Integumentary System: Functions
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Integumentary System: Functions


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.

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