Okay, now we're gonna discuss the functions of the integumentary system.
And most people think of it as fairly straightforward, in terms of protection.
Protection is one of the key functions of the integumentary system, however,
it certainly is not the only function.
And we'll go into quite a bit more detail in terms of the others, but we're going to
start with protection first, because it is truly one of the most important functions.
Now, first and foremost, I want to start our discussion talking about the proteins
that are associated with the integumentary system, particularly,
with the most superficial layer, the epidermis.
Now, in terms of the epidermis, you're gonna have keratin protein,
this is a very strong protein, it's going to provide the strength and
the protection in that more superficial layer of the epidermis.
We'll talk about that in great more detail in terms of the keratinocytes which
are going to synthesize or produce the keratin.
Now, also in the epidermis, you're going to have lipids.
Lipids are gonna kind of secrete and be around the cells, kind of filling up that
area between cells.
It's important, in terms of not allowing too much stuff in or
too many things out of the integumentary system.
So, if you're thinking about jumping into a pool or
getting into a shower, this is one of the main reasons why your
body doesn't quadruple in size because of the water rushing into your body.
So lipids are extremely important, particularly, in terms of the epidermis.
Now, in terms of glandular secretions, there's two main types.
You're going to have sweat glands, which, in terms of its anatomical term,
it's really sudoriferous, but we'll say sweat glands, here.
And then, oil glands, and these are sebaceous glands.
We'll talk about these in great more detail, but
sweat's gonna play a big role in terms of thermo regulation.
And oil will play a big role, in terms of not allowing
certain things to dry out in your body, particularly, your hair.
And lastly, and also of great importance, is the melanin pigment.
Melanin is going to be synthesized in the melanocytes,
whick are located in the epidermis.
So this is very important, in terms of protection from UV radiation.
It's going to cover up the nuclei of the keratinocytes within the epidermis and
really serve as an important protection there.
Now, another main function of the integumentary system
is as a blood reservoir, and this is, specifically, within the dermal region, so
the layer just deep to the epidermis or what you can actually see.
In a resting adult, about 10% of your blood is actually running
through this area.
So that's a considerable amount of blood.
So, this is gonna serve as an important area.
However, I want to note that in the epidermis, and
this is something that I want to make clear because it's gonna come up over and
over again, the epidermis is actually a vascular.
Which means that there is no blood supply in the epidermis.
So all the blood supply, all the nutrients that you have in the epidermis
has to come from the deeper dermal layer.
All right, also importantly, you're gonna have a role,
in terms of thermal regulation.
And the integumentary system will play a role in various ways.
First, is in terms of sweat.
You're going to sweat when your body temperature rises, and that will allow for
cooling of the body.
Also, as you can see in this visual, you're gonna have what's referred to as vasoconstriction
and vasodilation.
Vasodilation means that the vascular and the dermis will actually widen, and
when it does that, that allows for more blood to move into that area.
With the blood, you have the heat associated with the blood and
that will actually be lost through the epidermis.
So you can think about when vasodilation will occur.
Think about exercising.
In some individuals, your face can get really red.
That's what's occurring, vasodilation.
So allowing for heat loss.
Now, think about the opposite.
If you're out in freezing temperature, your blood vessels will actually constrict
and get smaller, so less blood is running through the dermis.
So it's conserving all of that heat associated with the blood and
allowing it to stay in the deeper layers.
All right, another role in terms of thermo regulation is this last layer
of the integumentary system, which is the subcutaneous layer, we also refer
to this as the hypodermis.
So this is gonna be the deepest layer within the integumentary system.
And one thing I want you to note in this visual is all of this yellow kind of blobby stuff,
and that's fat, also referred to, a more scientific
term as adipose tissue.
So adipose tissue serves as heat storage as well as energy storage.
So depending on the individual, you can have more of the adipose tissue or less.
But very important in terms of thermoregulation, as well.
All right, we'll discuss this in quite a bit more detail, but cutaneous sensation.
Anytime you see cut, C-U-T, that indicates that you're talking about the skin.
So cutaneous sensation, having to do with receiving information [COUGH] from
the external environment and integrating it through the central nervous system.
So, say something, you put your hand on a hot stove,
you're gonna have a signal within the integumentary system that's gonna travel
to your spinal cord, send a signal back telling you to remove your hand.
So you have a fairly complex map, in terms of sensory receptors in this area.
So we'll talk about these maps in a bit more detail, but
it's telling you which spinal nerve or cranial nerve is innovating that area.
So excretion and secretion, as well as absorption, will play a big role, in terms of the functions
of the integumentary system.
So, in terms of secretions, one of the main types of secretion is sweat, so
those sudoriferous glands.
You're gonna have two different types of sweat glands.
You're gonna have eccrine sweat glands, which is what we typically think of when we're
thinking of sweat glands.
The type of sweat that doesn't have much of a smell associated with it,
what happens after you're exercising.
And then you are going to have apocrine secretions.
This happens with sexual excitement or extreme nervousness things like that.
This doesn't happen until after puberty, but these are two of the main secretion areas.
Also, you're gonna have lipid soluble materials, so
when you're talking about oily secretions.
So those sebaceous secretions, and we'll talk about that in quite a bit more
detail later.
Now, in terms of absorption, this can be either a very good thing or a
very bad thing.
So if you're thinking about topical steroids, so putting a topical steroid on
your skin will allow for an anti inflammatory reaction to occur.
So something that can actually be prescribed or
utilized when, particularly, if something is very itchy.
Or it can be in a very bad thing.
So if you think about poison ivy this is being absorbed within to your skin,
within to your integumentary system.
So it can be a good thing and a bad thing, in terms of absorption.
The last function I want to discuss, in terms of the integumentary system,
is the synthesis or the creation of vitamin D.
So, with UV radiation from the sun, you're going to have the activation of a vitamin
D precursor in the skin.
This is gonna start a process that's gonna move through the liver and, eventually,
finish in the kidneys to form the active form of Vitamin D, calcitriol.
Now, Vitamin D plays a huge role particularly in terms of the GI system,
as well as in terms of immune function.
So, hopefully, as we move forward these functions are going
to start making more sense.
We're gonna continue our discussion next with the layers of the epidermis and
the cells.
Then, we'll continue into the deeper layers of the integument.
So dermis and then hypodermis.