November 14, 2014

The Sweetest Thing

We need sweetness. Yeah, you heard me (well you hear me in your head). I’m not here to bore you with another article about why sugar is bad for you. We get it. As an information saturated society we know more about nutrition today than any other time in the unabridged history of the human race. Yes, sugar is bad for you BUT we still need to sweeten things from time to time. We have evolved taste buds on our tongues for sweet things. Every culture on the planet, from the bleakest deserts to the darkest rain forests, eats sweets. So when sugar is no longer lead singer on the sweetener stage who do we turn to?

Let’s get artificial!

The term “Artificial sweetener” has always bothered me for some reason. It just makes it seem as though we are lying to our tastebuds but the only lie is in thinking that sugar is the basis of our perception of sweetness. Sweetness is in the brain. To understand sweetness think about locksmiths. Yes, every lock needs the right key to open it. A chemical doesn’t have to be table sugar ( C₁₂H₂₂O_{11 )}to have the right molecular structure to unlock our taste buds.

Taste buds, making flavors known for more than 165 million years

A word or two about taste receptors…

The many protruding papillae structures on the surface of our tongue contain receptors that constitute our infamous taste buds. All of these protrusions create a massive amount of surface area around the tongue, providing many points of contact for the foods entering our mouths to make their flavors known. These taste bud receptors have a direct line to the gustatory (feeding related) areas of the brain where we interpret and experience those tastes. Just like sight and smell, taste is largely in the brain. This is why the smell or taste of fresh baked cookies or whatever can conjure up vivid memories of a time and place (rolls from the oven make me think of Grandma’s house).

Humans have big ole brains and those brains are powered by calories. Yes it takes calories to power the brain (roughly 20% of our total intake at rest) just like any other organ in the body. Sweet things tend to have a lot of calories. So it would make a lot of sense that, calorically speaking, sweet things would be so appealing (I see you over there cinnamon roll. How you doing?) What if the pleasure we get from two scoops of ice cream is really a deeply rooted feeling of security that we’ve met our body’s caloric demands?

Saccharin how do you do it?

C₇H₅NO₃S or Miss Jackson if you’re nasty…

When I say “artificial sweetener” do you think of little, bright pink packets? It’s ok, we all do. Saccharin (commercially known as Sweet n Low) has been cluttering breakfast tables like confetti for decades but has been in use for more than a century. Of course saccharin meets and greets the same taste receptors on our tongue as table sugar but it’s 300x sweeter per serving. Where does it get its mutant flavor powers?It’s not fully understood but part of the answer is solubility my friends.

In order for us to taste anything, some portion of that substance needs to dissolve in water so that a sample of it’s molecules can shake hands (on the molecular level) with our taste buds. Saccharin in the form of a salt (sodium saccharin) dissolves in water like a champion and thanks to it’s shape, the molecule has a high affinity for the taste receptors on the tongue. I mean where sugar shakes hands with our taste buds saccharin goes in for the long, awkward hug.

Yeah…Saccharin is “that guy.”

BUT…. is it safe?

You just had to ask that question didn’t you? To be honest (always) the topic of saccharin toxicity is a murky one. It has been investigated more than some organized crime bosses. There are definitely concerns about sodium saccharin’s toxicity. In some laboratory trials high doses of saccharin have been linked to bladder cancer in test rats. Now please keep in mind that they were testing lab rats and not humans. We are yet to find definitive proof that saccharin causes cancer in humans. It was for this reason that saccharin was removed from the U.S. National Toxicity Program’s Report on Carcinogens in 2000 where it had been listed since 1981. Also, the rats in those studies received high concentrations of sodium saccharin. They weren’t casually sipping Crystal Light after working in a few laps on the hamster wheel. For the sake of a toxicity study researchers are looking for toxic effects. So they test and test and test until they find some. A researcher measures those effects at different concentrations under a variety of conditions. In contrast, the amount of saccharin in your packet of sweetener was only intended to make that cup of old, burned coffee easier to drink while you wait for your car at the Jiffy Lube.

So no, I’m not here to defend the little pink packets (though I will accept cash or personal checks if they would like me to.) You will simply have to use your own judgement. However, I will leave you with this thought…

Can a substance that contains no calories or nutritional value still be considered food, and if not, why are we putting it in our mouths?

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

August 17, 2014

Crash Course – Epidemiology

this is how I feel when someone coughs without covering their mouth

Alright party people, let’s get right down to it. The Ebola outbreak is on everyone’s mind right now and I felt obligated as your friend and favorite science blogger (let me have my dream) to clear up a few key concepts that get tossed out by the media like candy wrappers. Epidemiologists (scientists who study disease) have their own technical lingo when it comes to disease and GOSH DARNIT I want you to know it too. Hey, look at me…I care.

The terms of the trade…

Agent – the thing that causes the disease, or put another way, the element that is always present with the onset of the disease and whose presence is essential for the disease to occur.

Reservoir – the habitat where the infectious agent lives and thrives. This can be a stagnant, jungle pond or the intestinal tract of a human being

Carrier – person or critter (bat, monkey, bird) that can harbor the infectious agent and is capable of giving it to others. The carrier often lacks any signs or symptoms of having the disease.

Host – Any living thing that can be infected by a disease causing agent under normal conditions. If it’s a brisk November morning and you’re reading “Horton Hears a Who” to a small room of kindergartners on the carpet and half of them have the sniffles, then you are the perfect host for the Rhinovirus (cold). All the conditions are perfect.

Vector – living intermediary between a reservoir and a host. Mosquitoes are classic vectors, especially since they’ll suck blood from a variety of victims. They are equal opportunity pains in the butt.

Transmission – the mode or mechanism by which the disease causing agent is spread (air, water, food, person to person contact, contact with object)

Virulence – refers to the infectious agent’s ability to cause disease. I think of it as a measure of potency. On the other hand, infectivity describes that pathogen’s ability to spread disease to other hosts. When Chicken Pox shows up at a party it doesn’t just stand in the corner by itself. It turns the music up, heads to the center of the floor, and tries to dance with everybody.

Zoonoses – infectious diseases that are transmissible from animals to humans.
It’s funny just how foreign this term is for many of us, since there are so many devastating diseases to the human population (Avian flu, Swine Flu, Black Plague, Rabies, Lyme’s) that we acquire from other species.

Morbidity – is essentially an assessment of just how sick the disease in question makes you. It also has a statistical value representing the relative occurrence of disease in a population.
The definition of morbidity has a wonderfully legal sound to it, but the further a disease moves you away from your normal, healthy physical or mental state the higher the morbidity of that disease is. It is the degree of transformation your body goes through in the course of a disease.

Let’s put it all together…

Gina flew in yesterday from Boston on a late flight back to Georgia. The 5 year old behind her showed her all of his limited edition Shrek action figures on the ride back. One of them was sticky from the gummy worms he’d eaten earlier. She’d gotten back at 10pm but her college peeps were in town and the beers at Karma Mike’s Grill were still half priced until midnight. Work came way too early that next day. She only slept 3 hours and the AC in her office was at full blast.
By noon the sneezes started and her nose would not stop running. Around 2:30 all the name brand, instant coffee in the world could not keep her eyes open to read through all her emails. Later that night her throat felt scratchy and her muscles ached as if she’d lost a cage match. That’s when she remembered the kid on the plane and the suspiciously sticky Shrek. Suddenly Gina understood everything that was happening to her.

Our Cast…

Gina – Host

5 year old – Asymptomatic carrier

Shrek action figure – mode of indirect transmission

Respiratory tract – reservoir of virus

Rhinovirus – infectious agent

I hope this helps. Stay curious, stay classy, and never stop learning my friends 🙂

June 2, 2014

Malaria II – Full Circle

Hello party people! So we’re back to finish up our chat about malaria. Last week I took you behind the scenes with the curious parasite (Plasmodium falciparum) that causes malaria, and its obnoxious insect carrier, with the face for radio, the Anopheles mosquito. Today I want to focus on the disease itself. Sure, having a parasite that rapidly divides in the liver and spreads through the blood stream clearly doesn’t sound as fun as dinner and a movie but how exactly does our body respond to these microscopic freeloaders?

Fun fact – Mosquitos do not depend on blood as their primary food
source. Most of the time they eat like vegan, yoga instructors,
feeding on sap and flower nectar for carbohydrate fuel to power their
airborne lifestyle. Blood becomes a necessary source of protein for
developing eggs. So it is actually the female Anopheles that goes buzz
in the night.

Act I – Incubation stage

I don’t know about you, but if I just moved into a new apartment I need a few days to get settled in, unpack some boxes, and tape my Marley posters to the wall before I throw a party. Plasmodium falciparum is no different. At this point the Plasmodium is still hanging out in the liver cells. It can take up to 30 days after the
initial infection before the first symptoms appear, and those range in severity.

Act II – Blood stage

a closer look at the hemoglobin protein. P. falciparum converts the heme subunit to hemozoin.

The chaos ensues once the Plasmodium disperses from the liver and begins circulating in the blood stream. It’s the hemoglobin protein in our blood that they’re after. I don’t want to wander too deep into biochemistry, but if you recall from my earlier article on blood, each hemoglobin protein contains a vital compartment called a heme group. This contains a tiny molecule of iron at its core. This is what binds

the oxygen in our blood. Heme is also toxic when it is released from the hemoglobin. To get around this toxicity the Plasmodium can store heme molecules in their single-celled body in an insoluble, crystallized form called hemozoin. Inevitably the red cells lyse,
releasing the plasmodium along with all the waste products leftover from their hemoglobin feeding frenzy, to include hemozoin. This becomes bad news for us.

When it comes to our immune system our blood stream is a small town
and our white cells hate strangers with a passion. Eventually,
wandering T-cells with the right receptors will encounter Plasmodium
merozoites in the bloodstream (by detecting dsDNA on their membrane
surface) which triggers the release of pro-inflammatory cytokines. However the hemozoin that is released when the red cell ruptures seems to trigger an immune response on its own.

Unfortunately, our immune response is not always strong enough to
completely clear the infection. This is partly due to the many changes
the plasmodium goes through in its life cycle that allows it to dodge
the immune response. It goes through 7 stages, altering its
biochemistry a little each time.

One of the classic presentations of this disease is intermittent
fevers. Typically when your fever stops you start to feel better, but
with a malarial infection fevers often occur in waves every 48-72
hours. This is the result of the rupturing of blood cells as the
parasites continue to multiply and invade new cells.

Signs and Symptoms

That’s right, I know what you really really want…

Think back to the last time you or someone you’re close to had the
flu. When you get hit with the flu you typically look awful, drunk, and exhausted like you haven’t slept since the Spice Girls were last on tour. During classic cases of P. falciparum infections, patients will present with “flu-like” symptoms of high, persistent fever, headaches, chills, sweats, anemia, and vomiting. Remember that during the blood stage of the infection blood cells are being destroyed. So the patient is weak and essentially poorly oxygenated. It is basically a parasite-linked anemia.

Malaria can become deadly if left untreated when infected cells begin to clock capillaries of the brain (cerebral malaria). This can ultimately lead to brain damage, coma, or death.

Testing Methods

We can identify malaria directly from a peripheral blood smear where a
giemsa stain is added to a drop of infected blood on a glass slide and
examined under the microscope. This kind of testing is wonderfully
direct. The problem with poorly developed countries is that proper
testing facilities, microscopic equipment, and trained professionals
who know what to look for are in short supply. So there are RDT’s
(rapid diagnostic tests) available that can identify specific malarial
antigens in patient blood samples. Much like a Strep or flu test, the
patient’s sample is combined with a reagent in a tube or cassette
where a qualitative reaction (positive or negative) can be observed.
However, depending on the concentration of Plasmodium in the blood a
patient may have a false negative. So there is still a need for
confirmatory testing, especially in areas of the world (I’m looking at
you Africa) where drug resistant cases are high.

Treatment

Good Ole Chloroquine…

So we know the plasmodium needs to break down the hemoglobin in order to use those lip-smacking amino-acids while not poisoning themselves with the heme that gets released. So they form hemozoin crystals of the heme to disarm its toxicity.
Welcome to the wonderfully clever world of chloroquine. This drug diffuses into the Plasmodium, halting their ability to form hemozoin crystals. This allows the heme to build up in their nasty little bodies, shutting down their metabolism. Sadly, chloroquine resistant malaria is common place in malarial hot zones. In these cases patients require drug combinations like quinine sulfate and tetracycline.

You also have to manage the mosquito side of the disease. Spraying for mosquitos to control the population has been effective in many urban settings. We also have to understand the behavior of the mosquito. Anopheles prefers to feed at night until the wee hours of the morning. So distributing sleeping nets in malarial hot zones can literally save lives.

The CDC has mapped out malarial zones around the globe. So travelers are encouraged to seek malarial prophylaxis to prevent infections.

Here’s the bad news you already know..

– Children are the most at risk from malaria. In fact it kills more children globally than anything else.

– Diseases thrive in areas where the population is dense and the
availability of adequate healthcare is scarce. This creates a scenario
where the mosquitos are more likely to bite infected individuals. An
infected population left untreated inevitably leads to a more
resistant disease.

Luckily we don’t live in a vacuum and we can contribute. There are a number of organizations out there committed to finding solutions for this global problem. Here’s one organization I happen to like (no, I’m not affiliated with them)

http://www.malarianomore.org/pages/the-challenge

Hopefully I cleared a few things up about this topic. If you have questions please leave me a comment.

As always, stay curious, stay classy, and never stop learning my friends 🙂

February 17, 2014

Fun Facts – A Touch of Gray

Oh yes, it WILL happen to you. Don’t worry it happens to all of us, aging that is. More specifically, gray hairs happen. That’s right our bodies, unlike diamonds, aren’t forever. Hair follicles lose their pigment as we age. There is a family of pigments in our bodies called melanins that contribute to hair and skin coloration. So whether your complexion is Godiva, chocolate brown like Djimon Hounsou, salted caramel like Rosario Dawson (call me), or slow churned vanilla like Olivia Wilde, you have melanin to thank. Oh man, all this talk about race makes me want ice cream.

Anyway…

Hair is like sea coral. Yes, that’s random…try to focus. Much of the underlying structure of a coral is the deposited, calcium carbonate remains of dead cells that harden and accumulate while new cells grow over top of the layers. The structural anatomy of a hair follicle is actually curiously complex but the portion of that follicle that we see protruding from the skin (the hair shaft) is just the deposited remains of dead keratinocytes (keratin containing cells). However, unlike coral, the living cells are underneath. Keratin is the crazy strong protein that gives hair, nails, and skin their structure and durability. That same protein that allows Scarlett Johansson’s golden locks to flutter in the wind are what make a rhino’s horns hard enough to dent the door of a Jeep when the tourists get too close.

Clusters of rapidly dividing keratinocytes at the root of the follicle team up to produce keratin. Cell division and keratin production creates a dense mass of material that builds from the bottom up. Meanwhile, bordering those feisty root cells are melanocytes that pass their melanin granules to the keratin producing cells. So even as the cells die they retain whatever color was passed on.

As we age melanocytes become less active and die off and so more and more hair shafts reach the surface without pigment. So just to be clear, your body doesn’t produce gray hairs. It simply stops producing melanin pigment within the hair follicles. The resulting hair strand is actually colorless.

Now the rate at which our hair loses its color is largely genetic. In know, genetics seem to be the new cop-out answer. It’s like when they use “instinct” to explain why ducks fly south for the winter. However, this time we have to point the finger at inheritance for our sexy, silver sheen.

Stay classy, stay curious, and never stop learning my friends :-)

January 11, 2014

That Dizziness Thing

After two pink bags of cotton candy all the rides were a little blurry that day.

Ok brace yourself, because I’m about to make a painfully obvious statement. Sometimes what we say we’re feeling and what we are actually feeling is not the same thing. Yes, you do it too. Oh yes you do! Do I need to call your mom and let her know your pants are on fire? Listen, I don’t want to fight about this, but I will say that there are a handful of terms good people like you and I use to tell our doctors what we’re feeling because we don’t know any better. For example, when was the last time you felt dizzy? Perhaps I should say lightheaded, or that you felt like you were going to faint (presyncope). Maybe you felt like the room was spinning (vertigo).

We use “Dizzy” to describe all of these sensations when in fact sometimes we’re only experiencing one of them. When the teenager behind the counter at the ice cream shop takes your order you don’t say “give me two scoops of the really cold kind” do you? Sometimes names matter. Well get ready, because we’re about to get technical.

Hey Buddy, maybe you should sit down. You look like you need a juice box.

Light headedness is typically the result of a sudden drop in blood pressure (hypotension). Our bodies are a lot like one of those giant, dancing balloon characters outside of a used auto dealership. You cut off the fan (the air flow) and the balloon man falls to the ground. Well when our fan shuts off (our blood flow to the head is restricted) we faint. We refer to this as “syncope.” That feeling that we are about to faint is “presyncope.” We can also experience the lightheaded blues when we stand up too fast and we refer to this as “orthostatic hypotension,” where the blood flow is affected by the positioning of the body. Ok blah blah…that’s all very interesting (yawn), but I want to get to the good part, vertigo.

Vertigo is CRAZY interesting. Actually, for the rest of this article I’m just going to talk about vertigo. Everything else is dead to me.

Vertigo is a profound sensation of disorientation. You can have the feeling that the room is spinning or that you are spinning. You can also experience the sensation of falling or that the ground or room is tilting. All of these trippy sensations can make you feel incredibly off balance and often lead to nausea.

All of these sensations are caused by a malfunction (minor or severe) in the way your brain is receiving information from the balance organs of the body. What kind of malfunctions you ask? Well if the possible causes of vertigo were a dusty road in New Mexico that split in two, one road sign would read “sensory neural pathway” and the other would read “organs of the inner ear.” Need more? As the comedian Bernie Mac used to say, “Let me break it down for you like a fraction.”

Your brain talks to your body constantly. Like an overprotective mother the brain asks your eyes “where are you? What are you doing right now? What do you see?” However, Mother is just looking out for us, taking that visual input and coordinating our skeletal muscles/motor control to maintain an upright posture and orient the fluid within our inner ear like the bubble in a carpenter’s level (see fig. 2) so that we have an accurate perception of up and down, left and right, backwards and forwards. That intimate communication between brain, eyes, and motor control is referred to as the vestibulo-ocular reflex. Go ahead and click this link

https://forgottenphysiology.com/2013/12/19/me-talk-pretty-vestibulo-ocular-reflex/

it won’t bite 🙂

Balance is in your ears?

This balancing act is brought to you by our inner ear. The physical interaction of sound waves within the intricate, spiraled canal of bone called the cochlea in conjunction with the stimulation of auditory nerves are largely responsible for how we hear sound. However, one of the more mystifying tricks our inner ear can perform is that of our perception of balance. Alright, we need to zoom in on this thing. Look down there…

ok keep your eyes on the swirlie, looping purple thing (labyrinth of the inner ear) in the diagram. This is where the magic happens.

No no, I mean closer than that…

Welcome to the Labyrinth of the inner Ear

A special thanks to Thing for demonstrating the Carpenter’s level

This structure has more twists and turns than a back road in Lexington, Virginia so I’m only focusing on two main parts for now, the semicircular canal and the otoliths. That reminds me, how familiar are you with building houses? That’s ok, just look to the right of the screen. See that’s a carpenter’s level. Builders set it on top of fence posts, center blocks, steel support beams and anything else they need to have level with the ground. That bubble in the center tells them how far off they are. Inside each ear are three very similar structures, semicircular canals, made from bone and tissue that your brain communicates with to maintain rotational balance and orientation (like when you’re busy doing back flips like Night Crawler from X-men). These are tiny, fluid filled canals that loop parallel and perpendicular to each other. That itty bitty amount of fluid inside pushes on the hairs of a structure called a cupula that translates that mechanical movement of the fluid into an electrical message that tells the brain something like “hey, this guy’s doing a cartwheel.” You have three of these in each ear; anterior, posterior, and horizontal that correspond to vertical, horizontal, and diagonal rotations of the body.

The more you learn about the structures of the inner ear the more this all begins to sound like some freaky game of pinball, but we’re not done. The otolithic organs allow us to sense linear acceleration by aid of tiny crystals suspended in viscous fluid [I always thought the term viscous was kind of creepy, but that’s just me]. We have two otolithic organs on each side; the urticle, and the saccule. The urticle is tuned-in to horizontal movement and the saccule is all about the verticle changes in position.

The otolith organ is this crazy looking sac of fluid with a cluster of sensitive hairs. The fluid as I mentioned before is thick, viscous and contains a lot of tiny calcium carbonate crystals that make it grainy as well. So when the head moves this nasty substance produces friction against the hairs and that inertia is translated into vertical and horizontal linear movement by the brain.

Back to Vertigo

When you are suffering from vertigo disruption of the balance organs (especially those of the inner ear) and the sensory neural pathways that talk to those organs are typically suspected. Benign paroxysmal positional vertigo (BPPV) is common when there is inflammation from infections or injections. If inflammation is significant enough it can disrupt the movement of otolith crystals within the inner ear, sending mixed signals to the brain. That can definitely make you feel like you went too many seconds on the mechanical bull in Salt Lake City.

Brother, what a night it really was…

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

November 25, 2013

Hiccups – the Devil’s plaything

Is that the same devil you had in mind? Twins!!

There’s public radio telethon week, toll roads, vending machines that give you Diet Pepsi when you clearly pushed the “Coke” button, and near the top of the list are hiccups. These are a few of my least favorite things. Oh, you know this guy loves the human body. There are few marvels in this world more elegant, more profoundly complex than the body and it’s nuts and bolts, but son of a [CENSORED], hiccups are the devil! I seriously doubt that a successful pick up line has ever been delivered while battling with the hiccups. Hiccups lie in wait like mean-spirited hecklers waiting to kill the mood of your acceptance speech or interrupt the punch line of your best dirty joke. So in this episode of Forgotten physiology we’ll pose the question; Hiccups, what’s your deal?

Yes, I prefer to think of my hiccups as the old men from the muppet show
http://www.youtube.com/watch?v=PGfx3QAV64M

Synchronous Diaphragmatic Flutter (or Miss Jackson if you’re nasty)

Mechanically speaking, hiccups are nothing more than spasms of the diaphragm; short, involuntary contractions forcing air through the windpipe that is then immediately closed off by the tough, elastic flap of the epiglottis. This closes off the vocal chords like a trap door that says “No more air for you! No!” and produces that signature, sexy frog sound of a classic hiccup.

The phrenic nerves begin in the cervical vertebrate (C3-C5) and zip line down between the heart and lungs to connect with the diaphragm.

You have a left and right phrenic nerve that connect to the diaphragm to control its contractions and receive sensory input in return. “Sensory input?” Well sure, you don’t just blindly send out messages. You look for a response. Your nervous system is all touchy feely and needs to be able to sense where everything is…no organ left behind. Those nerves are the only electrical wiring operating the movement of the diaphragm. So any significant disruption or irritation of the phrenic nerves can cause spasms and ultimately hiccups. For example, if you just had a bad breakup and decided to go Tazmanian Devil on 2 large orders of pork fried rice from Wong’s Wok, a full or distended stomach can press on the phrenic nerves and trigger hiccups.

But who is really in control?

We may not think about it but the diaphragm is made of “skeletal” muscle. If you remember our chat from muscle mania, skeletal muscle is under the control of the somatic nervous system. This typically means that it is under our control. We can, for example, contract our diaphragm muscles ourselves and draw in a deep breath. However, we don’t exactly tell our diaphragms to spasm do we? Ahh…here’s where it gets interesting.

A thought experiment..

You and your body are one and the same right? I mean you don’t feel separate from your body do you? If I ask you to pass the mashed potatoes you don’t ask your hand to grab the bowl. Your brain and your hand flow together, without interruption.
Now think about a hiccup. Does that ever feel like something YOU did? No way, the hiccups happen as reflex and your brain gets the feedback. These are controlled by a “reflex arc,” neural pathways (composed networks of neuron cells) that connect to the spinal chord BEFORE reaching the brain. Some neural pathways have a long way to go to reach the brain, your central command center. The spinal chord works like an intermediary traffic control center, managing the local stuff and all the sensory input from the extremities. This allows motor reflexes to occur instantaneously without checking in at the office (brain) first. Your brain isn’t left out of the loop. The motor neurons of the spinal chord are simply the first to respond.

But why me? Why?!!!

Typically when we get the hiccups we were eating too much or eating too fast, drinking too fast, or hitting the sauce a little heavy (either alcohol or carbonated beverages). Episodes can also be brought on by excitement. I’ve always said that too much happiness is dangerous. These hiccups don’t last long and typically resolve on their own without tongue pulling or drinking water upside down.

There are of course persistent hiccups that are linked to an encyclopedia worth of clinical problems ranging from stress to heart issues to neurologic and metabolic disorders. So if 48 hours have gone by and you’ve still got the chirps then it’s probably a good time to see your doctor my friend.

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

Posted in Nuts and Bolts
Tagged biology, health, physiology, science
2 Comments

November 4, 2013

Baby, it’s cold outside!

you know that hat is very slimming

Here’s the truth of it. Mother Earth, the blue planet, our very own 3rd rock from the sun is perfect for us. By that I mean this planet has more than enough places (from Bangkok to New Jersey) that are both warm and cool enough for us to survive and thrive as a species. Our solar system is a rough neighborhood. Even on the surface of the moon there is at least a 450° F difference between standing in the light and the shade. So believe me brothers and sisters when I say that it is truly remarkable that we get to hitch a ride on this cosmic trolley called Earth.

Asashoryu is not impressed by your skinny jeans.

The human body has special needs. Our metabolism functions optimally within a narrow, warm fuzzy range between 36.5° C and 37.5° C (98-100° F). Most of us don’t climb much further than 98.6° F (hyperthermia) unless we’ve caught a nasty flu virus or overslept on a tanning bed. Now that is one tight range for homeostasis to be maintained. I’m talking tighter than a sumo wrestler in skinny jeans. This is the range where our enzymes can function optimally, where our cells can use energy stored in glucose, where blood can adequately deliver oxygen in exchange for carbon dioxide, and an [EXPLETIVE] load of other vital, biochemical gymnastics.

“Hypothermia” – is not an 80’s Hair Band

Medically speaking, hypothermia is the state at which your core body temperature drops below 35° C (95.0° F) but I’m willing to bet that for your core temperature to slide down even 3 degrees you’re already feeling pretty cold and have been for some time. If you put the lid on a warm cup of coffee and set it in the freezer you’d be lucky to find iced coffee waiting for you even a half hour later. The human body has water tight skin, fat tissue, body cavities, and many times the volume of a 16 oz cup of Joe. So when we get cold it’s the real thing and our body fights for us right up to the very end.

A word or two about Vasoconstriction

Consider that the blood flowing through our veins carries heat. So when we start to lose heat the blood becomes a kind of heat currency that the body gets mighty stingy with. So when the air gets frosty the blood will begin to move away from the small, surface vessels in the skin and concentrate its energy on the brain and other vital organs. The skin is also what is exposed to the cold air and where 90% of body’s heat is lost.

The Shiver

When it comes to survival by any means necessary my team captain will always be the hypothalamus. We actually have a shivering center of the brain located in the posterior hypothalamus, which is normally kept in check by the anterior portion of the hypothalamus. However, when the body’s core temperature drops just below it’s warm fuzzy range your posterior hypothalamus kicks in and says “everybody dance!” This leads to the short, rhythmic muscle contractions in an effort to generate heat.

So what happens when the big chill hits?

Stage 1 (mild – “Time to put the snow balls down and come inside”)

This occurs after a 1-2° drop in normal body temperature. Shivering, hypertension, tachycardia (heart rate over 100 rate/minute), and vasoconstriction (contriction of blood flow through vessels). Clinical cases vary in which hyperglycemia or hypoglycemia (high and low blood sugar) have occurred. The chances are roughly 50/50. As metabolism staggers the cells decrease their uptake of glucose and the tissue’s sensitivity to insulin becomes impaired allowing glucose to spill into the blood. This is a hyperglycemic state. However, having a low blood sugar to begin with (especially if you’ve been wandering around for hours in the cold) can accelerate the onset the onset of hypothermia.

Stage 2 (moderate – “Dude, you don’t look so good”)

Loved that movie 🙂

This is seen after a 2-4° drop from normal. Ok we say moderate but by this point you’re pretty gosh dang cold and have been for some time. The surface vessels of the skin constrict, drawing blood to the vital organs, shivering, coordination, and mental state all worsen. Portions of the body rich in capillaries like fingers, toes, lips, ears (basically all the delicate parts most exposed to the air) all get pale and blue, and not in that sexy, Avatar kind of way.

Stage 3 (severe – “Somebody call an ambulance!”)

At this point the core temperature has dropped below 32° C and your body is pissed. The heart rate drops down to the 30s (normal resting heart rate for adults is at least 60 beats per minute), the respiratory rate decreases, the blood pressure drops. It’s like the temperature just turns your volume down. The vital organs are beginning to fail as metabolic functions stagger. Your muscle coordination and mental function are terrible by this point and you’d be lucky if you can unscrew the loose lid on a peanut butter jar or remember the words to “Happy Birthday.” Then something really, really strange tends to happen…

The Deadly Strip Tease

It’s a phenomenon referred to as paradoxical undressing. People at the edge of their sanity, in the most severe stages of hypothermia will begin taking off their clothes. They reach a state where they become hellah-confused, disoriented, and even violently aggressive where they just start shedding layers as if they were burning up. One theory is that by this point the body has been so beaten up that the signaling pathways of your hypothalamus are sending all the wrong messages like an evil cell phone that sends “let’s get back together” texts to all your ex’s. This is also associated with a “hide and die” syndrome (terminal burrowing). Victims are sometimes found curled up in small, hidden spaces. I don’t know physiology fans, perhaps in moments of extreme circumstance human beings simply switch back to our most primal selves.

So because I care here’s an ounce of prevention…

If you’re out in freezing temperatures stay dry (wet skin is a death sentence), wear multiple layers especially synthetic, poly blends that retain heat better then cotton, stay hydrated but avoid cold liquids that will just further lower your core temp, cover your head, and NO no no alcohol! It’s a vasodilator (increases blood flow in the vessels) drawing blood/heat to the extremities and thus away from your core. That rum n coke just isn’t worth it.

As always stay curious, stay classy, and never stop learning my friends 🙂