Introduction to skin Flashcards
epidermis is derived from what embryology
ectoderm
define rete ridges
epithelial extensions that project into underlying connective tissue and mucous membranes
Dermis is derived from
mesoderm
hpypodermis (Subcutaneous layer) derived from
mesoderm
what layer is thicker in thick skin
stratum corneum
which type of skin has stratum lucidium
thick skin
which type of skin has hair follicles
think skin
Meissner corpuscles respond to
slow vibration
texture
Merkel cells respond to
sustained pressure
touch
Pacinian corpuscle responds to
deep pressure
fast vibration
Ruffini endings respond to
Sustained pressure
unmyelinated dendrites of sensory nerve fibers respond to
pain
temperature
Merkel cells synpase with what
meylinated afferent aaxons of dorsal root ganglion cells
where are Merkel cells found
basal layer of thick skin only
characteristics of Stratum corneum
outmost layer
- cornified layer
- dead keratinocytes
Stratum lucidum what is in it
differentiation of keratinocytes
-few melanin granules
what layer do the keratinocytes become flattened
stratum granulosum ( granular layer)
Keratohyalin granules are synthesized from what
bundles of keratin cross-linked with filaggrin
what gives stratum granulosum darkly basophilic granular appearnce
fliggrin attaches keratin intermediate filament
Stratum Spinosum layer consists of what ( spiny layer)
squamous epithelial cells known as keratinocytes
why is the stratum spinosum known as the spiny layer
keratinocytes cytoplasmic projections that form intercellular bridges b/w cells held together by desmosomes
what structure are specialized structures for cell-to-cell adhesion
desmosomes
macular adherens
what cells are found in stratum spinosum
Langerhan cells
Keratinocytes
what are langerhan cells
immune cells derived from monocytes
Keratinocytes contain what
keratin
lamellar bodies
melanin granules
what does stratum basale ( basal layer) contain
kertinocyte stem cells
melanocytes
What do melanocytes contain? what are they synthesized from
melanin
-tyrosine which is from dihyroxyphenylalaline (DOPA)
what happens to the epidermis during aging
thinning of epidermis
what are the two layers of the dermis
papillary
reticular
what does the papillary layer of the dermis contain
Meissner corpuscles
immune cells
what does the reticular layer of the dermis contain
pacinian corpuscles
what is dermal papilla
projections of dermis that interdigitate with overlying epidermis
Primary dermal ridges
have finger/toe prints
what is the fascia divided into
superficial and deep
superficial fascia is also referred to as ? what does it contain
subcutaneous tissue
-areolar and adipose which unites dermis to deep fascia
retinacula
thickened bands of fascia that form restraining bands, such as the extensor retinaculum of the wrist
what is a secondary lesion
modification of primary lesion
Bulla
vesicle bigger than 1 cm
examples of bulla
blisters
phemphigous vulgaris
cyst
elevated, circumsribed, encapsulated lesion of dermis or subcutaneous layer
example of cyst
epidermal inclusion cyst
macule
flat circumscribed lesion that is changed from color of skin
example of macule
freckles
nevi ( small moles)
nodule
elevated, firm “marble-like”, circumscribed lesion
- deeper in dermis than papule
papule
elevated, firm circumsribed area
patch
flat, non-palpable irregularly shaped macule
Petechiae and purpura
red, purple, non-blanching discoloration
less than .5 cm
other name of purpura
bruise and ecchymoses
differential diagnosis for presence of ecchymoses must always include
physical abuse
plaque
elevated, firm and rough lesion with flow top surface
pustule
elevated, superficial lesion similar to vesicle but with plurulent fluid
Telangiectasia
fine, irregular red lines due to capillary dilation
tumor
elevated, solid lesion deep in dermis
vesicle
elevated, circumsribed superficial lesion filled with serous fluid
-less than 1 cm
wheal ( hive, urtciaria)
transient, elevated, irregular-shaped areas of DERMAL EDEMA
how is a wheal formed
MAST CELL DEGRANULATION and HISTAMINE release
what are secondary lesions
modified primary skin lesions
crust
dried serum, blood, purulent exudates
excoriation (scratch)
loss of epidermis leaving linear ling,
erosion
loss of epidermis with glistening, depressed moist appearance
fissure
linear crack from epidermis to dermis
induration
dermal thickening associated with inflammation
keloid
irregular, elevated progressively enlarging scar growing beyond boundary of wound
lichenification
THICKENED EPIDERMIS
scale
heaped up, keratinized cells from corneum
