The Skin CMR Flashcards
skin weight
10 pounds
skin average surface area
20 sq ft
four categories of skin function
- protection
- sensation
- temp regulation
- metabolic function
skin function: protection
barrier from pathogens, chemicals, physical insults, radiation, and elements. Almost entirely waterproof.
skin function: sensation
collection of sensory data; general sensory afferent nerve endings in skin provide sensations you feel when you cut or pinch a finger, touch a hot surface, etc. nerve endings are sensitive to pain, pressure, and temp
Skin function: temp regulation/water ret
to help warm you up . . .
blood vessels constrict, reducing blood flow to outer skin, retaining warmth.
Skin function: temp regulation/water ret
to help cool you down . . .
- blood vessels dilate in skin, increasing blood flow to skins surface, allowing heat to escape
- sweat glands in the skin increase their secretions, providing cooling as sweat evaporates on the surface.
regular body temp
98.6 F (37 C)
skin function: metabolic
- synethesis of dehydrocholesterol -UV-> previt D -> vit D
- abosrption of medications
deficiency in vit D causes
deformities of rickets, increased risk for osteoporosis
3 distinct regions of the skin
epidermis, dermis, subcutis
external, thinner region of the skin
epidermis
inner, thicker region of the skin
dermis
fat layer of the skin
subcutis
beneath the subcutis is
adipose tissue that binds to muscle
derm/o meaning, darmat/o. cutane/o
skin
epidermis
thin, outer region of the skin made up of dense stratified squamous epithelial tissue. usually in 4 strata.
4 strata of the epidermis
- strata corneum
- strata granulosum
- stratum spinosum
- stratum germinativum
in psoriasis, which layer is thickened?
epidermis
outermost layer of the epidermis, serves as an important mechanical barrier to the external environment. composed of dead flattened cells that have undergone keratinization, and contains keratin, which resists abrasion and forms thick protective layers on skin surfaces subject to friction.
stratum corneum
waterproof protein found in the cytoplasm in stratum corneum
keratin
calluses are thick areas of
keratinized cells
horny layer of skin
stratum corneum
deepest portion of the stratum corneum
stratum lucidum
stratum lucidum
part of the stratum corneum, thin, translucent layer found in skin of soles, fingertips, and palms.
second-most superficial layer of epidermis
stratum granulosum
stratum granulosum
second-most superficial layer; composed of cells with large, visible granules in cytoplasm. these elongated, rectangular cells contain keratohyalin, which contributes to keratinizations
stratum spinosum
third-most superficial layer; composed of 8-10 layers of polygonal cells attached to neighboring cells by intercellular bridges (spiny appearance). this is the midportion of the epidermis, cells closer to the surface of this layer become flattened
third-most superficial layer of epidermis
stratum spinosum
basal cell layer
stratum germinativum
stratum germinativum
single layer of mitotically active columnar cells, which produce new cells at the same rate at which older keratinized cells are sloughed off, thus maintaining a balance. also contains melanocytes, responsible for melanin pigment
how many days does it take to replace skin cells/
28
melanin function
protects DNA, the dermis, and deeper tissues
Skin type I color, photoreactive description
pale, always burns, never tans
Skin type II color, photoreactive description
white, burns easily and tans minimally
Skin type III color, photoreactive description
white (average), sometimes burns mildly, tans uniformly to light brown
Skin type IV color, photoreactive description
beige/lightly tan; burns minimally, always tans well to moderately brown
Skin type V color, photoreactive description
moderately brown/tan; rarely burns, tans easily to dark brown
Skin type VI color, photoreactive description
dark brown/black; never burns, deeply pigmented
dermis
thicker, underlying region of the skin. composed of fibrous, irregularly arranged connective tissue. in contrast to the epidermis, the dermis is rich in blood vessels and nerve endings, as well as skin appendages, hair follicles, eccrine sweat ducts, glands, and sebaceous oil glands
2 layers of dermis
papillary (upper), reticular layer)
papillary layer
upper dermis; consists of papillae arranged in ridges, fingerprints, footprints, etc
reticular layer
lower dermis; tough, white collagenous fibers that provide durability. yellow elastin fibers provide tension and elasticity
stretch marks from pregnancy/obesity are found in what layer
elastic fibers, reduced skin fat/collagen, esp in chronic UV exposure; changes in the reticular layer
subcutaneous tissue
beneath the skin, loose connective tissue and adipose tissue that contains collagenous fibers that extend from the dermis into the subq tissue and over muscles or bone to firmly attach the 2 structures.
the skin is considered an organ because it
consists of multiple structures working as a unit to perform critical/complex functions
