Ch. 5 Flashcards
skin
1st line of defense, largest organ 7% body weight, last a life time
Accessories: hair, nail, skin gland
Function of Integumentary System Protection
body temperature regulation, Vitamin D synthesis, Sensation, Secretion
Protection- First line defense against bacteria/virus
protect from UV ray and dehydration
Too hot- Dermal vessel dilate
vessel carry blood to surface
Too cold- Dermal blood vessel constrict
Prevent heat escape
Calcium Absorption
Sensory receptor
Waste lost through sweat
Protective function
Mechanical damage- keratin toughen skin
pressure receptor- alert possible damage
Chemical damage- Keratinized cell relatively impermeable
pain receptor- alert possible damage
Bacterial damage- acid seretion inhibit bacteria
phagocyte- ingest foreign substance and pathogens
UV radiation- melanocyte produce melanin
dessication- drying out
keratin- waterproof
Skin Region
Epidermis- superficial
Dermis- underlies epidermis
-made of fibrous connective, nerve, muscle
Hypodermis (SubCutaneous) not skin but share function
- mostly adipose absorb shock and insulate
- Anchor skin to underlying structure-muscle
Epidermis
keratinized stratified squamous epithelium
5 layer- Stratum basale Stratum spinosum Stratum granulosum Stratum lucidum Stratum corneum
4 cell type- Keratinocytes Melanocytes Dendritic (Langerhans) cells Tactile (Merkel) cells
stratum basale (Germinativum)
Deepest epidermal layer
single row of stem cell, actively mitotic, produce 2 daughter cells. 25-45 days to surface dies on journey.
Stratum Spinosum (prickly layer)
several layers thick by desmosomes
web-like system of intermediate pre-keratin
abundant melanosomes and dendritic cells
Stratum granulosm (granular level)
Thin 4-6 layer
cell appearance change- cell flatten
-cell accumulate keratohyaline granules which help form keratin in upper layer
water resistant glycolipid slow water loss
cell above this layer die
stratum Lucidum (clear layer)
only in thick skin, thin, translucent
stratum corneum (horny layer)
20-30 rows of dead anucleated keratin membranous sacs 3/4 epidermal thick
dead but functions: protect from: abrasion, environment and water loss, barrier against bio physical and chem assault.
keratinocytes
produce fibrous protein keratin, most cells of epidermis, connected by desmosomes
pushed upward, become dead scale-like, millions rub off.
melanocytes
10-25% of deepest epidermis produce melanin and protect apical surface from UV
transfer melanin to keratinocyte
synthesize melanin
dendritic (langerhans cells)
macrophage- key activators of immune system
formed in bone
tactile (merkel cells)
sensory touch receptors
spike appearance
connect to nerve cell from dermis
dermis
strong, flexible
2 layers: Papillary and Reticular
contains: nerve fiber, blood and lymphatic vessel, epidermal follicle, oil and sweat gland.
Papillary layer
upper dermal layer (uneven).
fingerlike projection/ indent epidermis/
(Tactile)Meissner corpuscles-light touch receptor
free nerve endings- pain receptor
Epidermal ridges collectively make- friction ridges
- grip, touch, fingerprint
Reticular layer
deepest layer, blood vessel, sweat gland, oil gland
Lamellar Pacinian corpuscle- vibration/pressue receptor
Ruffini ending- skin stretch/ finger position
dense fibrous connective tissue
elastic fiber
phagocyte
cleavage line- most collagen fiber parallel to skin surface.
Skin color pigment
melanin- pigment made in skin, natural sunscreen
carotene- yellwo to orange pigment found in stratum corneum
hemoglobin- oxygen-carrying pigment in bloodcell
Hair
dead keratinized cell of hard keratin
Function: warn of insect, physical trauma, heat loss, sunlight
gray hair- decrease melanin production, increased air bubble in shaft.
hair follicle
dermis and epidermis
hair bulb- hair follicle receptor, sensory nerve endings, hair matrix,
arrector pili- smooth muscle attached to follicle
hair papilla- dermal tissue- blood supply
hair thinning and baldness
alopecia- immune system attacks hair follicle
true baldness- genetically determined
nails
pick small objects, made of keratinized epidermal cells
sweat gland (sudiferous)
all skin except nipple and some genitalia
2 types: eccrine- secret sweat
thermoregulation- sympathetic nervous system
Apocrine- armpit and anogenitalia- sweat fat protein
Sebaceous (oil) gland
widely distributed come from hair.
active at puberty
secrete sebum- oily holocrine, softens hair and skin
burns classification
first- epidermal
second- epidermal and upper dermal
third- entire skin removed, nerve ending destroyed
deep wound healing
injury extend to dermis and subcutaneous layer
