a fourth-degree burn when this occurs). Third-degree burns will look whie or charred, and there tends to be no feeling in the burn site. Why? because the nerves have been destroyed.

Burns are further classified by burn percentage, which estimates the total area of the body affected by the burn. This is done on a “rule of nines”, in which body coverage is estimated in multiples of 9.

The chart doesn’t call out a hand specifically, but it would probably be considered 4.5%.

How much would it hurt?

There are a number of pain scales. The one I found first, and will be using as an example, ranks from 1-10 (well, technically 0-10, but 0 is “No pain. feeling perfectly normal.”). So, here’s the levels:

  1. Very light barely noticeable pain, like a mosquito bite or a poison ivy itch. Most of the time you never think about the pain.
  2. Minor pain, like lightly pinching the fold of skin between the thumb and first finger with the other hand, using the fingernails. Note that people react differently to this selftest
  3. Very noticeable pain, like an accidental cut, a blow to the nose causing a bloody nose, or a doctor giving you an injection. The pain is not so strong that you cannot get used to it. Eventually, most of the time you don’t notice the pain. You have adapted to it.
  4. Strong, deep pain, like an average toothache, the initial pain from a bee sting, or minor trauma to part of the body, such as stubbing your toe real hard. So strong you notice the pain all the time and cannot completely adapt. This pain level can be simulated by pinching the fold of skin between the thumb and first finger with the other hand, using the fingernails, and squeezing real hard. Note how the simulated pain is initially piercing but becomes dull after that.
  5. Strong, deep, piercing pain, such as a sprained ankle when you stand on it wrong or mild back pain. Not only do you notice the pain all the time, you are now so preoccupied with managing it that you normal lifestyle is curtailed. Temporary personality disorders are frequent.
  6. Strong, deep, piercing pain so strong it seems to partially dominate your senses, causing you to think somewhat unclearly. At this point you begin to have trouble holding a job or maintaining normal social relationships. Comparable to a bad non-migraine headache combined with several bee stings, or a bad back pain.
  7. Same as 6 except the pain completely dominates your senses, causing you to think unclearly about half the time. At this point you are effectively disabled and frequently cannot live alone. Comparable to an average migraine headache.
  8. Pain so intense you can no longer think clearly at all, and have often undergone severe personality change if the pain has been present for a long time. Suicide is frequently contemplated and sometimes tried. Comparable to childbirth or a real bad migraine headache.
  9. Pain so intense you cannot tolerate it and demand pain killers or surgery, no matter what the side effects or risk. If this doesn’t work, suicide is frequent since there is no more joy in life whatsoever. Comparable to throat cancer.
  10. Pain so intense you will go unconscious shortly. Most people have never experienced this level of pain. Those who have suffered a severe accident, such as a crushed hand, and lost consciousness as a result of the pain and not blood loss, have experienced level 10.

I couldn’t find any pain chart rankings for burn pain, partially because pain is a subjective (although real) phenomena. The Chicago Clinic explains, however, that

Burn pain can be one of the most intense and prolonged types of pain. Burn pain is difficult to control because of its unique characteristics, its changing patterns, and its various components. In addition, there is pain involved in the treatment of burns as the wounds must be cleansed and the dressings changed. Studies have concluded that the management of burn pain can be inadequate, and such studies have advocated more aggressive treatments for pain resulting from burns. Lastly, some burns can be mentally traumatic and/or physically disfiguring and lead to psychological pain that must be addressed, as well.

So there’s that.

What Are Vocal Cords?

“Dad?” my son asks. “Why does Darth Vader sound funny?”

We’re sitting on the couch when he asks the question. I’m reading, and he’s playing with his Legos, and the question doesn’t come from as far out of left field as it might seem. The majority of his Legos are Star Wars themed, after all. “Because the people who made the movie wanted him to sound scary,” I say.

“No,” he huffs. “I mean, in the movie!”

“Oh,” I say. “Well, his vocal cords got hurt when he fought Obi Wan.”

“Vocal chords?” he asks, sounding baffled. “What are vocal chords?”

What Indeed?

I don’t know, to be honest. Oh, sure, I know they’re the things in your throat that vibrate when you talk, and that they’re the things that actually let you speak. But I have no idea beyond that. The name always made me imagine a set of fleshy guitar strings stretched across my throat – when I thought about it at all – but I’m fairly confident that this isn’t correct. So, let’s look into the answer. Literally.

Vocal Cords

Those are vocal cords – also known as vocal folds – in action. Medscape describes them as “mucous membrane infoldings that stretch horizontally across the middle laryngeal cavity. They are attached anteriorly at the angle on the interior surface of the thyroid cartilage and project posteriorly to the arytenoid cartilages on either side.” They’re found within the larynx, at the top of the trachea, and open when inhaling and close when swallowing. They also close to help vibrate and modulate air expelled from the lungs to enable us to produce sounds (like, for instance, speech).

illu_larynx

Technically, there are two sets of vocal cords. The “true vocal cords” (or vocal folds) and the “false vocal cords” (or vestibular folds). These vestibular folds primarily serve to protect the more delicate vocal folds, but may also be “used in the production of deep tones and screaming or throat singing”. So, if you happen to enjoy black metal or Tuvan or Mongolian throat singing, you have heard and appreciated the false vocal cords.

On average, adults have larger vocal cords than children and men have larger vocal cords than women. This is why, again on average, adults have deeper voices than children and men have deeper voices than women. Larger vocal cords vibreate more slowly and with a longer frequency, creating lower sounds. Women are also more likely to have vocal folds that appear to be a pearly white, while men are more likely to have pinkish vocal cords.

Human are not born with fully developed vocal folds. Infants lack a vocal ligament, which allows the muscles of the larynx to easily control the vocal folds. “The vocal ligament begins to appear at about 4 years of age. The formation of the 3 defined lamina propria layers occurs between the ages of 6 and 12 and are fully mature at the end of adolescence.”

Care to tie this back to Star Wars?

Of course I would, because that’s what spawned this question. Clearly, the vocal cords can be damaged – acid reflux and smoking can thicken them, and significant use can stiffen them. Stiff vocal cords don’t vibrate as well, reducing vocal range and making speech difficult. Surgeons can repair this stiffness by replacing the vocal cords with synthetic materials. Specifically, a variation of polyethylene glycol called PEG30, which mimics the flexibility of human vocal cords and moves in a very similar manner to the natural tissues that compose them. So, instead of having a raspy mechanical voice, Darth Vader could have been given an amazing singing voice.

Not that the Dark Lord of the Sith doesn’t rock out anyway.

There’s Creepy Stuff In My Ears!

Not too long ago, we had to clean my son’s ears out. When I was a child, this involved q-tips. There have been all kinds of advances since then, though, and now we use drops that get flushed out with warm water.

My son hated it. Not because it hurt, mind. But he had to lay down for a full minute per ear, with a washcloth on his ear, and he was bored. Then, after we rinsed out the ear, he looked at what came out. “There’s creepy stuff in my ear!” he said.

“That’s just ear wax,” I told him.

“What’s ear wax?”

Uhm…

Seriously? Last week wasn’t enough for you?

Look. Ear wax is a fact of life. I have it, you have it, famous actors and supermodels have it. Everyone has it. But, how many of us know what it actually is or what it is for? I sure don’t. And I promised my son I’d answer his questions. So, we’re going to start with glands.

Glands

Your skin has glands, which are organs that synthesize some substance and then release that substance for use by the body. Chief among them are the sebaceous glands, found everywhere on your skin except for the hands and the soles of the feet. These sebaceous glands secrete an oily or waxy substance called sebum, which lubricates and waterproofs your skin. Sebum is also slightly acidic, and helps serve as a barrier to viruses and bacteria.

howdowehear

Along with sebaceous glands, the outer third of your ear contains ceruminous glands. These glands produce cerumen, which helps you hear by keeping your eardrum pliable. It also helps keep the external auditory canal clean, and serves as another barrier to bacteria and foreign particles.

Earwax

Earwax is a mixture of sebum and cerumen and all the things block and trap: dirt, bacteria, shed hair and skin cells, and so on. People of African and European origin are likely to have wetter cerumen (and wetter, dark brown earwax), while Asians and Native Americans will have dryer cerumen (and dryer, grey or yellow earwax).

Normally, earwax helps to clean the ear canal by a process of “epithelial migration”. Cells in the ear canal are pushed outwards by the growth of new cells, and earwax – being sticky – clings to the cerumen and sebum produced by the glands and moves with the cells. Eventually it is pushed to the outside of the ear and out, taking dead skin cells and dirt and bacteria with it.

Excess Earwax and Blockages

According to the Mayo Clinic, excess earwax is caused by the ear secreting excess ebum and cerumen. Or, in other words, excess earwax is caused by excess earwax. Go figure. If you have excess earwax, it can be softened with a few drops of mineral oil or hydrogen peroxide, and then – after softening for a day or so – rinsed out (gently) with warm water. They recommend that you never attempt to dig it out, as that can push the wax deeper and block the ear canal or even damage the eardrum. If you can’t clean it out yourself, you should see a doctor.

Why Do We Get Boogers?

It’s winter, and the temperature has been really strange. Up and down, up and down. One day I can walk around outside, thinking my light jacket is too much coat. Two days later, it’s snowing. It’s been that kind of season, and I think that’s why my son has the sniffles. He’s not sick, per se, but he’s sniffling and sneezing and his nose is running. So recently, he goes and grabs a tissue and wipes his nose. “Dad,” he asks, “why do we get boogers?”

Well, I did say I’d answer his questions…

the-nose

What is a booger?

Let’s be honest here. You know what a booger is. You were a kid once, even if you haven’t been around any recently. Still, let’s do this right. Merriam-Webster gives two different definitions for the word “booger“:

  1. Bogeyman
  2. a piece of dried nasal mucus.

Clearly, in the contex of my son’s question, we’re talking about the second definition. I’ve never told him about the “bogeyman”, and I don’t think any of his friends have told him about that character. He’s six, and he’s feeling scared of the dark, so I think it would have come up if he had. So, let’s focus on the dried nasal mucus. The Online Etymology Dictionary gives the following explanation for the word

“nasal mucus,” by 1890s; earlier bugger. Also boogie.

So, yeah. No Greek or Latin or Proto-Indo-European here.

What is mucus?

Going back to Merriam-Webster, mucus is defined as “a viscid slippery secretion that is usually rich in mucins and is produced by mucous membranes which it moistens and protects”. It’s a fairly common fluid produced by the human body – heck, by nearly every animal, not just us humans. The respiratory system produces mucus in the nose, the airways (i.e. your sinuses and throat), and the lungs, as a way of trapping foreign particles. What foreign particles, you ask? Dirt. Dust. Bacteria. Pollen. Allergens. You name it, your mucus traps it. And the more your respiratory system needs to trap, the more mucus it produces. That’s why you generate more mucus (and then cough) when you get exposed to allergens or you get sick. Your body is trying to trap more of the foreign particles and expel them before they can cause you more problems.

Your respiratory system isn’t the only place that makes use of mucus, however. Your digestive system uses it for the whole length – from the esophagus into the stomach and the intestines and into the colon – as a way of lubricating your food in its journey through your body. It also shows up in the reproductive system, functioning as a lubricant and a means of transporting sperm and eggs through the body. Your eyes generate mucus as well, lubricating and protecting sensitive cells and keeping them moist.

So. How does mucous become boogers?

Bear in mind that mucus isn’t just water. It’s full of proteins and antibodies (because it isn’t just a passive defense) and electrolytes, not to mention all the dust and dirt and bacteria and such that it has trapped. As the water in the mucus evaporates or gets absorbed by the body, these solids get left behind, sticking and clumping together until – if not disturbed – they form masses of noticeable size.

I can’t believe I’m going to ask this, but… why the nose? Why not eye boogers?

Actually, those can happen. Eye crust, also known as rheum, is essentially eye boogers.

Great. Anything else?

Yeah. You know how your mom said you shouldn’t pick your nose and eat it?

Do I want to know this?

Hey, you’re the one still reading.

It turns out that there’s a hypothesis that boogers have a sugary taste that is meant to entice you to eat them. Because the act of doing so helps introduce weakened pathogens from the environment to your immune system, building up your defenses. This is rather controversial (not to mention nauseating), and it has not been tested. A number of scientists als point out that you swallow mucus all the time, just by living. This still serves to introduce the pathogens to your body. So don’t take this as a license to go to town on your nose, please.

I wasn’t planning to. Also, I hate you so very, very much right now.

Look, the human body is endlessly fascinating. Even the bits that we find culturally repugnant. Besides, you’re the one reading the article about boogers. What did you expect?

A Little More On The Purple Eye

The day I posted “Do I Have A Purple Eye?“, a friend of mine made the following comment on Facebook:

Aha! You, sir, are incorrect. You forgot cerebral contusions which don’t leak into skin tissues but into surrounding brain tissue.

Well, this got my attention (and made my skin crawl). More importantly, it got me looking deeper into this whole ‘contusion’ thing. Buckle in, folks: this will be uncomfortable.

Not all hematomas are created equal

To begin with we’ll need to revisit some definitions, because I wasn’t entirely correct. Broadly speaking all bruises are hematomas, but not all hematomas are bruises. This is because a hematoma is just (“just”) a collection of blood outside the blood vessels, which can be caused by trauma, illness, or just the blood vessel tearing from weakness. Contusions are a specific subset of hematoma caused by blunt trauma.

black-eye

According to Wikipedia, hematomas come in several flavors. These include:

  • Subdermal, which is a hematoma beneath the skin.
  • Skull/brain, which are hematomas where blood pools either within the brain itself or in the cerebrospinal fluid that cushions your brain within your skull. Subdermal hematomas of the scalp also get classified as skull/brain hematomas.
  • Breast, which is a hematoma within the breast tissue – meaning that women are much more prone to these than men.
  • Myocardial, which is a hematoma in your heart muscles.
  • Pulmonary, which is a hematoma in your lung tissue.
  • Subconjunctival, which is a hematoma of the conjunctiva – the tissue that lines the inside of your eyelid and covers the whites of your eyes.
  • Perichondral, which is a hematoma of the ear. Specifically, it is blood pooling in such a way that the ear cartilige seperates from the perichondrium (the connective tissue that surrounds the cartilige of developing bone). This is where so-called “cauliflower ear[https://en.wikipedia.org/wiki/Cauliflower_ear]” comes from.
  • Perianal, which is a hematoma of the anus. This is also known as a hemorrhoid.
  • Subungual, which is a hematoma beneath a fingernail or toenail, and is sometimes known by names such as “runner’s toe” or “skier’s toe”.

Hematomas are also classified by degree. A petechiae is less than 3 mm in diameter, a purpura (which I mistakenly thought was a type of hematoma, instead of a degree) is between 3 mm and 1 cm in diameter, and an ecchymosis is larger than 1 cm in diameter. So a petechiae subdermal hematoma is a tiny thing on your skin, while a perianal ecchymosis is no diagnosis you ever want to have.

Now, a contusion is just (just?) a hematoma caused by our old friend blunt force trauma. So, really, any type of hematoma can be a contusion. Myocardial contusion? Sure. Perianal contusion? Yep. Perichondral ecchymosic contusion? Why not.

So there you have it. Anything that has blood vessels in or near it can suffer a hematoma. Skin, heart, lungs, eyes, whatever.  And now I’m going to pack myself in cotton for a while.  Just until the skin crawling and the paranoia wears off.