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[Music]
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now that we have completed the mapping
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of the body
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we will now begin our journey through
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each of the body systems
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of which there are 12. our first journey
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begins with the integumentary system
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this body system is divided into three
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major parts
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the skin the hair
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and the nails
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this system is known as a membrane
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because it covers the body
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and an organ because it contains several
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tissues
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for the purposes of this course the
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system will be described as an organ
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with a variety of essential tissues
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the skin is composed by three main
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layers
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epidermis dermis
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and hypodermis
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the epidermis is the outermost layer of
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skin
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this layer is further divided into five
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to six
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thinner layers which do not have blood
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vessels
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only two of these layers of the skin
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will be described
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stratum corneum this is the uppermost
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layer of the skin
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which constantly sheds or where the dead
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skin cells are sloughed off
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essentially the top layer of the skin is
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composed of dead cells
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stratum germinativum
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the stratum germinativum is the lowest
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layer of the epidermis
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and is in contact with the dermis below
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it is the layer in which cell division
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called mitosis takes place
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and where new epidermal tissue is formed
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and begins to migrate to the surface of
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the skin
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replacing the dead skin cells found in
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the stratum corneum
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dermis also known as the corium
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or the true skin this layer contains
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major structures and functions
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for the skin within a framework of
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elastic
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connective tissue this is where the skin
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comes to life
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contained within the dermis are the
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blood vessels
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nerves involuntary muscles
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sweat glands oil glands
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hair follicles and the papilla
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blood vessels via the capillaries
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nutrients are provided to the skin and
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waste products are taken away
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these blood vessels also play a major
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part in maintaining
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and sustaining the body's temperature
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for optimal functioning
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the vessels dilate to release heat
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or they constrict in order to retain the
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body's heat
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nerves allow the skin to have sensory
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perception
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through the skin the body is able to
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respond to pain
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pressure temperature as well as touch
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sensations
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involuntary muscles in the dermis
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control functions such as lifting hair
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or opening pores by dilating
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or opening the pores in the skin the
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body is able to cool off and allow sweat
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to exit
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when the body needs to keep its
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temperature up to prevent heat loss
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these muscles allow the pores in the
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skin to contract or constrict
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in order to keep the heat from exiting
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the body
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in fact if it's too cold these pores can
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constrict
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so tightly that they form what is known
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as goosebumps
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these structures are important for
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keeping and maintaining the body's
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temperature
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which averages at 98.6 degrees
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this helps maintain the process of
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homeostasis
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homeostasis is a major process by which
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the body works
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to keep all of its structures and
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functions in balance
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another way of saying it would be to
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keep the body healthy
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[Music]
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sweat glands or pseudoriforous glands
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are coiled tubes that extend through the
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dermis and
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open on the surface of the skin at the
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pores
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the sweat or perspiration eliminated by
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these glands contain
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water salt and some body wastes
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oil or sebaceous glands
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usually open onto hair follicles these
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glands produce sebum
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an oil that keeps the skin and hair from
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becoming dry
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however due to genetics some people's
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hair
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is more dry than others the dryness is
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determined by whether or not the hair is
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curly
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the curlier the hair the drier the hair
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even when the amount of sebum produced
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is the same
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[Music]
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a hair follicle anchors each hair into
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the skin
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deep into the dermis the hair bulb forms
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the base of the hair follicle
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in the hair bulb living cells divide and
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grow
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to build the hair shaft the hair shaft
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is the hair
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that projects from the skin or scalp
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[Music]
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papilla the top of the dermis is covered
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with papilla
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which fits into the ridges right below
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the stratum german evadum
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the papilla are responsible for creating
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fingerprints
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and footprints like a snowflake
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no one fingerprint is created twice not
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even in twins
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subcutaneous fascia or hypodermis
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this structure is located below the
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dermis or the bottom of the innermost
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layer of the skin
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it is made of elastic and fibrous
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connective tissue
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and adipose which is fatty tissue
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the purpose for this layer is to connect
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the skin to the underlying muscles
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adipose or fat is the yellowish section
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found in this layer we can compare our
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skin
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to a piece of cake epidermis is the
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frosting
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the dermis is the cake itself
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and the subcutaneous or hypodermis is
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the bottom of the cake connecting to the
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pan
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now the hair is the second major part of
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the integumentary system
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the hair's main function is to protect
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the skin hair is composed of a strong
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structural protein called keratin the
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hair grows within a hollow tube called
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the follicle
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here's a little hair trivia for you hair
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can be shaved
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cut styled and groomed but why doesn't
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it hurt when you cut your hair
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the answer is it doesn't hurt when the
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hair is cut because there are no nerves
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but then why does it hurt when you pluck
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your eyebrow or pull a hair out of the
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scalp
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that's because at the base of the hair
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follicle are sensory nerve fibers
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that wrap around each hair bulb
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alright the third major part of the
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integumentary system
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is the nail the nail's main function is
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to serve the fingers and toes
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as protective plates and enhance the
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sensation of the fingertip
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or the toe tip like the hair
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the nail is also composed of keratin
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primarily the nail is made up of dead
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epithelial cells
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packed tightly together to form a
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translucent
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thick dense surface of keratin
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the nail is formed in the nail bed if
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you slam your finger in the door
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you may lose a nail but it will regrow
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if you damage the nail bed however that
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nail will never come back
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before we conclude part one of the
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integumentary system
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let's review there are three main parts
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to this body system
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the skin the hair and the nails
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and the skin has three main layers
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the epidermis which is the outermost
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layer
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the dermis which is just below the
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epidermis
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and contains major structures and
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functions for the skin
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within a framework of elastic connective
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tissue
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and third the subcutaneous fascia
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or hypodermis which is the innermost
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layer
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next we covered the hair whose main
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function is to protect the skin
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and the third major part of the
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integumentary system is the nails
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which serve the fingers and toes as
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protective plates and enhance the
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sensation
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of fingertip or toe tip
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in our next video we will be covering
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the functions of the integumentary
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system
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thanks for watching and we'll see you
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again in part two
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you
