The human body is absolutely incredible and in today's video with the help of the cadavers
here in the lab, we're going to take a look at 20 mind-blowing facts that help illustrate
just how incredible it really is.
Let's do this.
[Intro]
If someone were to have their heart removed, you know, like Indiana Jones style just minus
the forceful entry and bursting into flames, the heart could actually continue to beat
as it does in Indiana Jones for around three minutes and that's because the heart is capable
of what's called self-excitation which is where the heart muscle itself is what determines
when it's going to beat.
This is completely independent of the brain.
Although the brain can come in there and does play a role in some ways at times, I'm just
saying the heart doesn't need the brain beat and this is important because if you had a
head injury and you went unconscious and you couldn't tell the heart to beat, that's a
big problem because neurological tissue can start dying in around 90 seconds or so.
If you could unfold the respiratory tubes within the lungs and then lay them flat, you
would get a surface area around 50 to 75 square meters, which is roughly the same size as
a tennis court.
This is due to the fact that the bronchial tubes have 33 generations.
So, what that means is that the trachea here is one generation and then what happens is
it splits into the Primary Bronchi and that's the second generation.
Then those will split again into the lobar bronchi creating the third generation.
That happens 33 times and it just fills up the entirety of the lungs which is why you're
going to have such a large amount of surface area because 33 generations is just a lot.
Humans are born with around 300 individual bones but by adulthood they reach an average
of 206 bones and that is due to bones actually fusing together to form just larger bones,
but the reason why I say "average" is because variability exist within our species and some
people possibly even you have extra bones that the rest of us don't have and a good
example of this are what are called "Wormian Bones".
Wormian bones are islands of bone that form within the cranial sutures.
These wormian bones can arise anywhere within the sutures and look different from person
to person.
So, some people may have lots of wormian bones while others may only have one or none at
all.
Determining how many skin cells we lose per day is actually a little more difficult than
you may imagine but it's often cited that we lose anywhere between 30 and 40,000 skin
cells per minute which would mean we're losing around 1.8 to 2.4 million skin cells every
single hour which would then mean we're losing between 43.2 and 57.6 million skin cells every
single day.
That's dusty.
The human eye consists of photo receptor cells called rods and cones.
Rods are active during low light situations and cones are responsible for processing color.
However, the human eye only has three types of cones which are sensitive to wavelengths
that correspond to red, blue, and green.
Through color mixing, lighting, and various other neurological processes, it's often cited
that humans can see around one million or so different colors all originating for three
different cones.
The human heart beats between 2.5 and three billion times over the course of your lifetime.
Now, given that the heart pumps around 2,000 gallons or 7,570 liters of blood per day,
that means over your lifetime, this thing is pumping around 55 million gallons of blood
or around 208 million liters of blood.
That is - that incredible.
On average, you breathe somewhere around 20,000 times per day which adds up to 672 liters
or 178 gallons of air, which is enough to fill up 850 balloons.
The human skull contains an average of 22 cranial bones.
Eight of those form what's known as the Neurocranium which is the portion of the skull that protects
the brain and the other 14 form what's called the Facial Skeleton, which is where all the
various muscles attached that allow you to make all these funny faces.
Your epidermis which is the top layer of your skin completely replaces itself around every
27 days or so.
During that time, the cells will [00:04:30]shh dribble, get stuck to one another and then
burst and their fatty insides will waterproof the skin.
If you have a faster turnover, then the 27 days - well, what will happen is the skin
cells can start flaking and breaking off before they actually die which is why you can see
very irritated and even bloody skin.
Your kidneys filter around 190 liters or 50 gallons of blood every single day, producing
around one to two liters of urine during that same time.
The human brain contains 86 billion neurons and averages around 1000 to 10,000 synapses
per individual neuron.
This suggests that there's somewhere between 86 trillion and 860 trillion synapses in the
human brain.
That is more than all the leaves on all the trees in the entire world combined.
Your liver can regrow with as much as 60 to 70% of it being removed.
However, it's not going to be the same shape.
That's because the regeneration is optimized for restoring mass - so, how much of the liver
is there as well as function, not its shape.
So, you could end up with a very non-liver-looking liver.
The spinal cord doesn't actually travel the entire length of your vertebral column.
Instead, it ends about right here at T-12 to L-1 and becomes a whole bunch of nerves.
Now, watch this.
This is one of my favorite structures in the human body and you can see it just kind of
like spreading out.
This is what's called The Cauda Equina and it means horsetail, and this is going to continue
on then towards the sacrum, towards the coccyx, innovating pretty much everything and anything
downstream.
Hiding behind the liver and hiding behind the stomach is this yellow bumpy thing right
here called the Pancreas.
Now, the pancreas produces around one and a half to two liters of digestive juices every
single day.
Now, here's the thing - It doesn't place those digestive juices into the stomach.
Instead, it drops it into the first part of the small intestine here called the Duodenum
and these juices will help break down fats, proteins, and carbohydrates.
An average adult produces about one liter of saliva every single day, which means over
the course of a year, you're producing 365 liters or around 96 gallons of saliva.
Put another way, that is about 28,000 liters or 7,400 gallons of saliva over the course
of a lifetime, which could fill 90 bathtubs up with spit.
The human eye blinks around 15 times per minute, keeping the eye lubricated and free of dust.
That equates to around 900 blinks per hour, 21,600 blinks per day, and around 7.9 million
blinks per year and that - that was exhausting.
Depending on the substance, it can take anywhere between two to eight seconds to go from the
mouth to the stomach via contractions of the esophagus.
That means water, well, will likely go much quicker, probably around that two-second mark
but if you're chewing up some dried-up crackers, for example, that's much more likely to take
around eight seconds.
Neural impulses traveling through a nerve can travel as fast as 250 miles per hour or
402 kilometers per hour, at least at its upper range.
The speed can vary quite dramatically depending on the myelination or basically the fatty
wrapping of the neuron but still, I mean, 250 miles per hour... that's insane.
There's essentially no muscle tissue in the fingers themselves.
All the soft tissue you're feeling is going to be skin, fat, and just various connective
tissues.
The muscle that moves a finger is going to be located in either the dorsal, palmer surface
of the hand or in the forearm and then what will happen is the muscle contracts the tendon
is what actually goes into the fingers that will then move and then you'll have an action
at the joint but it's not from muscle tissue being in the fingers.
Now, I know this is going to break some hearts but this is not the weenus.
This is just elbow skin.
I have no idea where this term "weenus" came from.
It's just elbow skin.
Bite-sized facts like this prepare the mind for full-size portions of information.
There's power in small targeted lessons like this and that's true whether you've never
taken a biology class before in your entire life or if you've taken many biology classes
throughout your educational career and it's also a big reason why we're proud to say that
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Thanks for hanging out with me.
I'll see you in the next video.