skin
DESCRIPTION
TRANSCRIPT
Integumentary system
•Composed of the skin and a number of skin derivatives (hair, nails, and glands).
•Largest organ in the body
•Accounts for 15 % of body’s weight
Integumentary system
Functions:
1. Protectiona) Physical barrierb) Waterproofsc) Protects against sun’s
ultraviolet light – pigment in the skin called melanin
Integumentary system
Functions:
2. Temperature regulation skin allows body to lose heat by
evaporation, convection, conduction, and sweat
3. Excretion excretes water, fatty substances
and ions
Integumentary system
Functions:
4. Metabolism Vitamin D
5. Absorption if applied to the skin will
absorb Vitamin A, E, and K, steroid hormones released by glands
Integumentary system
Functions:
6. CommunicationStimuli are received by skin
receptors which will communicate with the central nervous system
Integumentary system
2 Layers of the Skin
Epidermis - Top layer of stratified squamous epithelium
Dermis - Layer underneath the epidermis made of connective tissue
Integumentary system
Other parts of the skin:Epidermal – dermal junction is where the epidermis and dermis meet.
Hypodermis – is the layer of tissue under the dermis.
Epidermal-dermal junction
Integumentary system
Two Layers of the Dermis:1. Papillary layer Upper dermis Has ridges that protrude up into
the epidermis called the dermal papillae
It is composed of loose connective tissue
Integumentary system
Functions of Dermal papillae:•Increased blood flow to epidermis
•Increased surface area for dermis and epidermis to connect to each other to hold it strongly together
Integumentary system
Functions of Dermal papillae:
•Contains sensory touch receptors
•Keeps skin from tearing
•Aids in gripping
•Gives you finger prints
Dermal papillae = finger prints
Integumentary system
Layers of the dermis:1. Papillary layer
2.Reticular layer Lower dermis Further keeps from tearing Contains deep pressure sensors Contains sweat glands, lymph
vessels, smooth muscle, and hair follicles
Integumentary system
Layers of the dermis:1. Papillary layer2. Reticular layer
Made of dense irregular connective tissue
Has criss-cross collagen fibers that give it a strong elastic network
This forms lines of cleavage or Langer’s Lines or Line of tension
Langer’s Lines
Note: Incisions parallel to the Langer’s Lines will heal faster and with less scarring.
Integumentary system
HypodermisMade of adipose tissue to insulate and loose connective tissueFunctions to:
1.Conserve heat2.Connects skin to layer below3.Contains blood, lymph, base of hair follicles and sweat glands4. Stores lipids and cushions the body
Integumentary systemHypodermisFunctions to:
Hypodermis is 8% thicker in females than males
Integumentary systemHypodermis
Also known as the subcutaneous tissue
Where medical personal will give a subcutaneous injection because of the rich blood supply
Integumentary system
Blister – a separation between the epidermis and the dermis
Burn - destruction of the different layers of the skin and the structures within the skin.
The severity of the burn is dependent upon the depth of the damage.
Integumentary system
Three Classifications of burns:1. First degree or 1 is when there
has been some damage to the epidermis
Integumentary system
Three Classifications of burns:
2. Second degree or 2 is when the epidermis is completely destroyed and there is some damage to the dermis
Integumentary system
Three Classifications of burns:
2. Second degree
Note: New epidermis will be regenerated from the cells surrounding the hair follicles. The hair follicles are lined with epidermal cells non-keratinized.
Integumentary system
Three Classifications of burns:
3. Third degree or 3 is when the epidermis and dermis are completely destroyed and there is
damage tothehypodermis.
Must have a skin graft to heal.
Integumentary system
Layers of the epidermis:
composed of 4-5 layers depending on the region of skin being considered
Those layers in descending order are the stratum corneum, stratum lucidum, stratum granulosum, stratum spinosum, and stratum basale.
Layers of the epidermis
Integumentary system
Layers of the epidermis:
1. Stratum basale also referred to as "basal cell layer”
is the deepest layer
Single layer of cuboidal/columnar cells that
undergoes rapid mitosis
Integumentary system
Layers of the epidermis:1. Stratum basale
Cells migrate upward from here and begin to differentiate
Also known as the stratum germinativum
Integumentary system
Layers of the epidermis:
2. Stratum spinosum is several cell layers thick
Carries out mitosis as well
Some cells produce Keratin
Integumentary system
Layers of the epidermis:
3. Stratum granulosum flat cells (squamous) Layer where keratinization begins cells overproduce the protein
keratin and smother themselves cells in this layer are beginning to
die
Integumentary systemLayers of the epidermis:
4. Stratum lucidum found only in the thick skin of the
palms of the hand and soles of the feet
cells in this layer are dead
three to four strata (layers) thick
Helps protect against UV rays
Integumentary system
Layers of the epidermis:
5. Stratum corneum outermost layer of squamous cellscells filled with keratin dead cells that have migrated up from the stratum granulosum is true protective layer of skin is 25 – 30 cell layers thick
Integumentary system
Layers of the epidermis:5. Stratum corneum
these dead cells slough off and are continuously replaced by new cells
the sloughing off of cells is known as desquamation
Integumentary system
Layers of the epidermis:5. Stratum corneum
Just for your additional information:
In the human forearm, for example, about 1300 cells/cm2/hr are shed and commonly accumulate as house dust
Desquamation – term in Latin for scaling a fish
Integumentary system
MelaninIs a brown pigment found in the skin and hairprimary determinant of skin colorproduced by melanocytes in the stratum basalethrough phagocytosis vesicles of melanin will enter cells of stratum basale and spinosum
Integumentary system
Melanin
Note: The concentration of melanocytes in the skin of people is about the same, but some don’t produce as much melanin due to genetics.
UV light willtrigger melanin production
Integumentary system
Melanin
Some individual animals and humans have very little or no melanin in their bodies, a condition known as albinism.
There are a number of different types of melanin giving different colors of skin (ex. Eumelanin most common) and hair plus other pigments.
Integumentary system
Skin CancersThere are three main types of skin cancer:
1. Malignant melanoma • cancer cells are found in the melanocytes
• characterized by uncontrolled mitosis of melanocytes in the stratum basale
Integumentary system
Skin CancersThere are three main types of skin cancer:
1. Malignant melanoma usually occurs in adults is the rarest, but worst form of skin
cancer has the highest death rate and is
responsible for 75 percent of all deaths from skin cancer
Usually in fair-skinned people
Integumentary system
Skin CancersThere are three main types of skin cancer: 1. Malignant melanoma
2. Squamous cell carcinomauncontrolled mitosis of cell of the stratum spinosum
Not as dangerous as melanoma, but more dangerous than basal cell carcinoma
Integumentary system
Skin CancersThere are three main types of skin cancer: 1. Malignant melanoma2. Squamous cell carcinoma
95% cure rate when properly treatedmay appear as nodules, or as red, scaly patches of skin
second most common skin cancer found in fair skinned individuals
Integumentary system
Skin CancersThere are three main types of skin cancer: 1. Malignant melanoma2. Squamous cell carcinoma
3. Basal cell carcinomaUncontrolled mitosis of stratum basale layer cells
usually appears as a small, fleshy bump or nodule on the head, neck, or hands
Integumentary system
Skin CancersThere are three main types of skin cancer: 1. Malignant melanoma2. Squamous cell carcinoma3. Basal cell carcinoma
easily detected and has an excellent successful treatment, when properly treated
is the most common skin cancer, but most treatablefound in fair-skinned individuals
Integumentary system
Skin Cancers
Myth: Darker skinned people can’t get skin cancer.The darker the skin the less likely, but the more fatal.Usually melanoma the worst kind.
Usually late diagnosis or diagnosed incorrectly
Integumentary system
Skin CancersMyth: Darker skinned people can’t get skin cancer.
almost always arise on the sole of the foot, palms, fingers, toes, under the nails and mucosal surfaces like in the mouth
Integumentary system
Hair Follicle part of the skin that grows hair by packing old cells together
Cover entire body except eyelids, palms, soles, and lips
Attached to the hair follicle is a sebaceous gland (oil gland)
Integumentary system
Hair FollicleThe thicker density of hair, the more sebaceous glands are found
•Also attached to the follicle is a tiny bundle of muscle fiber called the arrector pili that cause hair to stand up and a goose bump.
Integumentary system
Hair Follicle has two parts based on location:
1. Shaft – protrudes from the skin2. Root – imbedded beneath the skin
At the base of the root is the hair bulb
Integumentary system
Hair has no nerves
Composed of hair structure and hair follicle
Has a protective function
Integumentary system
Hair Strand has three layers:1. Medulla
center layer that is 2-3 cell layers thick
Composed of soft keratin (less sulfur) and air
Integumentary system
Hair Strand has three layers:
2. Cortex middle layerComposed of many cell layersIs hard keratin (contains more
sulfur)Makes up most of hair strandcontains melanin and maybe red
hair pigments
Cortex
2. Cortex
Hair color:•melanin is produced and through
phagocytosis it is incorporated into cells of cortex
•the more melanin the darker the hair color
•red hair also contains a red pigment, the more melanin the darker the red
•gray hair lacks melanin at all
Integumentary system
Hair Strand has three layers:
3. Cuticle outer most layer of hard keratinOne cell layer thick, but cells
overlap like shingles on the roof
Integumentary system
Hair Follicle layers:
1. Internal epithelial root sheath2. External epithelial root sheath
Two layers are covered by dermal root sheath
Hair bulb – expanded end of follicle
Integumentary system
Hair Follicle
Papilla – extends into the bulb and provides nutrients
Integumentary system
Hair Follicle
Hair matrix Is at the base of the hair bulb Where cell mitosis/reproduction
occurs Cells are undifferentiated (all look
the same) Hair electrolysis damages the cell in
the matrix cells don’t reproduce
Integumentary system
Hair Growth
Not all hair grows at the same rate
Eyelashes/brows vs. hair on head
Hair grow and then stops
Integumentary systemHair Growth
Three stages of hair growth:1. Anagen a growth phase when hair is growing
in length Eyelids – spend 30 days in this phase Head strand of hair spends 3 – 7 years
in this phase 90% of head hair is in this phase
Integumentary systemHair Growth
Three stages of hair growth:1. Anagen
2. Catagen
Hair stops growing; transition phase
Club hair or replacement hair is formed
Head hair spend 2-3 weeks in this phase
Integumentary systemHair Growth
Three stages of hair growth:1. Anagen 2. Catagen
3. Telogen Resting phase – 10% of hair on
head is in this phase head hair spends about 100 days
in this phase, eyelids 9 months Hair falls out You lose about 100 hairs on your
head per day
Integumentary system
Nails
Functions:protectionsreinforce the finger/toe tips
Integumentary systemNails
Parts of the NailoNail body – the part that is visibleoNail root – extends underneath the skinoNail matrix – part of nail root where cells reproduce. Cells differentiate and fill with keratinoLunula – upper part of the nail matrix, is thicker and appears white
Integumentary systemNails
Parts of the Nail
oNail bed – thick epithelial tissue that the nail rest on
oFree edge – part that sticks out past the digit
oCuticle – fold of skin on proximal end
Integumentary systemNails
Grow constantly – no growth and resting phases
Grow at a rate of about 3 mm a month
Integumentary system
Glands
Two types based on what they secrete:1. Sweat – water and electrolytes,
sweat
2. Sebaceous - oil
Integumentary systemGlands
Two types of sweat glands:A. Merocrine
Found all over skin, heaviest in soles of feet and palms of hands
Secrete a clear liquid to surface of skin
Are a merocrine gland
Integumentary systemGlands
Two types of sweat glands:A. Merocrine
Regulates body temperature
Smaller and more numerous than apocrine sweat glands
Don’t secrete into hair follicle
Integumentary systemGlands
Two types of sweat glands:
B. Apocrine glands Found armpits, groin and nipples Secrete a milky substance; odorous Actually merocrine glands, but were
once thought apocrine Secrete into hair follicle Found deeper in skin than merocrine
Integumentary systemGlands
Two types based on what they secrete:1. Sweat – water and electrolytes, sweat
2. Sebaceous - oil
Sebaceous glands
Secrete an oily matter called sebum into hair folliclesPore = opening of hair follicle to allow oil to lubricate the skinHolocrine glandsOverproduction of sebum = acne