Blood – Our Private Universe

milkywayWhile you read this article up to 6 liters of blood are passing through every vessel of your body. Of course, in the states we don’t really do the metric thing. So what does that mean? You have a volume of blood equal to almost 17 cans of Coke (or Pepsi depending on which diner you’re in). You could also say you have a volume of blood equal in weight to six large orders (quarts) of pork fried rice, but I like to keep my takeout preferences separate from matters of science.

What about our red blood cells? A fit, health conscious individual of my height and build (5’6, 175Ibs) can have from 4 to 6 million cells per microliter or 4 to 6 trillion per liter. So 20 microliters of blood would form a drop just large enough to cover up the word “Big” on a page. That single drop of blood holds a red cell population nearly equal to that of Mexico (roughly 120 million). Each one of those red cell hombres y mujeres could be carrying up to 1 billion oxygen molecules. We have six liters of blood and every single cell pulls its own weight. We are a universe within a universe. Stay curious, stay classy, and never stop learning my friends 🙂

 

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How does CPR work anyway?

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when performing CPR make sure the camera gets your good side.

I don’t know about you, but I’ve spent far too many precious Saturday mornings renewing my CPR certification, kneeled over a motionless, plastic manikin. What does CPR actually accomplish? What purpose does locking lips with a complete stranger and pushing down on their thoracic cavity (like it owes you money) serve anyway? Let’s dive into the physiology of CPR shall we.

What’s the point?

The ultimate purpose of CPR (cardiopulmonary resuscitation) is to re-oxygenate the blood via the lungs and circulate that blood throughout the body by manually compressing the heart. Ideally, the re-oxygenated blood will reach the brain and restore consciousness.

First let’s take another look at the lungs…

Lungs are an elegantly simple respiratory organ (as organs go). From a strictly mechanical point of view, lungs are just big sacks of air. Those sacks have a remarkably air tight seal. In fact, if you perform the CPR breathing technique correctly you should be able to watch the victim’s chest rise with each full breath. That’s why we pinch the victim’s nose, tilt the head back with the chin, and form a seal with our hands around their mouth,  then blow. We are filling the lungs with air.

No, I didn’t say oxygen. I said and meant “air.” Oxygen is a pure, gas element but human beings breath a mixture of gases. So when we give the victim breaths we want them to get the oxygen they need but they are also getting the leftover CO2 from our cellular metabolism, and all of the nitrogen, argon, etc. that we took in from the atmosphere. The point I’m making is that providing the victim with adequate oxygen with just your own lung power is a lot of work and pretty inefficient. You’re saving their life but when the EMTs do arrive they will likely provide the victim with 5-10 liters of O2 per minute from a respirator.

What’s with the chest compressions?

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pace yourself

I don’t expect everyone to have as much school spirit about the human body as I do, but the heart is so well constructed, so intelligently engineered that even when it stops beating on its own it can still be used to pump blood through the body. Your heart contains chambers and valves that allow blood to flow in one direction with each compression while preventing that volume of blood from flowing backwards. That’s what a pump does. A bicycle pump let’s you exert downward force on the handle to force air directly into the tire without taking air away from the tire when you draw the lever back. So as you exert force on the breast plate blood from the heart will continuously make its way throughout the body with each compression.

So we are delivering two breaths (for an adult) every 30 chest compressions to recharge the blood with oxygen and pump it back throughout the body. We perform chest compressions at a rate of 100/minute or just faster than 1 compression per second because we are simulating a beating heart. If you need to find a rhythm think drum & bass techno or Cuban dance mix not smooth jazz.

A Race against time…

There’s a good reason why breathing is involuntary. Oxygen keeps our cells going. Forget about Kale salads and protein bars. The moment our tissues are cut off from an adequate O2 supply they begin to die (hypoxia). This is why CPR must be instinctive and started the instant no pulse is felt in the victim because the loss of organ function (especially) the brain can happen in minutes.

It won’t work without an AED

using-aedCPR can be a life saver but…not all by itself. There’s a reason the victim’s heart stopped in the first place and you can’t stay on your knees doing compressions forever. Typically there is some form of short circuit in the vital electrical activity of the heart that governs a normal heart beat. In a normal, healthy, jazzercizing heart an electrical signal forming at the top of the heart (at the SA node) contracts the upper atrial chambers, forcing the blood into the lower ventricles (bottom chambers). When that signal makes its way down the heart to the AV node, the ventricles contract, releasing blood into both the body and the lungs. An AED is used to jump-start the heart’s electrical system in an effort to stimulate the nerve impulses of the SA and AV nodes once more. Unless you’re a Jedi knight you just can’t do that with your bare hands.

Despite what you see in the movies, any victim who receives CPR is not just going to snap out of it and take the rest of the day off. They will 100% of the time need medical attention. In fact, while you’re preparing to do CPR someone should be calling 911.

Hopefully you guys will never have to use it. Let’s be honest, the thought of having to do perform CPR on a real person scares the Hell out of me. Stay curious, stay classy, and never stop learning my friends 🙂

 

 

Loud and Clear – the science of sound

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I’ll bet her hand tells the best jokes

 

You may not know this but…

we are in possession of ancient technology. I’m talking about Men in Black, Star trek phaser-level technology. Forget about your smartphone or the connectivity of your Wi-Fi to your oh so shiny tablet (yeah..your tablet is boring). We have ears! Do you understand how remarkable the phenomenon of hearing is?! Mammalian ears are a curiously sophisticated adaptation. They’ve crossed species borders and traveled the millennia just to stay virtually the same. As far as mammals are concerned, version 1.0 is still the best thing out there and those cute little ears of our furry ancestors have been around since the dinosaurs. Archaeologists in China discovered the fossil of a 195 million year old mouse-like mammal (Hadrocodium) with a fully developed inner ear, not unlike what we have today. That’s the physiological equivalent of finding King Tut’s blue-ray collection.

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Do we hear with our ears or with our brains?

Sound Waves and Philosophy

Sound is a physical property. Sound happens because people and animals and objects interact with the physical environment and the resulting energy of those interactions is transferred into sound waves that travel through air, water, asphalt or whatever. What we “hear,” on the other hand, is what our brains say we hear. Our brain translates that physical phenomenon into an experience and our brain instantly labels that experience as familiar or unfamiliar, safe or dangerous, pleasing or Nickelback.

Ear Anatomy

The pinna, that floppy, fleshy, flap of skin and cartilage on the outside of our heads is a total cover girl. It’s the most recognizable part of the ear and it helps to funnel a small portion of the infinite variety of sound waves whizzing pass our heads every second of the day. However, to learn the secret to the riddle of sound we need to look beyond the pinna, down the icky, wax filled canal (external auditory meatus) into the middle and inner ear where the tiny bones and membranes play percussion for our central nervous system.

ear-anatomy

The path of sound…

Tempanic > malleus > incus > stapes > oval window > vestibules > cochlea > Brain!

Once sound waves slinky down our ear canal they reach the tempanic membrane (ear drum) and that’s where the magic really happens. Waiting just behind the tympanic membrane is a highly specialized set of tiny bones (ossicles) that move in sync with each vibration.

At this point we have this nifty domino effect happening where vibrations move from one tiny bone to the next. That’s right, I said “vibrations.” Sound is energy and it behaves the way all energy does, never destroyed just moving from one form to another.

Anyway, vibrations move from the tympanic and then pass the baton to the malleus, along to the incus, and then to the tiniest bone of all, the stapes.

Here’s where it changes up a little. Those 3 bones I mentioned occupy this air filled space (tympanic cavity), kind of like a hallway in your head and at the end of that hallway is a door (or rather a window), the oval window. This window is a part of the next compartment of the ear. When that vibration reaches the stapes it basically knocks on that window, handing off the remaining sound energy to the inner ear.

Keep in mind that this is all happening at the speed of sound. Sound waves gallop along at a healthy pace of 1,126ft/sec through the air. Just imagine jumping 13 train cars in a fraction of a sec. Of course, your ear canal is only about an inch long so this all happens MIGHTY quick.

The inner ear is like another dimension. There are fluid filled vessels and a chamber at the end shaped like a snail shell with hairy receptor cells transmitting signals to the brain. I mean What?! It sounds like the hallucination of a band groupie at a Pink Floyd concert, but it’s real.

So what happens?

The stapes knocks on the oval window, transferring the sound vibration to fluid contained behind the window that will move along tubular ventricles.

So in case you got lost, sound moved down the pinna, through the canal, to the tympanic, shaking hands with the malleus, incus, and stapes hanging out in the hallway of the tympanic cavity where the stapes bangs on the oval window to stir up some nasty fluid on the other side.

This fluid (endolymph) now surging with sound energy, will transmit vibrations within the coiled vestibules where they connect with a spiraled chamber called the cochlea.

OK…here it is..

Tucked inside the cochlea is a layer of epithelial receptor cells that make up the Organ of Corti. As the energy charged fluid passes over the tiny hairs of these cells an electrochemical signal (neural transmitter) is released. Neural transmitters are basically like biochemical text messages, but instead of going through Verizon or Sprint this message travels down a bundle of nerves called the spiral ganglion where the temporal lobe of your brain is waiting to…well..”hear” it.

Stay curious, stay classy, and never stop learning my friends 🙂

Treading Water – The Science of Gills

Did you just get 90's goosebumps? I know I did.

Did you just get 90’s goosebumps? I know I did.

Sometimes, science lets me down in a very devastating, stood up at prom, “Santa Claus isn’t real” kind of way. That may be a surprising statement coming from yours truly but even I like to daydream occasionally without science butting in.

Here’s what happened…

I had the afternoon off. I’m sitting in my easy chair with the torn, pleather upholstery eating fried rice, watching Water World on Netflix (a B-movie classic), and generally loving life with a capital L. There’s this scene where Kevin Costner’s character is scavenging the ocean floor for trinkets to sell back at the surface of a post apocalyptic Earth and I had this rush of childhood nostalgia. Ever since I was a kid I would think “How bad-ass would it be if humans had gills?!” It just seemed like such an unfortunate detour for human evolution to move us out of the water, a medium that 71% of the Earth’s surface is covered in. For the remainder of the movie I just played “what if” scenarios out in my head. Eventually, science (specifically human physiology) stepped in to yank my head out of the fluffy clouds and bring my senses back to the boring-ass ground.

I realized that while gills are a marvel of natural selection, gills alone are simply not enough to allow human beings to breathe under water. Let me explain…

# 1 – We make lousy fish

Try not to be too negative. It’s not that we are poorly adapted to living under water but that we are perfectly adapted for living on land. We breath atmospheric oxygen (which makes up 21% of the atmosphere). Fish breath dissolved oxygen in water (which makes up a fraction of a percent). In case you didn’t know, oxygen is amazing and because we get ours in abundance our metabolism can burn hotter and longer. Since we’re mammals that typically means that a considerable amount energy goes into maintaining a constant core body temperature. Sure fish are pretty active as cold-blooded critters go; their sleek and slender bodies allow them to use less energy moving through the water, and being cold-blooded (with lower metabolic demand) their overall oxygen demand is already quite low. Humans, however, need that extra oxygen to power an engine that fish don’t have, a highly developed brain.

You could argue (I encourage that) that our dependence on oxygen is the price we pay to evolution for the gift of conscious thought. We are not just mindless clusters of cells responding to stimuli, governed by instinct, swimming in schools like minnows. We make decisions, hesitate, regret, learn, and even celebrate when we get it right. Yay humanity!

#2 Gills are not a good look for us…

The secret to gills is surface area. In case you didn’t know, anytime you have a mechanism that can fit a lot of material into a relatively small space without disrupting its functionality, scientists go “ooh, look at that surface area!” For example, within our small intestine is a vast area of protruding microvillae. These protrusions have their own unique surface and that diversity of surfaces aids in absorption.

The accordion-like folding of gills are able to effectively extract the oxygen from water by cramming in countless, minute rows of cells and vasculature. In fish, gills are the site of gas exchange and it doesn’t get anymore direct. They literally just have arteries from the heart branching into arterioles at the site of the gills. The oxygen poor blood from the heart gets juiced-up with fresh O2 from the gills that goes back into circulation. It’s creepily similar to the way our lungs work; our heart pumping O2 poor/CO2 rich blood to the lungs in exchange for the good stuff every time we inhale and exhale. Our lungs however are inside our bodies. A fish’s breathing apparatus is completely fly-open and exposed to the surrounding water for diffusion to take place and I don’t know if you’ve noticed but gills take up a lot of space on a fish. The more active the fish, the larger its gills are and the their size increases exponentially with body size. If humans had gills we’d need more than a turtle neck to cover them up when we’re hitting up the mall.

Sure sharks, dolphins and whales seem to breath just fine. Well whales and dolphins have to surface to breath through their blow holes. Sharks have gills but they have to pump gallons of water through their mouths constantly and some sharks have to move constantly to increase the flow water over their gills. I don’t know if I’d call that winning.

Oh future technology...I wish you were real!

Oh future technology…I wish you were real!

#3 Water is the problem…

The bottom line is that there just isn’t enough oxygen available in sea water to support our metabolism. Even if we could design artificial gills that did a fine job of extracting oxygen from the water (and there are many impressive prototypes out there) it wouldn’t get us very far. We can’t turn the dial down on our metabolism. Our bodies will still use energy to maintain our core temp as the colder water draws heat away.

Even if we could manage just a gasp of precious air our muscles would demand their share, rapidly yanking O2 from hemoglobin in the circulating blood as we struggle to swim, demanding even deeper breaths. Eventually our muscles would fail, burning with lactic acid from the oxygen debt.  Carbon dioxide accumulates in our body. Our gag reflex gets overwhelmed. With nowhere to escape, water drains into our stomachs and…I’m not even going to mention the resulting brain death. Did I mention the brain death?

Hey listen, don’t be so dark. We live on land! The surface is where it’s at. We have sunsets, flowers, and sooo many colors. Trust me, blue water would get really old really fast. Not to mention, we don’t have to eat soggy cheeseburgers. So close your eyes, take a deep breath (because we can) and take a moment to appreciate life on land.

Stay curious, stay classy, and never stop learning my friends 🙂

The Curious Case of Dr. Eijkman

bored-chicken-finalBefore we get started there is something you need to accept about he human body…that it is and always will be an elegant and extraordinary mystery. Whether you’re a sleek and sexy, Ashram Yoga instructor, a chiseled cross-fit enthusiast with triceps like boulders, or a 300 lb chain smoker with a mild cinnamon bun addiction your body is truly amazing. I say that with confidence because with all of the things that could go wrong with our bodies, for many of us it is “not normal” to be sick. Your body simply does it’s job and we can only grasp what a remarkable job it does when something goes wrong.

So what can go wrong?

Let’s say you robbed a vengeful fortune teller of $2,000 dollars at a poker game in Atlantic City. The next day you woke up to find that a deadly curse had been placed on you. In a matter of weeks you will begin to lose weight. You will suffer from swelling, weakness, and pain in your limbs. Depression eventually takes hold of you and you lose the capacity for empathy. Tragically, lesions begin to form in your brain resulting in epileptic attacks. Eventually your suffering ends in madness and heart failure. YOU ARE DOOMED…unless you find the anecdote. The only thing that can stop the curse before it starts, brown rice. Wait…WHAT?!  Let me explain..

You see, in Southeast Asia millions of people truly did suffer from a curse. It’s name was Beriberi, and it refers to a collage of symptoms affecting neurological and cardiac functions in many of the notoriously destructive ways I’ve already described. Then along came a crafty, Dutch physician named Christiaan Eijkman who sailed the ocean blue to Indonesia in search of answers. One day that answer came in the form of a question; “why aren’t the chickens sick?”

Beriberi was everywhere. It affected the soldiers, the villagers, and even their farm chickens. In fact Eijkman had a few chickens loitering about his clinic with similar symptoms. Well eventually he started noticing that a few of the chickens seemed to be recovering. So what changed for the chickens? Their diet changed.

The camp where Eijkman was staying had a new cook who decided that rather than waste the good rice on the chickens he would just feed them the regular ole brown rice.

The Dutch had taken over Indonesia at the time (as in the Dutch-East India Company) and they ate polished white rice (rice with its golden, outer husk removed) along with the locals. White rice has a longer storage life and when you live in a hot and humid climate in a time before water-proof, plastic containers or refrigeration, the storage life of your food is everything.

Unfortunately, when you remove that outer husk you shed the bulk of the nutrients in the rice. Our guy Eijkman proposed that there was a mystery nutrient that was “vital” for maintaining normal physiological function. That nutrient would later come to be known as thiamine (vitamin B1) an essential amino acid your body needs to build protein and carry out normal ATP synthesis and a grocery list of metabolic pathways.

When the Europeans would sail back home with symptoms of Beriberi, people would naturally suspect that they had brought some exotic, tropical disease back with them. It was Eijkman who offered the insight that Beriberi was caused by an insufficient diet and not an infection. Eijkman would share a Nobel Prize for medicine with another nutritional hero named Sir Frederick Hopkins who demonstrated through experimentation that  without the yet unidentified “accessory food factors,” proteins, carbohydrates, fats, and minerals could not support normal growth in test animals. Thus our understanding of vitamins was born from chance, scientific observation, chickens, and an Indonesian cook whose name has been lost to history.

Stay curious, stay classy, and never stop learning my friends 🙂

Me Talk Pretty – Hypnic Jerk

Soul-Train-Dancers2_Soul-Tr

One day I will grow the Soul Train afro of my dreams.

Pre-season’s greetings my fellow information seekers! No no, I’ve missed you more. We’re shining this week’s E-Hollywood spotlight on the “hypnic jerk”. While it may sound like a funky, dance from the 70’s, it describes a far more psychedelic physiological phenomenon. Can you dig it? I knew you could.

When I first heard about the “hypnic jerk” I was…

17 years old or so, nodding off in statistics class to that dream where I’m giving my Nobel Prize speech and no one in the audience is laughing at my jokes because I’m not wearing any pants. Anyway, in the dream the floor of the stage suddenly collapsed and I fell into this bottomless pit of my subconscious. At that very moment I was in fact sliding out of my desk. My arms and legs flailed wildly, like a cat trying not to take a bath, knocking my textbooks onto the floor and waking me from my pants-less slumber. What I didn’t know then was that this phenomenon is actually experienced by many people (the falling feeling, not the no pants thing).

Hypnic Jerk

kick2

The Mayo Clinic recommends not taking naps near the Jacuzzi.

In the movie “Inception” (kick-ass movie btw) they refer to it as “the kick,” that moment while asleep when the sudden sensation of falling jolts you awake. Most of us have experienced this at some point and the feeling is anything but pleasant. What I experienced that day in high school was actually a rare scenario of dream incorporation.

The funny thing about R.E.M. is…

You may not know this but during the surprisingly brief stage of R.E.M sleep, where all of our dreaming takes place, your body is temporarily paralyzed. It’s quite normal, and when you think about it, evolutionarily advantageous not to be able to act out your dreams. Otherwise, we would be jumping out the window every time we’re chased by zombie hordes in our sleep. In fact the only motor function that doesn’t seem to be impaired during this stage of sleep is our eye movement. This is how the R.E.M. stage or rapid eye movement gets its name.

Of course, the line separating the dream state from the waking state is notoriously blurry and it is proposed that the hypnic jerk phenomenon occurs during that awkward intermediate stage where the region of our (brain beneath the cortex) most active when we are awake intrudes on our sleepy-time region of the brain (ventrolateral preoptic nucleus, or VLPO) that manipulates our sleep. I will affectionately refer to this region of the brain as “Vilpo” that’s right,…Vilpo Baggins.

Stay with me this gets interesting…

The VLPO region of the brain is practically next door neighbors with the optic nerve (anterior of the hypothalamus). Why so close? The theory is that during the day Vilpo is busy collecting information from our eyes about light levels (time of day) and it uses this solar sense of time to direct our sleep cycle. Yeah..sounds good, but more importantly it is neurotransmitters like serotonin and adenosine that activate the VLPO. These crafty neurotransmitters accumulate throughout the day until they reach a concentration that causes us to turn in for the night. While we sleep the VLPO releases it’s own neurotransmitters that inhibit the neurons that are most active and frisky when we’re awake so that we can stop being so frisky and get some rest. So neurotransmitters encourage sleep and neurotransmitters keep us asleep.

Sleep is not passive. To sleep and to wake means that there is always some element that must actively be kept under control. 

While we are awake the VLPO is inhibited by opposing neurotransmitters. When we are awake our reticular activating system, R.A.S is awake. This region of the brain is BFF’s with the cortex, hypothalamus, and cerebellum which control basically every conscious and semi-conscious thing we do (walking, eating, SEX, etc.). So one cluster of neurons inhibits another cluster of neurons in a daily battle of sleep and wakefulness where both sides win and both sides lose.

So here’s the deal…

Hypnic jerks seem to occur as a kind of involuntary hiccup of motor control during the crossing over phase into sleep paralysis. The mechanism behind this is still poorly understood but it is the last gasp of waking motor function. It is a paradoxical, involuntary muscle reflex (Myoclonus) and it is pretty common in healthy people. We do know that these episodes can be triggered by persistent stress and anxiety, which is never good. It is also indicated that strenuous activity throughout the day can trigger an episode. It may sound paradoxical but you can actually be “too tired” to get a good night’s sleep and you can cheat your body out of its natural progression into the stages of sleep by being either too exhausted or too wired before you cut out the lights.

Let’s say you let 6 hours of YouTube videos play on your laptop while you typed up a research paper, opened 20 website browsers, and then shut your computer without shutting anything down. It may sound like a lousy way to treat your computer but we do it to our brains all the time…we don’t “go to bed” we just slam our laptops shut without “shutting down” first.

Hypnic Jerks seem to serve as a haunting reminder of the gaps in our understanding of the mechanism of sleep.

Human beings make straight lines and sharp angles. Our buildings have perfect triangles, solid walls, and mathematically proportional rectangles and squares. We believe in boundary lines and cut off points but the human brain itself, with its mosaic of soft tissue and blood vessels, is not confined by the same boundaries. You have to consider that perhaps no one portion of the brain is designated strictly to sleeping or waking but that these two states of consciousness are far more intimately connected, perhaps even dependent on each other. The phenomenon of sleep could be nothing less than an infinitely complex culmination of subtle details and relationships within the vast landscape of the brain.

Stay curious, stay classy, and never stop learning my friends 🙂

Secret Life of Yawns

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9 out of 10 Beagles prefer French roast

I have to be honest with you my friends, after many hours of extensive research (2 whole hours) I just can’t wrap my head around this topic. I’ve flipped through page after page of neurophysiology, human anatomy & physiology, and re-runs of Bill Nye the Science Guy. All the while this topic mocks me from across the room, laughing and pointing at me while I stand vulnerable with my intellectual fly open. Yes my friends, the question of why we yawn is quite the physiological puzzler. So allow me to share what I’ve learned so far.

PANDICULATION! (get your minds out of the gutter…I was here first)

Pandiculation refers to the act of yawning and stretching at the same time. It’s that moment we’ve all witnessed when a dog first wakes from his nap. They’ll stretch out onto their paws in that awkward straddle that always reminds me of yoga on stilts. They then open their jaws impossibly wide and yawn. We may not be as cute as our fury friends when we do this but all the tell tale signs are there. Also, have you ever noticed how unsatisfying a yawn without stretching is? In fact, it is suggested that this is one of the main advantages of this activity. What other involuntary responses to stress, fatigue, and boredom do you know of that simultaneously stretch your jaw, tongue, throat, and eardrums aside from dry heaving?

So what does yawning do for us?

Here’s where the theories rear their ugly, wishy-washy heads. As you know, it has always been my mission to give you the facts – raw, unfiltered, with no artificial fillers or sweeteners, but surprisingly, there are more theories on this subject than Rihanna has hairstyles. So here are my top 3 favorite explanations:

Theory #1 – Increased CO2

This charming little theory has been circulating like an urban legend for eons. It suggests that yawning is triggered by a shift in the concentration of CO2 in the blood. Remember that breathing is a kind of constant exchange of oxygen for CO2 and it is just as vital to rid the body of the CO2 generated during the daily metabolism of our cells as it is to take in oxygen. So the idea that the sudden and deep inhalation of air taken in during a yawn is the body’s way of self-regulating for these shifts makes perfect sense to me.

Upon experimental investigation with test subjects however, increasing oxygen and reducing CO2 seemed to have no measurable effect on the incidences of yawning. Sorry CO2, you can take away our polar caps but not our right to yawn.

Theory #2 – Brain Temperature

This theory suggests that yawning is a means of cooling off the brain. As a fan of Sci-fi I dig this explanation because I like to imagine the brain overheating like a high-tech super computer developed in a secret government lab. So in order to keep our test tube, android bodies from nuclear meltdown we have to yawn occasionally.

So it’s not more oxygen that our yawns are bringing in but cooler air to lower our body temperature. When you think about it, the hypothalamus of the brain regulates body temperature anyway. Yawning could just be a sign that our internal thermostat is kicking in. Since body temperature fluctuates with our sleep cycles, it is believed that cooling off the brain heightens alertness and mental efficiency. In fact Alertness ties in beautifully with our third and final explanation….

Theory #3 – Alertness

This is my favorite (my blog defies science and thus picks favorites). This theory argues that yawning is an activity evolved to promote not only alertness but a kind of group vigilance.

fun fact – I yawned approximately 17 times in the process of editing this article.

From the moment we wake our inner clock is ticking, counting down the hours until sleep. As the light changes throughout the day, adenosine (neuron inhibiting, smooth talker that gets your central nervous system into bed) accumulates in our cells like sand at the bottom of an hour glass. Your awareness to stimuli, reaction time, and perception of subtle changes in the environment becomes muffled and muddy. Staying vigilant is crucial in a prehistoric wilderness of dire wolves and sabertoothes that think of homo sapiens as walking, P.F. Chang appetizers (I like the spring rolls).

earlymanSo there you are, standing guard by the cave with your hairy arms and caveman abs. Having just chowed down on grilled mastodon your eyes start to droop. Your respiration shallows and your body temperature fluctuates, but just then, you hear bushes rattle in the distance. The sudden sound makes your shoulders jump (known as a hypnic jerk), jolting you back into consciousness. You smell the distinct musk of a predator dangerously close by. Reaching for your flint tipped spear you start to…yawn? The other members of your tribe also reach for their weapons. Women gather up the little ones and they too begin to yawn (a phenomenon of contagious yawning observed primarily among relatives and close friends rather than strangers). The yawning stretches the jaw, tongue, eardrums, and throat. Arterial blood flow is increased, allowing the brain to cool, prompting arousal just in time to perceive the threat of wolves approaching…or so the theory goes.

Stay curious, stay classy, and never stop learning my friends 🙂