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We all know that we need to be drinking water but why do we need to be drinking water?
What makes it so important?
What is the body even do with it and what happens to the body when you don't have enough
of it?
Are these simple questions?
Maybe.
But they're important questions that everyone should have the answers to and in today's
video, we're going to use the cadavers to take a look at what happens to water once
it enters into the body through the digestive system.
We'll see how the brain even understands that you need more or less water, how the kidneys
respond to the brain's instructions, and we'll even see what happens to cells when they have
too much, too little, or just the right amount of water.
It's going to be a fun one.
Let's do this.
[Intro]
Thirst occurs when there's a need for an organism such as you to find and consume water.
As you probably already know, without water, you'd die within a few days, depending on
the exact circumstance.
I mean, if you're in the Sahara Desert with no protection from the elements, you're likely
to die a whole lot quicker than you would if you were in other environments but all
in all, you tend to die within a few days.
In contrast, humans can survive without food for weeks to months at a time.
Again, depending on the exact circumstances.
Water is just very, very important and you find in two places in the body - you can find
it inside of the cells or what we call the intra cellular space or you can find it outside
of the cells, in what we call the extra cellular space.
Roughly two thirds of your total water volume is going to be located in the intra cellular
space.
Meaning, most of your water is going to be in the cells of your brain, your heart, your
lungs, your kidneys, so on and so forth.
The remaining one third will be found outside of your cells.
So, think like your connective tissues.
Now, this means, depending on the type of dehydration you're experiencing, you could
actually experience different types of thirst - an intra cellular thirst or an extra cellular
thirst.
Let's say that if your cells become dehydrated, often times, simply drinking water can be
enough to replenish them.
However, if you lose blood because blood contains water, let's say you get a cut on your arm,
that could mean that you need water and salt to help regenerate the blood at its correct.
This could mean you might need a meal to go with your water to fully "quench your thirst"
although I'm not entirely sure that's the best way to describe it.
You might be wondering how much water you should be drinking per day.
That's actually a little more difficult to answer than you may think and that's because
it depends on a variety of factors.
What altitude do you live at - Believe it or not.
Um, how old are you?
Are you menstruating?
Do you consume alcohol?
How physically active are you?
The list goes on and on and while these are all important questions to ask, I personally
don't find them necessary to ask in the beginning.
Instead, you want to focus on building the habit of drinking water to start off with
and then start to dial in the exact amount you need for you as a person based on your
individual circumstances but that's true of health and wellness in general.
If you want to make an overall improvement in your health, well, first, you need to educate
yourself as to why it's actually important and a good idea to make that improvement and
then, you need to build a healthy habit off of that and then you can even start to expand
later on down the road.
It's, to me, undeniably the best way to go.
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Now, let's go ahead and jump over to a cadaver section of the brain and see just how the
body monitors hydration levels.
You're looking at a mid sagittal cross section of the human head, meaning we've cut it right
down the middle.
So, to quickly inches so you know what you're looking at, this is the anterior direction,
this is going to be the nose, this is that nasal septum and then we're heading in the
posterior direction and this really cool looking structure here is called the cerebellum and
then right in front of it is the brain stem but our focus today is going to be in this
little region right here.
So, specifically what I'm tracing with my probe is a region called the hypothalamus
and then just below the hypothalamus is a really fascinating gland the pituitary gland.
Now, both of these structures together form what you can think of is like a bridge between
the neurological or nervous system like the brain that I'm touching with the probe here
and your glandular hormonal endocrine system like the adrenal glands for instance.
So, these two structures together form a bridge and what's going to happen is the hypothalamus
is going to communicate with the pituitary gland and then that pituitary gland will start
sending out signals.
Now, the message is it's communicate are typically based around something called homeostasis.
So, you can think of homeostasis as your body's natural balance or you know, as close to being
balanced as possible and the hypothalamus job is to try and bring the body back to homeostasis
or at times, actually bring it away from homeostasis.
It really depends on the circumstance but a real easy thing to wrap your mind around
would be like body temperature which is about 98.6 degrees Fahrenheit or I think it's 36
to 37 degrees Celsius.
I forget which one it is but the body or the hypothalamus will deviate from that based
on demand.
So, maybe say if you're hot, then, it will recognize that as you're going above that
temperature and it will start to initiate sweating to help bring you to cool down.
Well, what goes with that homeostasis is going to be water regulation.
Now, the term we're actually going to use here is osmoregulation.
Now, to understand what that means, we first need to discuss something called osmosis.
Simply put osmosis is the diffusion or movement of water from one area to another based around
electrolyte concentration.
Now, you've probably heard of electrolytes before.
It's probably in sports drinks but these are going to be things like sodium, chloride,
potassium to name a few and they are all over the body.
They are extremely important for cellular function and just performance and in this
instance, they are essential for monitoring and regulating hydration levels.
So, inside of the hypothalamus which again is going to be this region right here, there
are go to be cells in there called osmoreceptors which are - that's probably going to make
a lot of sense to you - Osmo in this instance is for osmosis.
Now, these osmoreceptors are actually stretch sensitive neurons and what happens is they
are capable of actually determining how much water and how much electrolytes are overall
in the body based around how many - how much water and electrolytes are inside of them.
So, think about it like this - if there is not a of water, those osmoreceptors will actually
shrink and that will send a signal down to this area right here called the posterior
pituitary and tell it to secrete a hormone called anti-diuretic hormone.
You've probably heard of diuretics before.
A diuretic is something that causes you to urinate.
So, an anti-diuretic hormone would cause you to not urinate or retain your water.
So, if you don't have enough water, it makes sense to not urinate.
You don't want to lose anymore so what will happen is that will go down to the kidneys
and say hey let's not urinate.
But, let's say you have too much water, that would then cause those osmoreceptors to start
to swell, right?
They start to bloat and that itself would also send a signal down to this posterior
pituitary and say "Hey, make less anti diuretic hormone", because if you make less of it then
obviously you're going to urinate more and you can start to lose water.
It's all about balance.
Remember, it goes back to that term that we just mentioned, homeostasis.
Now, osmoreceptors aren't the only ones in the body monitoring hydration levels.
In fact, they belong to a larger regulatory pathway called osmoregulation.
One other example of neurons that are osmo regulatory are what are called baroreceptors.
These are going to be located inside of blood vessels, specifically arteries like the aorta
which is going to be coming out from the heart and they are monitoring blood pressure.
So, I mean, picture this, right?
There's water in your blood.
So, if you have too much water in the bloodstream, that's going to elevate blood pressure and
these baroreceptors are also stretch sensitive and they are going to detect that and they
are then going to initiate a series of events that is going to be osmoregulative.
At the same time, let's say maybe you get cut - I don't know, maybe like in the knee
or something along those lines and you're bleeding.
Well, you are now losing water and so what's going to happen is you're going to have a
slight decrease in blood pressure.
Those baroreceptors are also going to sense that and once again they're going to become
osmoregulative.
You're looking at a kidney that's been cut in the frontal or coronal plain which means
it's been divided into front and back portions.
Now, I'm going to give you a quick tour of the kidney because there's a lot to look at
here.
So, this is called the renal artery and what it does is it brings unfiltered blood to the
kidney because that's what the kidney does, it filters your blood and this renal artery
is going to start splitting and it splits many different times until eventually these
tiny little blood vessels get to outer rim which you can see.
This distance here is called the renal cortex.
This is where all the really interesting stuff happens inside of the kidney and that's because
there are these tiny little filtration units located in here that we can't see which are
called nephrons.
They're going to filter the blood and then that newly filtered blood will basically take
the same return trip except instead of going in the arterial system, it's going to go in
the venous system which is - if I can grab it - that's this one behind it right there.
Now, when it filters the waste out, it's going to drop it into this darkened inner core of
the kidney.
This region here is called the renal medulla and the renal medulla is made up of these
individual renal pyramids.
That's what all these darkened portions are.
The renal pyramids are basically just made up of all these little tubes.
What will happen is the waste product will drop into the collecting tubes and then go
down into the urinary tract and that's what here which will eventually go down to like
the urethra and then down to the bladder.
Now, in terms of osmoregulation, that is going to occur here in that renal medulla.
So, what you have to understand is that the tissue of the kidney itself is going to be
naturally salty.
It's going to have a bunch of sodium and chloride inside of there and that is going to attract
water.
So, just think about it like this - if you have too much water, what will happen is the
kidney will actually put the salt into the collecting tubes and that will attract water
into those renal pyramids and then you will urinate out the excess water.
Now, if you are dehydrated, what will happen is that salt will move into the - more so
into the kidney tissue and the water will come with it.
So, the water will go into the tissue of the kidney which will then find other accessory
blood vessels and be returned to the body.
So, you can think of all the osmoregulation of the kidney happening here in that renal
medulla.
So, what does dehydration do to the body?
Well, it depends on again, the type of dehydration that's happening to you.
Remember, blood loss actually is a form of dehydration and with enough blood loss, you
have some pretty severe problems on your hand but it also might be important to discuss
the different ways you can lose water to begin with because you don't just lose water through
urination.
You lose water through breathing and speaking, through crying, through sweating and it's
not just water you're losing in these instances either, you're also going to be losing electrolytes.
Remember, those salts are what attract water to it and so in order to get rid of the water,
you're also going to be getting rid of some of those electrolytes which is going to definitely
alter and affect that osmoregulation pathway.
So, it depends on the form of dehydration - are you just dehydrated from water?
Are you just dehydrated from electrolytes or is it both?
And in what amounts?
But in the end, it's going to affect the of the cells, the individual cells themselves.
How much is it going to affect their performance?
Again, it also depends, right?
I mean, just think about the common symptoms you see with dehydration - headache, dry mouth,
lips, eyes, you can get a darker color of urine.
I'm sure you've all seen that where that's because there's a high - when there's less
water content in the urine and there's a higher density of other things, it just tends to
look darker but you're also going to get confusion, you'll get fatigue and the worst the dehydration
get, the worst these symptoms will get to the point where it's not just confusion in
the late stages of dehydration, it's borderline delirium to the point where you're psychotic.
So, what's happening to the body?
Essentially, you're just dying and you're dying very slowly in the initial stages and
then you're dying very quickly in those later stages.
Thanks again to the sponsor of today's video Noom.
Be sure to click the link in the description below and take their quick and easy free evaluation
and you can start building better health habits today.
As always, be sure to like, comment, subscribe if you haven't already and just good luck
hydrating out there folks.
Be sure to consume electrolytes on top of that water to optimize `these hydration levels
and I will see you in the next video.