Integumentary System Video Lecture - Science & Technology for UPSC CSE

hi it's mr. Andersen and in this video
I'm going to talk about the
integumentary system which is skin but
it's also hair and nails and what that
does is offer us protection
in other animals that would be made up
of scales or in birds its feathers but
it has not only protection as one of its
functions and that's important it keeps
bacteria out foreign objects outside our
body it also allows us sensations so we
have tactile receptors deep in the skin
that allow us to sense touch and pain it
also allows us to thermoregulate and so
not only goosebumps but we can
vasodilate move blood near the surface
and that carries heat away we could also
have sweat glands that pumps sweat out
and so that as it evaporates carries
heat away and so it's important in
thermo regulation and it's also
important in allowing sunlight in and so
we need sunlight to synthesize vitamin D
if we don't get vitamin D then we can't
bring phosphorus and calcium into the
bones and so we develop a disease called
rickets and so those four things are
super important in the integumentary
system but the whole thing revolves
around the largest organ in your body
which is going to be the skin the top
layer of skin is called the epidermis
and if you get a tattoo we have to make
sure that we're putting that ink
underneath the epidermis if we didn't it
would just simply be lost over time now
the epidermis itself is made up of four
individual stratum which are going to be
layers of cells and if we start at the
bottom we have the stratum basale
that stratum basale is going to be kind
of convoluted over time and so if you
look or over space and so if you look
along the bottom it forms what are
called the dermal papilla and the
function of that as it holds the
epidermis on the dermis which is below
it another important role of the stratum
basale is that it's where mitosis occurs
and so we're creating new cells on the
bottom and then those new cells are
migrating up and eventually we have dead
cells up on the top and so that's where
those new cells are being created over
time on top of that we have the stratum
spinosum and it gets its name from spiny
appearance it has when you were to dye
it with specific dyes what's the
function of that well we need to dig
down a little bit deeper and so for you
to look at the cells down in that basal
layer
then in the spinosum lair up above it
well there's a couple of things that are
going on number one we have these
melanocytes down at the bottom and so
what's that giving us well it's giving
giving us Melania Soames which are
organelles which give off melanin and so
that's going to give us different colors
in skin and so dark-colored skin is
going to have more of these Melania
zomes and more the melanin than
light-colored skin and so that's that
balance remember if your ancestors grew
up around the equator it was important
that more melanin because we could start
to develop cancer and a decreased folic
acid and so birth rates went way down
but as you move to the north the reason
I'm so light in color is that my
ancestors needed to have low amounts of
melanin so I could synthesize vitamin D
so as we keep moving your way up we
eventually get to the granulosa stratum
granulosa minutes and it's granular in
appearance because everything's kind of
getting compressed now how are nutrients
getting up here since there's no
capillaries up in this upper layer of
the epidermis
basically it's diffusion and so these
cells are essentially dying as we move
up next layer is not going to be found
in all skin that's called the stratum
lucidum and so in certain skin we call
that thin skin you only have four layers
on button thick skin you'll have this
additional stratum lucidum so what's the
skin that's so thick that's going to be
in our palms and also on the soles of
our feet it offers us more protection
and then we finally go up to the top we
have stratum corneum and that's going to
be these dead cells and eventually those
leave us but they replace from cells
right below it now that's a lot of
stratum how do you remember it here's a
quick mnemonic come let's get sunburned
is a quick way that you could write
those letters down if you're taking a
test and then you could go through all
the different parts so the B stands for
the basal spinosum granule Oh some loose
it um and then finally the corneum up on
the top now that's just the epidermis
what's below that we have the dermis and
the first thing that's going to jump out
is the vascular tissue so we're going to
have capillaries that reach into the
dermis and so blood is making its way
inside their nourishment is making its
way into the dermis um what are some
other things that jump out right away
we're going to have big glands here so
this would be a sweat gland this would
be a sebaceous gland that's going to
essentially release oil which is going
to keep our hair waterproof and it's
also going to keep our skin waterproof
over time as we look deeper we find
these receptors and there's lots of
different receptors so this yellow right
here would be nerves but we have all
these receptors that are sensing our
environment ones near the top are
censoring light touch and the ones
farther down are sensing deep touch we
also have pain receptors in the skin at
this point keeps us from damaging our
skin as we move farther down we have the
hypodermis which is sometimes referred
to as the subcutaneous and as we move
down in here there's going to be a lot
of connective tissue in here and so
we're going to have these fat cells
we're also going to have some stem cells
that are creating other cells we're
gonna have macrophages that are cruising
around we're going to have lots of
fibers like reticular strong fibers and
then this elastic fiber so when you pull
up your skin it just bounces back to
where it was below before and so that's
the hypodermis and then we have these
accessory structures the big ones are
going to be hair and then nails and so
if we look at a hair follicle right here
way down at the bottom we start to have
capillaries coming in so this is going
to be vascular tissue down here on the
papilla above that we have what's called
the matrix that's going to be one layer
of cells that constantly are making new
cells the cells as they're pushed up are
forming the hair and so the hair is
basically made of dead cells and there's
tons of keratin in there keratin is
what's our fingernails are made up of
and it really makes that durable hair
but as we move up here now the cells are
dead and it's eventually going to move
up past a sebaceous gland remember
that's secreting oil which is delivered
onto the skin and it's also delivered
onto hair making it somewhat waterproof
and then we could look at the nail so
the nail is going to be made essentially
in the same way we have a matrix down at
the bottom and so this pink right here
would be the epidermis but then it dives
down into the dermis and so thus the
nail itself is being created by cells
that are quickly dying they're filled
with keratin then we have the eponym up
on top of that that essentially makes
the cuticle you could kind of see it
right here and then we're going to have
a lot of vascular tissue up here but not
so much right down at the bottom so
that's going to be the in nails where
did they come from they were claws in a
lot of organisms and they allow us to
kind of deal with tools and so if we
were to go through the
view can you remember the three
different layers of skin remember at the
top that's going to be the epidermis
followed by the dermis and then the
hypodermis do you remember the four
layers of the epidermis so come let's
get sunburned allows us to remember that
at the bottom the B stands for basal the
S stands for spinosum the G stands for
granulosa m-- then we've got the lucidum
remember that's only going to be found
in the thick skin and then on the top we
have that stratum corneum which is going
to be the upper layer of our skin and
we've also got the hair and the nails
but that's the integumentary system
it's got fourfold importance and I hope
that was helpful