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 🙂

December 19, 2013

Me talk pretty – Vestibulo-ocular reflex

Hello and welcome to the first segment of “me talk pretty” where I bring you tongue twisting terms from the most remote corners of physiology. This week’s super sexy, fancy-pants physio term is….

“Vestibulo-ocular reflex (VOR)”

This is a highly adapted eye reflex in humans that keeps images fixed or stablized on the retina (in the center of your visual field) by allowing the eyes to move in the opposite direction of head movement like a compass needle that points to magnetic north no matter how much the ship tosses on the waves. Your VOR is incredibly fast (fraction of a second) and it needs to be in order to compensate for even the most subtle head rotation along an axial plane (vertical, horizontal, or diagonal). It is what makes clear vision possible. If you were a catcher for the Yankees and your VOR were a fraction of a second off you would be grabbing for blurry fast balls at 90+ mph, but hey, who wants to live forever? (No one should be grabbing for blurry balls) So the next time you’re trying to read your Vanity Fair magazine on a Chinatown bus with bad suspension, finish a sudoku puzzle on a plane while someone’s devil spawned child is throwing a fit and kicking the back of the seat, or just trying to check out the fit brunette jogging by out of the corner of your eye, remember to thank your VOR for keeping that image nice and clear.

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 🙂

October 29, 2013

Hair Raising

electric razors just don’t give you that clean shave

That’s right brothers and sisters Halloween is one of my favorite Hallmark holidays. The candy, ghost stories, bad zombie makeup, and shapely women in revealing witch costumes all put me in the holiday spirit. I have to admit though, something has been bugging me. There I was, watching cheesy, poorly scripted thriller movies at 1am alone in my creepy old apartment. I’m watching one of those scenes where the woman in a low cut top is searching the basement with a flashlight for strange sounds when I feel the hairs raise on the back of my neck. “Why is that?” I think to myself. No, I know why MY hairs stood up. I’m a total wuss when it comes to ghost thrillers, but why does that physiological response happen to all of us when we get spooked?

cat demonstrating pilomotor response to confrontation while walking the mean streets

Ancient roots

There is something you and your cat have in common that you may not know. Scientist refer to it as the pilomotor response. You may know it better as “goosebumps” when hundreds of tiny bumps raise on your arms and legs. If you’ve ever gotten out of the shower and stepped into the much cooler air outside of your bathroom that’s typically when you’ll notice them. Well cats display this same behavior when they are confronted by another aggressive cat telling him to “step off my turf” or something scarier like a dog or falling metal trash can. The hairs extend as they rise to their toes to appear as big as possible for competition or predators. Well the cool kids (scientists) believe that this phenomenon in human beings served a similar function. Well I don’t know if you’ve noticed, but humans beings today, version 5.0, aren’t nearly as hairy as our fiercer, planet of the apes ancestors.

Well these days goose bumps are a “vestigial” response meaning it has out lived it’s original function. However, this involuntary reaction is still triggered by moments of intense stress and emotion like fear, exhilaration, and you know, moments of intense..um..inspiration (sexual arousal). All of this magic is of course brought to you by our dear friend the sympathetic nervous system, home of the “fight or flight” response.

Let me set the scene…

Let’s say you just walked out of the shower…No wait better yet, let’s say Michelle Rodriguez just walked out of the shower wearing nothing but a towel when suddenly she hears a loud crash from the kitchen…

About 90% of the heat in Michelle’s super fit body is lost first through the skin, even more so when wet, because water transmits heat away far more efficiently than air.

She slowly walks down the stairs….

Respiration increases along with her heart rate as blood flow is conserved for the brain and other vital organs, temporarily halting digestion. A sudden rush of energy is felt as epinephrine acts on the insulin producing liver cells, allocating glucose so that Michelle’s warrior, Resident Evil reflexes can spring into action if need be.

She approaches the doorway of the kitchen, reaching for her limited edition, zombie killing, 9mm Smith & Wesson…

The adrenaline coursing through her blood stream has taken her mind off the chill in the air but her body is still losing heat through evaporative cooling of the skin and through the rapid breaths (lungs accounting for 10% of total heat loss).

She turns the corner..

Tiny, arrector pili muscles located at the base of the hairs on her neck, arms, and perfectly toned legs contract forming goose bumps and raising the hairs on Michelle – as both a response to fear and her body’s attempt to conserve heat.

She puts the safety back on her pistol, realizing that it was just her silly cat knocking over a bowl of Captain Crunch. That’s when it dawns on her “I only buy Raisin Bran!”

Happy Halloween my friends and as always…stay curious, stay classy, and never stop learning 🙂

“André tells the best stories”

October 26, 2013

Cell Talk

Hello again fellow information addicts. Did you have a good week? Well mine was just bursting with fruit flavor (try not to look too far into that). Anyway, after our last chat about the role of our immune system in allergic response, Allergies Oh My, I felt this incredible need…I mean like a deep and real need to talk about another wild topic in immunology, communication, as in cell to cell communication. Believe it or not, our white cells are quite chatty with one another. They don’t talk about reality shows, how Sarah’s new hair style is “all wrong for her” or what horse they’re betting on at the track in Charleston this payday weekend. It’s a non-verbal communication (can I say body language without it being a pun?). No, when our cells talk to each other they only want to know one thing, “are you one of us?” That is the very definition of immunity, being able to distinguish the sharks from the minnows, what scientist refer to as “self from non-self.” Cells accomplish this without secret handshakes or gang colors. Instead, each cell comes equipped with a special membrane bound receptor that displays protein epitopes, portions of particular proteins that cell in question makes.

So the white cells are like Penn State campus security, floating around, approaching sketchy looking cells it hasn’t seen on campus before going “alright kid, let’s see some ID. What’s your major? Ok ok…looks good, move along.” Every nucleated cell comes equipped with a membrane bound receptor, a complex of proteins referred to as a Major Histocompatibility complex, or MHC. These receptors operate by aide of two major biochemical pathways, MHC I and MHC II. I think of them as having different versions of software. In fact, the nature of these receptors is profoundly Star Trek-ish and sophisticated. Here’s the situation…

See that orange socket wrench poking out of the cell? That’s the kind of receptor we’re talking about.

Cells have membranes made up of a ballpit of proteins, fats, carbohydrates, and lipids that form this semi-solid layer that keeps their insides from spilling out onto the dance floor. So anything that cell needs to take in must pass through the membrane. This includes information. For a cell, information comes in a molecular form just like everything else that has to be taken into the cell. There’s no high speed internet, no Wi-Fi, no Skype. It’s like having your mail served to you on a dinner plate along with your chicken tenders. So in order to communicate to a cell you would need to A) keep that message painfully simple and B) convert that message into a molecular form that can be readily passed through the membrane. One form of cellular message that white cells use are referred to as cytokines. Cytokines are both released by white cells and taken up by them and they trigger vital immune responses. For example cytokines are responsible for attracting white cells to the site of an infection as well as switching them on and kicking them into action. Let me put it this way, a white cell without cytokines is like a police department with no dispatcher. Now back to receptors.

MHC II pathway

This version is typically found on white cells that act as antigen presenting cells or, as I like to call them “instigators.” These are cells like macrophages, monocytes, and dendritic cells that spend their time gobbling up any weird cell, bacterium, viral particle, or whatever that doesn’t identify itself in a timely fashion or flash the right ID. After the cell has devoured it’s prey and digests it with its cellular stomach (lysozyme/peroxisome) the organic bits and pieces like amino acids, lipids, etc. get recycled and distributed. Some of those bits, epitopes get attached to the MHC II receptor.

I’ll bet you didn’t know your cells were pre-labelled

The cell has numerous receptors in fact and in this case the receptor is inside of the cell in the cytoplasm where all the action is happening. The MHC II/epitope complex makes it’s way up to the membrane surface of that antigen presenting cell for display like an Applebee’s appetizer sampler platter. Well, it’s a bit more morbid than that because remember, this is a sample of the enemy (very Silence of the Lambs). So it’s floating around flashing the ID to other white cells “have you seen this guy before?” until it meets a T-cell (a CD4 cell to be exact) that says “oh yeah, I’ve met this guy and he’s a total D-bag. I’ll let everybody know.” In the case of an adaptive immune response that white cell will seek out a B-cell holding the same epitope, release cytokines to activate that B-cell to produce antibody against the invading microbe.

MHC I pathway

This version is super friggin cool. It’s found in every single nucleated cell in the body. It’s function; display protein epitopes of what what that cell is producing. Yup, it’s like a show and tell receptor for cells. The cells say “look what I made in arts and crafts today.” If it’s something our white cells recognize than everything is gravy. Oh man, but if that white cell doesn’t like what it finds..well all hell kind of breaks loose. There is a no nonsense kind of white cell called a Cytotoxic T-cell, or CD8 killer. When it discovers foreign epitopes on a cell’s MHC I receptor it intiates a kind of self destruct command for that cell called apoptosis. To understand this you need to understand something about viruses. Viruses ONLY survive inside of a host cell…key word “inside.” They don’t just hangout inside the cell and watch sports center. They are up to no good, using the cell’s nuclear machinery and endoplasmic reticulum to produce viral proteins and essentially make new viruses. Once a cell is hijacked and turned into a viral production line there’s no going back. So like the sad scene in a zombie apocalypse film the CD8 takes the poor, infected cell out of it’s misery, which halts the replication of the viral particle. Our immune system evolved in this way because it has witnessed what viruses are capable of and has learned not to hesitate to pull the trigger.

Well my friends I’m off to go make a difference (get Thai food). As always stay curious, stay classy, and never stop learning 🙂

September 28, 2013

Allergies Oh My!

Hello Internet! No, I missed you more. Let’s chat about allergies shall we

Let me set the scene…

It’s a beautiful morning in March. No scratch that, it’s a perfect morning. It’s the kind of day that wakes you up before your alarm clock and you are surprisingly ok with it. You’re even singing in the shower (if I don’t sing in the shower I don’t feel quite as clean). So you kick the door open to get outside and get this day started when it hits you, allergies, Mother Nature’s “you don’t belong here” bitch slap to the senses.

First it’s a sneeze, a harmless little sneeze that triggers 3 more sneezes. Then your nose starts to run in that “get me a Kleenex or I’m wiping it on my sleeves and I don’t care who sees me” kind of way. Of course, the last straw…the absolute take me out back and put me out of my misery moment is when the eyes start their itchy, watery awfulness. So you look around to see if this is happening to anyone else…if anyone is hurt…if there is a special report on channel 6 about bio-terrorism attacks in your neighborhood. No one else seems to be effected and it’s not terrorists or a demon possession. Here’s what happens…

I’m fine! It’s just allergies ok.

The Super Condensed Cliff Notes Version

Allergens in the environment stimulate our B-cells to produce IgE that builds up in our bloodstream eventually attaching to Mast cells and basophils. Upon subsequent exposure, the allergens bind to the membrane bound IgE on the surfaces of the Mast cells and Basophils triggering the release of histamine filled granules, initiating the localized inflammatory response we all love to hate.

Your White cells are angry (localized immune response to allergens)

Alright I’m sorry but I’ve got to review a few things with you people.We learned as kids that our blood is composed of red cells that carry oxygen and white cells that help fight infections. The truth is we have a variety of white cells (leukocytes) that each has its own, nifty G.I. Joe-like skills at combat. Let me draw your attention to 3 cells for now; B-lymphocytes, basophils, and mast cells.
Your B-cells A.K.A B-lymphocytes develop from stem cells in the bone marrow and later hang out in the lymphatic organs (like your lymph nodes) where they are educated in the ways of antigen recognition (sort out the good from the bad) and are armed with the black magic ability to produce antibody for whatever ails you.

If you recall, antigens refer to any substance that can elicit an immune response. Antigens can be composed of carbohydrates, lipids, proteins, or anything that triggers the cascading effects of your immune cells (leukocytes) when they come into contact with it.
Antibodies are highly specialized, fancy-pants proteins produced by B-lymphocytes that have the ability to bind to the antigens of foreign invaders (pathogens) that slip into the bloodstream (Bacteria, viruses, microscopic fungi). The pathogens that invade our bodies display antigenic molecules on their surfaces, which is how they get spotted in the first place. If our B-cells make antibody that fits that antigen molecule (which it pretty much always does) our white cells will begin beating down that pathogen in a large-scale battle royale that involves cell divisions and some serious Pacman-like chomping action.
That’s right, your white cells divide and conquer. That’s why doctors are often expecting your white cell count to be elevated during and infection. They are quite literally forming a clone army.

When they bind to a pathogen it allows white cells like macrophages to engulf them and also facilitates the killing action of another class of bad-ass, ninja protein referred to as complement that are always present in your bloodstream.
Our antibodies come in a variety of shapes, sizes, and classes based on complexity and specificity.
Keep in mind that there is a lot of crap floating around in the air, hanging out on table tops, Bank door knobs, and wherever 4 yr olds are running around, sneezing without covering their mouths.

Best Summer ever!

These microbes are just looking for their 15 minutes of fame and a chance to raise hell in our blood stream like a Girls Gone Wild, MTV beach house weekend.

So with so much diversity B-cells produce a very generalized, one size fits all, meat and potatoes class of antibody referred to as IgM. The structure of this antibody has a lot of arms that are well suited for grabbing hold of more than one antigen at the same time. Then there is the more specific IgG that gets produced in response to repeat offenders, meaning the body built up immunity to that invader and set aside memory b-cells armed to the teeth with antibody “made to order” for subsequent invasions.

yeah that's real clear. Those star fish looking things are the IgM antibodies and they help that enormous white cell to grab hold of whatever nasty bug they attach to

Uh yeah, that’s real clear. So those star fish looking things are the IgM antibodies and they help that enormous white cell to grab hold of whatever nasty bug they attach to

Let’s get back to Allergies!

that handsome devil in the center is the basophil. White cells are actually colorless until a stain is added to the slide. Basophils stain in basic (alkaline) pH, thus baso-phil.

When it comes to allergic responses IgE class antibodies are the usual suspects. They have the ability to activate distinct white cells in our body (Basophils in our blood and mast cells in our tissues) Both of these cells contain granules that when freed from their cellular cages unleash a potent substance called histamine which is primarily responsible for the classic symptoms of an allergic response. Your mast cells and basophils like to hang out on the mucous membranes of the nose, ears, throat, and eyes. These are the access points to your body, places of direct exposure to the outside environment. So these groupings of immune cells are just more likely to have a few run ins anyway with bad boys looking for a fight.

Behind the Scenes

D-awww adorable!

Let’s say you’re frolicking through the fields one day like a happy Jack Russell terrier, kick up some ragweed pollen and think nothing of it. For whatever reason ragweed pollen just rubs your white cells the wrong way (meaning white cells possess a membrane receptor that matches the antigenic determinant of the pollen granule and become sensitized on contact). Over the next few weeks your body will produce a line of B-cell clones that will only produce IgE for that pollen strain which will circulate in your blood stream attaching itself to the membranes of Basophils and Mast cells.

I mean if it’s a choice between land mines and funnel cake I choose cake not war.

These cells literally get coated in IgE like powdered sugar on funnel cake (man that sounds really good right now). So the next time that you’re exposed to ragweed pollen the IgE on those cell membranes grabs a hold of the antigen and triggers the basophils and mast cells to release their histamine granules like land mines.

When Histamine Attacks

The histamine released by your white cells acts on the cells of capillaries. It increases their permeability, opening up the blood vessels allowing white cells and plasma proteins access to the site of infection. This is what we call inflammation. So allergic responses to allergens are an inflammatory process. In the case of a runny nose it is the histamine released by mast cells in your nasal cavity acting on the vessels in your nose. The histamine molecule only has about 17 atoms so it passes quite easily through cellular membranes. A good portion of cold, sinus, and seasonal allergy medications available in the pharmacy section of your grocery store are “antihistamines” counteracting the effects of histamine to relieve your symptoms.

Anaphylaxis

So unfortunately the occasional runny nose isn’t all that allergic responses are capable of and in a select percentage of the population the triggering of inflammation can be a critical and often fatal, systemic reaction. I’m referring to anaphylaxis. This process reflects the most extreme form of immediate immune response whereby widespread inflammation can lead to severe swelling of the eyes, constriction of airways and even shock where the blood pressure drops. Yes, well you know how I like to end things on a light note so….take a look at this beagle puppy playing with a stuffed animal.