Integumentary System Flashcards
organs of the integumentary system
skin, accessory structures (hair, nails, blood vessels, and nerves)
what tissue types are found in the integumentary system
epithelium - hair, nails
CT - dermis
muscle - attached to hair follicles, arteries and veins
Nervous - nerves for sensation
what membrane describes the integument
cutaneous
functions of the integument
protection, regulation of body temperature, sensory perception, synthesis of vitamin D, emotional, expression, reservoir of blood
three major layers of the skin
epidermis, dermis, subcutaneous (hypodermis)
epidermis
outer, thinner layer, consists of epithelial tissue
dermis
inner, thicker layer, primarily CT
subcutaneous
also called hypodermis, located underneath the dermis, not necessarily part of the skin but shares some functions, mostly loose areola/ adipose CT that anchors skin to underlying structures (mostly muscle), insulates/ absorbs shock
what type of tissue primarily makes up the epidermis
keratinized, stratified squamous epithelium
cell types of the epidermis
keratinocytes, melanocytes, Langerhans cells, merkel cells
keratinocytes
make up most epidermal cells, produce keratin
keratin
tough, insoluble, fibrous protein that provides protection and helps contribute to the the strength and water resistance displayed by epidermis, skin, and nails
melanocytes
produce pigment melanin that protects against UV radiation
Langerhans cells
dendritic cells, macrophages that originated in the bone marrow. Involved in immune responses
Merkel Cells
function in the sensation of touch along with the other adjacent tactile discs (receptors)
types of epidermis
thin (hairy) skin - covers everywhere but the palms, palmar surfaces of digits and soles
thick (hairless) skin - covers the palms, palmar surfaces of digits and soles
Layers of the epidermis
thin skin - four layers
thick skin - five layers
stratum basale (germinativum)
always the deepest epidermal layer, produces all other layer, most metabolically active, one row of actively mitotic cells.mitotic division of keratinocyte stem cells occurs here. MELANOCYTES found here, occasional dendritic cells
mitotic division of keratinocyte stem cell
produces two daughter cells
one goes from basal layer to the surface- takes 25-45 days, dies as it moves toward the surface
one cell remains in the stratum basale as stem cell
stratum spinosum
layer of keratinocytes 8-10 cells deep. unified by desmosomes. Thick bundles of intermediate filaments made of pre-keratin. Abundant in dendritic (immune) cells and melanosome containing keratinocytes
stratum granulosum
typically give layers of flattened cells. keratinocyte cell appearance changes as cells flatten. Nuclei and organelles disintegrate, keratinization begins, helps form keratin in upper layers. cytoplasm full of lamellar granules (release lipids) and keratohyaline granules
why do cells die in layers above stratum granulosum
too far from dermal cappilaries
stratum lucidium
4th layer in thick skin ONLY.
skin of fingertips, palms, and soles
thin, translucent band superficial to stratum granulosum
stratum corneum
alway the outermost layer, approx 20 layers of flat cell remnants. they continuously shed and are replaced by cells from deeper strata. essentially flat membranous sacs filled with keratin. glycolipids in extracellular space
keratinization (cornification)
specialized form of apoptosis, is process of differentiation from viable cells in the stratum basale to keratinocytes in the more superficial layers.
keratinization in the stratum granulosum
cells begin to flatten and their organelles disintegrate. they begin to accumulate a high keratin content
apoptosis
programmed cell death
how are nutrients absorbed in the epidermis
diffusion since it is largely avascular
where are the most nutrients accesible
deepest layers
lack of accessibility to nutrients moving superficially through
the stratum granulosum contributes to what process
keratinization
Lamellar granules within dying/ dead keratinocytes
produce a glycolipid into extra-ceullar space. this coats the external surface of the cells
trans epideral water loss
free water from the dermis continually crosses the epidermis by capillary action and evaporates from the surface of the skin
callus
caused by constant friction. causing thicker build up of keratinocytes in the stratum corneum. mitosis increase in stratum basale in these areas
dandruff
excess of keratinized cells shed from the scalp
types of melanin
eumelanin - brown to black
pheomelanin - yellow to red
what causes freckles
clusters of concentrated melanin triggered by exposure to sunlight. Having more freckles is genetic
nevi
birthmarks/ moles
what causes nevi
chronic lesions of the skin containing melanocytes. Benign by definition
malignant melanoma
cancer of melanocytes
vitiligo
chronic disorder causing depigmentation patches in the skin. pathogenesis is not known
albinism
congenital disorder characterized by complete or partial absence of pigment in the skin, hair, and eyes due to a defect in an enzyme involved in production of melanin
Dermis
rich in CT, contains nerve fibers, muscle, blood, and lymphatic vessels. Abundant in collagen and elastic fibers in the EC matrix (strength and flexibility)
cells found in the dermis
fibroblasts, macrophages, occasionally mast cells and WBC
two regions of the dermis
papillary and reticular
Papillary region
lies just below epidermis. areolar CT with fine interlacing collagen and elastic fibers (loose tissue).
rich in small blood vessels
phagocytes patrol for microorganisms
dermal pappilae
dermal pappilae
superficial peg like projections
in thick skin, epidermis takes shape of undulations of dermal papillae - causes epidermal ridges
collectively called friction ridges
Reticular region
80% of dermal thickness, dense fibrous CT, elastic fibers provide stretch- recoil properties
collagen fibers -strength and resiliency, bind water
cleavage lines - form in directional orientation of collagen fibers in this layer - externally invisible
tears or excessive stretching in region cause stretch marks (striae)
cleavage lines are found in which region of the dermis
reticular
stretch marks or striae are found in what region
reticular
friction ridges are found in which region
papillary
epidermal ridges
reflect contour of underlying dermal papillae and from the basis for fingerpritns and footprints
function of epidermal ridges
increase firmness of grip by increasing friction
lines of cleavage
tension lines in the skin that indicate the predominant direction of underlying collagen fibers
why are lines of cleavage important for plastic surgeons
they make their incision lines parallel to normal cleavage lines to minimize scarring
Subcutaneous layers
also called hypo-dermis
attaches skin to underlying tissues and organs
contains blood vessels and nerves in transit to the more superficial dermal layers
contains lamellated (pacinian) corpuscles
lamelated pacinian corpuscle
detect external pressure applied to the skin
benefits of multiple layers
epidermis -resist damage and offers protection to underlying tissues
dermis - temperature stability and prevents dehydration. limited healing
subcutaneous - insulate, store fat, and anchor to the skin
superficial sensory receptors
merkel discs, free nerve endings, Meissner corpuscles, and hair root plexuses
deep sensory receptors
pacinian corpuscles
Hair
associated with the word pili
present on most surfaces except the palms, nipples, part of genitalia, anterior surfaces of fingers and soles of feet
composed of dead keratinized epidermal cells
helps touch sensation, protects against harmful effects of the sun and against heat loss
what covers the hair making it water resistant
epicuticle, along with insoluble keratin
parts of the hair
shaft - above skin surface
follicle - below surface of the skin
root - penetrates into the dermis (includes epithelial root sheath and dermal root sheath)
two types of hairs
vellus and terminal
vellus
pale, fine body hair of children and adult females
terminal
coarse, long hair of eyebrows, scalp
at puberty appear in axillary and pubic regions of both sexes
what determines hair color
amount and type of melanin
alopecia
hair thinning in both sexes
various causes
androgenic allopecia
male and female pattern baldness
more common in men
caused by follicular response to DHT (dihydrotestosterone)
sebaceous (oil) glands
connected to hair follicles
secrete sebum
prevents desiccation of hair and skin
inhibits growth of certain bacteria
widely distributed
sudoriferous glands
sweat glands
eccrine and apocrine
eccrine sweat glands
most numerous
abundant in forehead, palms, and soles
secrete a water solution that helps cool the body the body and eliminate small amounts of waste
Heat and “cold sweats”
Apocrine swear glands
located mainly in axilla and anogenital region
begin functioning at puberty
secrete a slightly viscous sweat (sweat, fatty substances, proteins)
uses merocrine method of secretion
increased during emotional stress and sexual arousment
body odor is exhibited using which sweat glands
apocrine
modified apocrine sweat glands
ceruminous glands - located in ear canal and produce cerumen (earwax)
mammary gland - human breast milk
mammary glands use what method of secretion
merocrine
nails
hard, keratinized, dead epidermal cells
nail structure includes
free edge, transparent nail body (plate), nail root, nail matrix
white part of the nail is called what
lunula
what part of the nail is living
nail root
types of integumentary wound healing
epidermal - superficial wounds affect only epidermis (normal function return)
deep - injury extends to dermis and subQ layer (loss of some function and development of scar tissue)
epidermal wound healing
common types - abrasions and minor burns
central portion of wound may extend to dermis
process of epidermal wound healing
basal cells enlarge and detach from basement membrane, move towards center of open wound. stop migrating due to contact inhibition (meet cells on other side of wound)
deep wound healing
occurs when injury extends into dermis and subQ layers, healing is more complex, some function may be lost
phases of deep wound healing
inflammatory, migratory, proliferative, maturation
inflammatory phase
increase blood flow to increase inflammation and formation of blood clot
blood cells become more permeable for repair
migratory phase
clot becomes a scab, epithelial cells migrate across the wound, fibroblasts increase in number and begin scar tissue synthesis (collagen fibers and glycoproteins)
proliferative phase
extensive growth of epithelial cells beneath the scab, fibroblasts deposit collagen fibers in RANDOM directions, continued growth and repair of blood vessels to region
maturation phase
scab comes off, epidermis restored to normal thickness, collagen fibers become more organized, fibroblasts decrease In number, blood vessels restored to normal
scar tissue formation (fibrosis)
dense arrangement of collagen fibers
decreased elasticity
fewer blood vessels
lighter appearance due to less blood flow and dense collagen
what causes a burn
excessive heat, electricity, radioactivity, corrosive chemicals
what functions of the skin do burns affects
thermoregulation, protection
first degree burn
only affects the epidermis
characterized by mild pain and redness (erythema)
no blisters
skin function remains intact
second degree burn
destroys epidermis and part of the dermis, some function is lost
characterized by redness, blister formation, edema, and pain
third degree burn
full thickness burn, (all three layers)
most skin function is lost, numbness due to nerve ending destruction
skin cancer forms
basal cell carcinoma, squamous cell carcinoma, malignant melanoma
basal cell carcinoma
about 78% of all skin cancers, tumors arise from stratum basale
rarely metastasize (spread to different areas)
squamous cell carcinoma
20% of skin cancer
arise of squamous cell of epidermis
variability in metastasis
malignant melanoma
arise from melanocytes
2% of skin cancers
metastasize rapidly
most dangerous
nonmelanoma skin cancer
basal and squamous cell carcinomas
highly curable
ABCD of skin cancer
asymmetry, border, color, diameter
effect of aging on integumentary system
subcutaneous fat and elasticity decrease - thin skin
sebaceous glands produce less oil - dehydration and cracking
melanocytes decreases
blood vessels of dermis become more fragile - bruising, bleeding under the skin
risk of cancer increases due to lack of melanocytes and dendritic cells
nails and hair become more brittle
greatest factor of skin changes with age
sun exposure
decubitus ulcer
bed sore, increased susceptibility with age
