Ch 5 Flashcards
Integumentary System definition
The skin and its accessory structures
Layers
Epidermis, Dermis, Hypodermis (fat layer)
Melanocytes
produces melanin, brown/black pigment which absorbs UV light and is the primary skin pigment.
approx. 8% of Epidermal cells
Epidermis
made up of keratinized stratified squamous epithelium (avascular no bleeding)
Keratinocytes
produce the water-insoluble protein keratin which hardens structures.
approx. 90% of Epidermal cells
Langerhans cells
produced in the bone marrow - travels to skin
helps provide immunity to the epidermis
Merkel cell (disc)
nerve ending for touch (tactile receptors)
Dermis
mostly connective tissue containing collagen and elastin fibers, few cells
Papillary region
superficial portion
Dermal Papillae
tiny projections into the epidermis which increases the surface area of the Stratum Basal
Epidermal Ridges
dermatoglphs = fingerprints assoc. with underlining papillae.
Meissner Corpuscles
tactile receptors located at the apex of the Dermal Papillae
Reticular Region
deepest and largest portion
contain irregular c.t
Deep Wound Healing
Damage effects the Dermis
Hypodermis
composed of adipose and areolar c.t
stores fat
contains vessels and nerves and supply the skin
Superficial healing
only when the epidermis is damaged; cells surrounding the wound enlarge and migrate to fill the gap created by the injury
migration of cells happens and mitosis in Stratum Basal is stimulated more cells are reproduced to make up for the dead cells
Inflammatory Phase
clot forms overwound
local vasodilation, leukocytes (infection) and fibroblasts (rebuild tissue) move into the damaged area
Migrating Phase
scab forms
epithelial tissue migrates beneath the scab to bridge the wound.
granulation (scar) tissue begins to be laid down beneath the scab
vessels begin to grow
Proliferative Phase
epithelial tissue begins to mature
collagen fibers continue to be laid down randomly
Maturation Phase
scab falls after epidermis is repaired
circulation is restored
fibroblasts dec in number.
Fibrosis
scar tissue formation.
Keloid
uncontrolled fibrosis
Thermoregulation
The average temp is 98.6 F; 37 C
Ambient temp is elevated
Perspiration inc, heat is lost by evaporation.
Smooth muscle in dermal vessels relax there diameter to inc. More bl can now enter these vessels.
