1: Histology of Skin - Patestas Flashcards
what is the integument?
- skin
- sweat glands
- sebaceous glands
- hair
- nails
functions of skin
- protection
- regulation of body temp
- reception
- absorption
- excretion
describe epidermis
stratified squamous keratinized avascular epithelium
what are the nonkeratinocytes?
langerhans cells (APC) merkel cells (mechanoreceptors) melanocytes
main location of langerhans cells
stratum spinosum and superficial dermis
reside in all layers of dermis
where do langerhans cells derive from
precursors in bone marrow
membrane bound birbeck granules indicate …
langerhans cell
location of merkel cells
- base of hair follicles and fingertips
- attach to keratinocytes by desmosomes
- stratum basale*
melanocytes arise from…
neural crest
location melanocytes
stratum basale* and superficial dermis
what aa becomes melanin?
tyrosine via tyrosinase
melanin granules reside in cell processes of melanocyte
what causes different skin pigmentation
- tyrosinase activity
- number melanin granules
- size
- distribution
- rate of breakdown
- NOT total number melanocytes
decrease or total loss of melanocytes
vitiligo
albinism = melanocytes do not synthesize melanin due to defect or absence of tyrosinase
strata of thin skin bottom –> top
stratum basale "cell renewal" stratum spinosum "binding, protection" stratum granulosum "waterproofing" stratum lucidum "clear" stratum corneum
pearly papule and subepidermal blood vessels
basal cell carcinoma
strata of thick skin bottom –> top
basale
spinosum
corneum
- absence of definite stratum lucidum and granulosum although individual cells are present
“fish like scales”
ichthyosis
- hyperkeratosis (excessive keratin buildup)
dermal papilla correlates with…
epidermal ridge
- areas that are subject to increased mechanical stress display prominent epidermal ridges, dermal papillae and true dermal ridges
layers of dermis
papillary layer - defense against foreign invaders
reticular layer - tensile strength
is hypodermis (superficial fascia) a part of skin
NO
skin = epidermis and dermis
receptors free nerve endings pacinian corpuscles meissner's corpuscles krause end bulbs
- pain and temp
- pressure, vibration
- mechanoreceptors, discriminatory, fine touch
- function unclear
where are apocrine sweat glands located?
axilla, areola, anal region
- merocrine secretory product
normal sweat glands = eccrine
reasons why there is a loss of hair from leg and/or foot:
PAD
diabetes
low thyroid hormone levels
arrector pili muscle
smooth muscle
attaches to hair follicle midway, obliquely and cradles sebaceous gland
nail growth
fingernail - 3.47 mm/mo
toenail - 1.62 mm/mo
pemphigus vulgaris
pemhigus foliaceus
epidermolysis bullosa
- auto ab against desmogelein 1 and 3
- auto ab against desmoglein 1
- genetic mutation encoding for structural prtns such as keratins, collagen type VII or laminin (non-inflammatory blistering disorder)
layer burned in superficial/1st degree burns
epidermis
full thickness burns (aka 3rd degree) extend into subcutaenosu tissue (hypodermis)
epithelial cells aka
keratinocytes
these desquamate every 20-30 days
glues and anchors the epidermis to underlying dermis
basement membrane
true dermal ridges
oriented parallel to and lie in between dermal papillae
dermal ridges are genetically unique = fingerprints
reticular fibers
type III collagen fibers in papillary layer of dermis
where are meissner corpuscles and krause end bulb located?
papillary layer of dermis
where are pacinian (pressure ribration) and ruffini corpuscles (tensile forces) located?
reticular layer of dermis
surgical incisions oriented parallel to __________ produce minimal scaring
langer’s lines
- type I collagen bundles with regular orientation in reticular layer of dermis
describe eccrine sweat glands histologically
- simple coiled tubular glands
- secretory segment = simple cuboidal to low columnar
- duct segment = stratified cuboidal epithelium
nail growth occurs here
nail matrix
forms keratin which forms nail plate
proximal nail fold
eponychium (cuticle, consists of stratum corneum)
crescent shaped area at base of nail, appears white
lunula
3 stages of cutaneous wound healing
inflammatory
proliferative
maturation
