Epidermis

Question 1

keratinocytes

Answer 1

majority of cells in epidermis

confer structural properties

Question 2

corneocytes

Answer 2

end product of keratinization

anucleate cells that are shed from skin surface

Question 3

lines of Blaschko

Answer 3

the linear and whorled pattern of migration that keratinocytes follow during embyrogenesis

Question 4

linear epidermal nerves

Answer 4

variant of mole that follows lines of Blaschko and may develop inflammation and itching

Question 5

epidermis layers

Answer 5

stratum basale: cubical cells, prolif function, hemidesm.

stratum spinosum: as cells migrate towards surface they lose water and become flattened, some keratohyaline and lamellar granules present, Langerhans cells, desmo

stratum granulosum: 2-3 cells thick, keratohyaline and lamellar granules

stratum corneum: anucleate cells, varying thickness

Question 6

desmoglein

Answer 6

transmembrane linking protein in desmosomes
desmoglein 1: entire epidermis, concentrates in upper layers
desmoglein 3: basal layer

Question 7

keratohyaline granules

Answer 7

contain profilaggrin (composed of filaggrin) and keratin filaments

filaggrin: promotes aggregation and stabilization of intermediate filaments in cornified layer

Question 8

lamellar granules

Answer 8

aka: Odland bodies
contain lipids, free sterols, hydrolases, ceramics

barrier function and role in apoptosis

hydrolases: contribute to normal desquamation by disrupting intercellular cohesion
ceramides: assist with proper cellular organization

Question 9

keratin

Answer 9

intermediate filament that comprises the cytoskeleton
alpha helical structures (type I-acidic and II-basic)
Type I and II assemble into heteropolymers –> align to make keratin filaments which insert into desmo

Question 10

keratization

Answer 10

enlargement and flattening of keratinocytes as they migrate towards skin

cornified envelope forms from keratin filament parallel assembly and cross linking of proteins

release lamellar granules –> hydrophobic layer

organelles degrade

apoptosis

Question 11

natural moisturizing factors (NMF)

Answer 11

free AA, lactic acid, urea, salts

hygroscopic (attract water) –> epidermis pliability

Question 12

xerosis

Answer 12

dry, rough, scaly skin, sometimes itching

decrease in intercellular lipids and NMF, failure of adherent bods of st. corn. to break down, dehydration of corneocytes

exogenous causes : dry climate, excess exposure to hot water, exposure to detergents/soaps

endogenous causes: atopy, ichthyosis vulgaris, renal insuff, lipid lowering meds, malnutrition

Question 13

transit time from basal to granular layer

Answer 13

12-14 days

*cells in cornified layer take extra 12-14 to desquam

Question 14

atrophy

Answer 14

results from decreased cell prolif

thinning of skin

Question 15

hyperplasia

Answer 15

increase in skin thickness

acanthosis: inc. cell prolif in s. spin.
hyperkeratosis: thickening of s. corn from inc. production of corneocytes or reduced desquam
lichenification: thickening of s. spin. and corn. in response to repeated scratching and rubbing –> leathery and hyper pigmented skin

Question 16

ichthyosis vulgaris (IV)

Answer 16

disorder of cornification

dry skin w/ white, adherent scales fish scales
favors trunk and extremities

retention hyperkeratosis from failure of signals to trigger corneocytes shedding

auto dom w/ variable expression

often improves w/ age

atopic triad association

may have keratosis pilaris

Question 17

keratosis pilaris

Answer 17

follicular retention hyperkeratosis overlying hair follicles of extensors and butt

Question 18

palmoplantar keratoderma (PPK)

Answer 18

hyperkeratosis of palms and soles

auto dom and rec

keratin mutations –> abnorm pairing of type I and II

diffuse: thick, yellow plaques of entire palm, sole, erythema border, excess sweating common
focal: hyperkeratosis on pressure pts
punctate: hyperkeratotic papules and nodules

treatment: topical moisturizers and humectants

Question 19

atopic dermatitis

Answer 19

aka: eczema

part of atopic triad

genetic influence

filaggrin defects

Question 20

psoriasis

Answer 20

inflam disease–> shortened cell turnover time/inc. prolif. (4 days basal to gran)

red plaques, thick and adherent scale, nail changes

Question 21

staphylococcal scalded skin syndrome (SSSS)

Answer 21

malaise, irritability, fever, skin pain

cutaneous erythema starts at head then generalizes

flaccid bullae

caused by exotoxin (ETA and ETB target desmo 1)

inc. risk for:

Question 22

emollients

Answer 22

moisturizer
lotions= least hydrating
creams
ointments=most hydrating

Question 23

humectants

Answer 23

pull water into cells

e.g. ammonium lactate and urea creams