St. Patrick's Day is upon us! And while the Irish holiday has a very rich cultural and religious history that should be respected and at the forefront of any celebration, it's also become a day for many to let loose and enjoy themselves an alcoholic beverage or two — or more.
. . In today's video we're going to take a look at the pathway alcohol takes as it travels through your body.
We're going to see the various organs and tissues that it interacts with along that way, and we're even going to discuss that "oh so wonderful" feeling called a hangover. There's a lot to do, so let's do this! First and foremost I have to get this out of the way — alcohol, or more properly known as ethanol — is a legitimate toxin.
While there are studies that have shown that small amounts of daily alcohol consumption can actually be good for you, those studies are pretty inconsistent with each other and you'd be hard-pressed to find anybody willing to say that alcohol is overall healthy for you. And this is not me judging you by the way. Personally, I am a bourbon man.
It's one of my favorite ways to wind down. But there's never been a point as I'm sipping on the bourbon that the cells in my body are like, "yes! !
More toxic ethanol for us to detoxify and potentially get harmed from! ! " But with that said if you are an adult of legal drinking age and you're partaking responsibly, all the power to you!
I'm not gonna get in your way. Just know that it's not good for you. Okay?
Okay! I'm glad we had this talk. To the cadavers!
Obviously the very first place the alcohol is going to enter your body is going to be the mouth or the oral cavity. And we can see that very thing right here. But this is a bisected head in the mid-sagittal plane.
So that means that we've cut it right down the center. And that allows us to see a ton of really cool anatomy such as this gigantic tongue, the mandible here, you can see the roof of the mouth, or the hard palate, and then the soft palate behind it. And then this little flappy thing is called the epiglottis and we'll see that, or more what it does in just a second.
But the thing to really understand is that lining the tongue, and lining the cheeks — in fact lining the entire inner surface of your oral cavity — is mucosal tissue. A mucosal lining that really just kind of helps keep things lubricated, and just humid inside of your mouth. But the thing to understand is that it's capable of absorbing alcohol.
In fact they did a study with some wine tasters to see how much alcohol is getting absorbed when they're doing their wine tastings. Think about it — as they sip the wine they slosh it around, and spit it out, they may not be drinking it but it's spending a considerable amount of time in their mouth and it makes sense to figure out if some of that's been absorbed in the bloodstream. And it turns out, a very small amount is — and I mean a very small amount.
So that means when you're casually drinking, a very extraordinarily small amount of that alcohol is being directly absorbed into your bloodstream from your mouth. But the vast majority of it is going to continue on, and it's going to bypass the tongue and enter this next area called the pharynx or your throat. And that's where that epiglottis is going to come down and block off the airway.
This is the upper portion of your trachea, or your windpipe, and that makes this your voice box, or the larynx. And you obviously don't want the fluid going down into your airway, so the epiglottis diverts it and pushes it into the esophagus — that's what you're looking at here. And the esophagus is your food tube, or I guess in this instance it'd be a food and a drink tube.
In fact, I have another esophagus for us to look at here. Now this is going to look a little weird and be probably somewhat difficult to wrap your mind around, but this portion — this is the larynx, or your voice box, and this is the "Adam's Apple". So that means you're looking at an anterior view of the trachea.
This is the thyroid gland and that makes this part of the tongue. But what we really want to focus on is — I'm going to slide the trachea, and that nerve with with it to the side — and we see this is the esophagus. It's just a muscular tube that is connecting that pharynx up here, all the way down to the stomach.
So the stomach is actually going to be the very first real place that alcohol is going to be absorbed into the body, and it's somewhere around 10 — maybe 15 or so percent. The vast majority of alcohol is going to get absorbed in the small intestine, which we'll see in a second. But you can see on this stomach right here, this — if I can hold this up properly — is the end of the esophagus, and then it turns into the stomach.
And it's just kind of curving over to the right. But this at the bottom — I guess I should say here at the base of the stomach — we have this really important structure called the pyloric sphincter. So this section of the stomach from here until the small intestine starts is called the pylorus, and inside of there is a very strong sphincter called the pyloric sphincter.
And the reason why this sphincter is so important is because it's literally a gatekeeper — that's what pylorus means. If you drink alcohol on an empty stomach, the pyloric sphincter is going to be more open and the alcohol is going to just enter into the small intestine, meaning that on an empty stomach alcohol is going to get into your bloodstream quicker. But if you have food or some other drink, what's going to happen is inside the stomach a bunch of stomach acid is going to be secreted, and this pyloric sphincter is actually going to pinch tight — pinch shut.
And it'll slowly start opening it, kind of just casually opens just a little bit here and there, and that's called gastric emptying. And it's at a very specific rate — well more or less specific — and that means if you have food with your alcohol, it's going to get into your bloodstream, well — delayed. It's not going to happen right away.
At least the majority of it. But like I said, some of the alcohol is capable of being absorbed in the stomach. In fact, I have a different stomach for us to look at — which would be right here if I can get this organized for you — and this stomach has actually been cut.
We've removed the pylorus, and that allows us to do this — this is one of my favorite things, I love this — to reflect it like this. You can see the inside of the stomach. And you're looking at all these folds there, those are called gastric rugae, and that literally means "stomach fold".
They're just really unique and interesting to look at. What I want you to picture is that this entire inside of the stomach is also lined with mucosal tissue. And that mucosal tissue serves a variety of functions.
One of the most important being to actually secrete mucus. And that mucus prevents the stomach acid, or that hydrochloric acid, from consuming the stomach itself. It's kind of an important job.
But the thing to understand is that the alcohol can be absorbed into that mucosal tissue, and then from there it can get into the bloodstream and head to the liver. So you can't — this, this is the entire reason why if you take a drink, after just a couple minutes you're gonna start to feel a rush. That's — even though the majority of the alcohol actually hasn't gotten into your bloodstream yet, some of it has because it was absorbed through the stomach here and then went to the liver.
But the rest of it is actually — if I can pull this back — gonna go into your intestines. And I'm going to kind of bring them all over here. .
. we're going to see this a little more clearly in another cadaver section in a second. But this is where the vast majority of your absorption is going to occur, but that is going to take just a little bit more time to pull off.
So let's go ahead and look at a different cadaver and finish our journey. Quick recap! When you first drink alcohol, it went into your oral cavity or your mouth, some of it got absorbed into the mucosal tissue and went directly into your bloodstream, but it was a very small amount.
You then swallowed it and it went down your esophagus into your stomach. So the stomach on this cadaver here, is going to be located — hopefully you can see this — just like that. This is the stomach.
And it's hiding behind this massive organ that we'll talk about in a second called the liver. But what's going to happen, remember as it sends it into the small intestine, the small intestine are going to do that absorbing. So the first place we can see the small intestine coming out on this cadaver is going to be right here.
Now as I move these small intestines you're going to notice something's different about it compared to the one we just saw in that other dissection. The intestines are attached to your body. This is called the mesentery, and it's — the way I always talk about it with my students is, I say — all those zombie movies?
They're wrong. In the zombie movies you're getting like an abdominal wound, and the guts are just dragging. I mean it's possible — it's definitely possible.
But that's a pretty serious cut. The intestines are attached and they need to be because what they do is they absorb the nutrients. But they have to absorb them to somewhere — bring them to somewhere.
And if you look closely you're going to see all these little blue lines. Those are veins taking whatever they've absorbed — so this would be any food or drink — any nutrients that went into the stomach and got released in the intestines, is going to be absorbed into the mesentery, and is then going to travel to the liver. The same goes for anything that's absorbed by the stomach.
And we did just see that alcohol, or ethanol, is absorbed in some quantity by the stomach itself. So the stomach and the mesentery in the intestines are going to send the alcohol to the liver. And look how big this thing is!
On top of it is the diaphragm muscle that I've scooted up so we could get a pretty good view of this liver here. It's absolutely enormous! This is the second largest organ in the body if you count the skin as an organ.
And this thing is so amazing — it has so many different functions. But one of the coolest properties, I guess you could say of it, is that it regenerates. Most of your body does what's called healing, and healing isn't all that cool.
Healing is a mixture of some regeneration but mostly scarring. Not the liver — the liver is capable of true regeneration and that's because it takes so much abuse. It's not just ethanol — there's other toxins that get into your digestive tract that it has to try and detoxify through some really interesting chemistry.
But throughout all that abuse it could take some damage, so it needs to be able to regenerate. Such an amazing organ! But let's take a step back again.
So the alcohol goes into the liver and this is where it's going to be met with an enzyme called alcohol dehydrogenase. But I should also mention the stomach also had alcohol dehydrogenase. What this enzyme does, is it interacts with the ethanol and converts it into something called acetaldehyde.
Here's the ironic thing — acetaldehyde is actually more toxic than the ethanol itself. And if that's where it was left then we'd have a serious problem. If — if — if we left just the acetaldehyde as it was — oh, you'd be in a world of trouble.
But luckily the liver is also going to have another enzyme that can convert that acetaldehyde into something known as acetate, and the body can easily take care of acetate no problem. Here's the thing — the amount of alcohol you consume, and the time frame you consume it has a pretty strong influence on the liver's ability to convert it all the way into acetate. So what will happen is you drink it, it gets absorbed, it's permeating the tissues, but it isn't able to handle the entire workload all at once.
So some of that ethanol is gonna make its way into the bloodstream. Because the liver is then gonna send the blood directly to the heart — and that's what this gigantic thing is here, I'll kind of remove this — this is the pericardium. You can see the heart here, and what's going to happen is the heart is then going to beat and send that blood directly to the lungs right next door.
And this is how alcohol can be on your breath. Because as the ethanol gets in — it's, remember it's in the blood, but it's going to go to the lung tissue, and inside of the lungs you have all these hollow air sacs that are surrounded in capillaries. And what will happen is the ethanol will evaporate into those little air sacs, and then as you breathe out — so kind of picture if this could inflate — and then as you breathe out and it kind of gets squished what's going to happen is that ethanol is going to go up your respiratory tract and it's on your breath.
This is the entire premise behind a breathalyzer and why it works. So — kind of interesting that way — that you can actually get rid of alcohol when you are drinking. You're getting rid of alcohol by simply breathing it out.
But not all of the ethanol is going to do that. The rest of it's going to go back to the heart and then when that heart contracts it's going to send the blood all the way up straight to the brain, and then start distributing it throughout your entire body. And this is something that's so important to take note of — ethanol is going to interact with pretty much everything in your body except for bone tissue, because it's just so hard, and fatty tissue.
Because you have to understand ethanol is water soluble and fatty tissue is made of lipids and oil and water do not mix. If you've ever done that experiment maybe back in elementary school. So sure — some ethanol can get into your fatty tissue, but it's a very small amount.
But everything else in your body. . .
so like I just said — your lungs. . .
I don't know if you'll be able to see this all that much — I'll kind of pull this tissue to the side — there's this organ down here called the spleen. Your gallbladder. .
. everything in your body is going to interact with the ethanol. To what degree does the ethanol have an effect on it?
There's a lot of factors that go into it. It depends on how vascular that organ and structure is in the first place. It depends on your genetics.
. . it depends on your overall health.
So it's hard to give you a real solid answer on that. But a real interesting one is what it does to muscle tissue. Actually I should probably take a quick step back.
We're going to see the brain here in a second, but you need to understand that ethanol actually stimulates what's known as your sympathetic nervous system. This is your "Fight or Flight" aspect of your nervous system. And what that means is it's going to accelerate the heart rate.
So the heart's going to just start beating, and as it starts beating it's going to start pushing the blood even more forcefully to things like muscles. It's also going to cause you to sweat. This is why if you're drinking you'll start sweating because your sympathetic nervous system is "going off".
But think of all the ethanol that is hitting the skeletal muscle tissue. And that can actually have an effect on protein synthesis. So let's say you went to the gym earlier that day and you got a really great workout in, and then later that night you decided to have a few drinks.
Well those drinks could possibly negate maybe not entirely but a significant portion of your gains, because the alcohol prevents proteins from being built inside of the muscle tissue. Absolutely fascinating what's going on there! So all right — alcohol is now — if we kind of take a step back to kind of make this kind of a process.
. . alcohol is now heading straight for the brain.
So what we're going to do is we're going to jump on over to some brains and check it out. Okay! So blood is pumping straight to the brain and that's what we have here.
So this upper portion is called the cerebrum, it's highly folded and such an amazing structure — in fact I did an entire video on just this one section here called the prefrontal cortex, so you should definitely go check that out after this video. This lower portion is called the cerebellum. But what we really want to look at because it's so cool, is if I flip it over, you can see that there — if you look closely that is — there's this gray outer portion and then this white inner portion.
This is gray and white matter respectively. The gray matter is where the cells of the brain called neurons are communicating with each other. So picture billions upon billions of connections all happening in just this tiny little area I'm traversing with the probe, and that's where they're just talking.
And they talk with the use of something called neurotransmitters. And I guarantee you've heard of neurotransmitters before. The two most famous are probably dopamine and serotonin, but there's other ones like GABA and glutamate, that ethanol is also going to affect.
And ethanol is also going to affect the secretion of endorphins, which — let's put this all together. So without getting too granular or nitty-gritty, you're gonna have pleasure, you're gonna have euphoria, you're gonna have lowered inhibitions, and you're gonna have lowered cognitive ability and lowered reflexes. When you bundle it all together — so basically think about it like this.
. . When you lower inhibitions, that's when things you start start saying and doing things that you normally wouldn't do.
When you're drinking alcohol also you get this great idea — "what if I took off my pants, I jumped on the table, and i just screamed, I'm King of the World! " Anybody who's not drinking, that is a terrible idea. But someone who's five shots of tequila in, that's smart!
Not only is it smart, it's necessary! That just goes to show your choice-making ability has gone out the window. But you're literally thinking slower.
You're also euphoric. You're happy about it! It's a really strange combination.
But that is only the effect that it has on the neurological tissue — it's also going to affect your hormonal system. So what I want to do is look at another dissection, and it's that sagittal head that we've already seen, so we can focus on these two structures here. So this first one that I'm traversing with my probe is called the hypothalamus, and this is going to be just above another really famous one known as the pituitary gland.
Together they form what's known as the hypothalamic-pituitary axis. And that's a big word that's really not all that necessary to remember. Just understand that these two structures control your entire hormonal system.
The hypothalamus is more or less in charge of the pituitary gland. So it'll secrete hormones that boss around the pituitary gland. But the hypothalamus is constantly monitoring your body.
So when you start drinking, the hypothalamus is aware of it and it's going to start adjusting based off of the ethanol. In fact it's going to basically tell the pituitary gland to start bossing around your adrenal glands. And your adrenal glands are what secrete cortisol, which is your stress hormone and epinephrine and norepinephrine — also known as adrenaline.
So think about this. . .
when you drink — not only do you have diminished choice making ability, your inhibitions are gone, but now you're stressed and you have adrenaline coursing through your system. If you remember just a moment ago we talked about the sympathetic nervous system and the heart rate increasing and all that. So this is a pretty potent mixture.
But not only that, the pituitary gland is also going to slow down its secretion of a hormone known as anti-diuretic hormone. So a diuretic is something that causes you to urinate. So anti-diuretic hormone would mean that you would hold on to water.
But what instead happens, is ethanol influences the secretion of ADH, and that's going to have a pretty big effect on your kidney. See the kidney is going to — this is a really cool dissection. So you can see a bunch of amazing structures in here, and these are just renal pyramids.
And this outer portion is called the cortex of the kidney and inside of here are all these tiny little filtration units that are filtering blood. You see, blood gets pumped — let's see if I can grab this — through this artery here called the renal artery. And that is then going to go to the outside of the kidney and get filtered into urine, which will then be dropped down this long tube called the ureter, and then the bladder, and then the outside world.
That means your urine was once blood. Well — now, the ADH isn't being secreted, the blood vessel — so think about that — so another name for ADH, or anti-diuretic hormone, is vasopressin. And I like that name because it sounds like you're pressing on blood vessels.
Because that's what it'll do. It'll actually constrict the blood vessels inside of the kidney, meaning less blood volume is able to go and get filtered, meaning you make less urine. But if you're drinking alcohol what's gonna happen instead is you are going to be peeing a lot.
I remember I used to — before I knew any of this years ago, I used to be confused. . .
like I'd have one beer. . .
like I'd try to do the math in my head. I'm like, "okay. I drank that much.
. . but I peed that much.
. . " It never made any sense to me, but that's because of the lowered ADH.
But what that means is you are now dehydrating yourself. You're getting rid of all this fluid — and more fluid than you're bringing in through the alcoholic beverage. That also means the inside of here — without getting too nitty-gritty into it — in order to make this whole process efficient, the kidney is going to start dropping electrolytes into the urinary tract.
And so that means as you urinate, you're going to start losing electrolytes. And this is going to be kind of important when we're talking about — or may be important — with hangovers. But just think about it like this — not only are you dehydrated, you're also lowering your ability to rehydrate because electrolytes are what attract water back into your body.
So I'm sure you're starting to see where this is all going. . .
you're jacked out of your mind on adrenaline and stress hormone. . .
you are making bad decisions, you're happy about it, and you gotta pee all the time! I mean, if that does not sum up the alcohol experience, I don't know what does! At the same time though, alcohol doesn't affect every single individual in the exact same way.
There are certain things that affect how it effects you. So for instance, sex is a large one. You see, females have a higher body fat percentage.
And so let's say, I had a male and a female who weighed the exact same and they drank the exact amount of same amount of alcohol. Well what would happen, since the female has a higher body fat percentage, that also means she actually has less blood volume. So that same amount of alcohol is more concentrated in her lower blood volume than it would be for the male, meaning it can actually affect her more intensely.
But things like age are also going to play a giant role. You have things like genetics. There's certain people that just aren't able to produce the enzymes in enough quantity to properly break down alcohol.
Like we mentioned earlier — do you have food in your stomach? Do you have drink in your stomach? These things are all going to play a pretty big role.
But we haven't even talked about what happens after all of this. . .
after all the fun — the hangover. Hangovers are actually still pretty mysterious. We have general ideas, like I can tell you a hangover is essentially because you're dehydrated, lack of sleep, just maybe physically beat up because who knows what you're doing.
. . like jumping on tables saying you're the "King of the World".
We can say like generally there's all these little things that add up to create the hangover. But if you actually start trying to break down specific pathophysiology — the real causes — it gets kind of hard to figure out what's going on. One of the leading culprits — at least what we think — is that acetaldehyde that we mentioned earlier.
So remember, acetaldehyde is more toxic than the ethanol itself. And so the idea is that too much acetaldehyde can actually start to create that hangover, or at least some of the symptoms of that hangover. Which I should probably mention the symptoms!
I mean they're going to be things like — and these are everybody's favorite, right? You've all been there. Diarrhea, nausea, possible vomiting, just fatigue — you're just exhausted.
And you have an extreme loss of appetite, which is interesting because if we're talking about how to overcome the hangover, there's also not a lot of real understanding as to what can solve it other than time. I don't about know you, but I've heard probably every single remedy under the sun. I used to be in the United States Marine Corps, and if any of you know about United States Marines — we like to drink.
And so I remember hearing so many different remedies after a weekend of just harsh inappropriate drinking. And my go-to was actually — please don't judge me too harshly for this — my go-to was about as greasy of a breakfast sandwich from McDonald's as I could possibly get, and then some kind of sports drink like a Gatorade or Powerade. And I did that because someone told me that would fix it at some point, and I just kept on doing it.
There's no evidence that that actually helps all that much. Some people will say coffee. Some people say a shower.
Sleep is obvious — that's definitely going to help. But the only thing that's actually been proven, is time itself. You have to wait it out.
If you if you're just depending — there's no magic pill. Although, I am curious to see if you can leave it in the comments below what you may have heard, or what you do, or what you swear by, because don't get me wrong — like I still to this day, despite everything I know. .
. if I do have a hangover, my first inkling is I gotta go get some really gross breakfast sandwich, and that's gonna fix it. And what's funny is it never does, but I keep doing it anyways.
Again — please try not to judge me too harshly. . .
Thanks for watching everyone! I had a blast filming this video, but I wanted to take a moment and just give my thanks to those who donate their body's to science. Because while I'm trying to make this lighthearted and fun so we can at least enjoy this, I also want to be respectful and understand the amazing gift that they have given.
Because without their generous gift, we wouldn't be able to show these types of things. What I often tell my students is — five minutes with a kidney, or five minutes with any structure really, you learn more than in five hours in the classroom. Or maybe you learn something different that you just couldn't learn in the classroom.
And so as fun as we're having with this video, it's nice to be able to see these structures so you can better understand and hopefully make better decisions with your drinking. Especially with St. Patrick's Day, or I don't know — maybe it's Wednesday — for any of you.
But again, I just wanted to extend my thanks and gratitude to those who donate their body's to science. But as always, please like, comment, subscribe if you haven't already. Which if you haven't — what are you doing?
We try to make videos like once a week. Sometimes twice a week. And if the stars align, we would love to push it to three to four videos per week.
But make sure you hit that notification bell so you'll be the first person to see the videos as they come out. But if you're gonna go drinking please, do so responsibly. And try not to take your pants off and say you're King of the World.
. . If you don't do that, as far as I'm concerned — it's a win.
