McGuffin Part 1 Flashcards
function of skin
Absorption Protection Sensation Temp regulation Vit D production
Epidermis
ectoderm
rete ridges
Dermis
mesoderm
Hypodermis
aka subcutaneous layer
mesoderm
Thick skin
palms/soles
epidermis is thicker, esp stratum corneum
prominent epi/dermal ridges - fingerprints
contains merkel, meissner, pacinian corpuscles in dermis and hypodermis
Stratum lucidum PRESENT
MULTIPLE sweat glands
NO hair follicles
FEW melanocytes
Thin skin
thin stratum corneum
no stratum lucidum
MANY hair follicles and melanocytes
FEW sweat glands
Mechanoreceptors for touch and pressure are dendritic endings of what nerve fibers
afferent
what causes neurons to degenerate when over expressed
Sodium Channel BNC1 (degenerin)
Meissner corpuscle
-encapsulated in CT
Slow vibration
Texture
Merkel cells
synapse w/ DRG
basal layer ofthic ks kin only
Sustained pressure
Touch
Pacinian Corpuscle
unmyelinated
encapsulated by concentric lamellae of CT
Deep pressure
Fast vibration
Ruffini endings
elongated capsules
Sustained pressure
Unmyelinated dendrites of sensory nerve fibers
located around hair follicles
Pain
Temperature
Stratum corneum
outermost/fully differentiated
desquamation of dead keratinocytes (flat)
wearing surface for skin
Stratum lucidum
only in thick skin
continuation of differentiation (keratinocytes (flat) to stratum granulosum)
Stratum Granulosum
keratinocytes become flattened (programmed destruction of nucleus/organelles) Keratohyalin granules (from keratin/filaggrin crosslink) darkly basophilic granular appearance - filaggrin attaches keratin to desmosome for mechanical strength of epidermis
what allows for waterproofing
lamellar bodies release lipid into intercellular spaces in stratum granulosum – seals spaces between cells
Stratum Spinosum
several layers of squamous epithelial cells: keratinocytes – has cytoplasmic projections. forms intercellular bridge held by desmosomes
cell-cell adhesion
desmosomes/macula adherens
Langerhan cell
derived from monocyte
APC
all layers of thick and thin epidermis, mainly in stratum spinosum
Keratinocytes - components
Made by keratinocytes:
- Keratin: protective protein. composed in part by intermediate filaments of cytoskeleton
- Lamellar bodies: lipid filled, non-membrane bound
Made by melanocytes, taken up by keratinocytes:
- melanin granules
Stratum basale
single layer
Cuboidal cells - hemidesmosomes
- keratinocyte stem cells
- melanocytes
cell-ECM attachment
hemidesmosome
melanin derived from
neural crest cells
tyrosine – DOPA
protects DNA, absorbs/scatters UV radiation
Two forms of melanin
- Pheo-melanin: red-yellow
- Eu-melanin (brown-black)
Normal aging of the skin
- 30-35 yr
- thinning of epidermis
- reduced subcut fat, BV, hair foll, seb glands, sweat ducts
- loss of collagen fibril production —> wrinkles
layers of epidermis - top to bottom
Stratum:
- Corneum
- Lucidum
- Granulosum
- Spinosum
- Basale
STILL NEED DERMIS/HYPODERMIS/FASCIA
Dermal layer:
- papillary layer: loose, ir CT.
Meissner
- Reticular layer: dense ir CT. Dermatan sulfate, large collagen fibers in parallel/longitudinally in limbs, circumferentially in neck/trunk. Elastic fibers.
Pacinian
Rete ridges vs dermal papilla
Rete: epidermal downgrowths btwn dermal papillae, divides primary dermal ridge
Dermal papilla: projections that interdigitate overlying epidermis
Finger/toe prints
primary dermal ridges
- two dermal papilla with intervening rete ridge or interpapillary peg. Carried to surface of the epidermis
Found in Hypodermis
- adipose tissue
- BV
- Fat
- Loose CT
- nerves
All three layers of skin are receptive to touch, pain, temp
T/F
True
potential tracts for spread of infection
deep fascia
eg retropharyngeal abscess
