skin has … (number) layers
3
skin layers:
- epidermis
- dermis
- subcutaneous fat (hypodermis or subcutis )
subcutaneous fat of skin is also called 3
hypodermis or subcutis
epidermis layers - from surface to base (only the names)
- stratum corneum
- stratum lucidum
- stratum granulosum
- stratum spinosum
- statum basale
epidermis layers - statum corneum is characterised by
keratin in anucleated cells
epidermis layers - stratum lucidum is characterised by
dead skin cells
epidermis layers - stratum granulosum is characterised by
granules in keratinocytes
epidermis layers - stratum spinosum is characterised by
desmosomes between keratinocytes
epidermis layers - stratum basale is characterised by
stem cells
skin function
barrier against environmental insults and fluid loss
dermis is seperated by epidermis by
basement membrane
dermis consists of
connective tissue, nerve ending, blood and lymphocyte vessels, adnexal structures
dermis - adnexal structures
hair shafts, sweat glands, sebacous glands
adnexal structures in greek
εξαρτηματικές δομές
epidermis layers - desmosomes between keratinocytes
stratum spinosum
epidermis layers - granules in keratinocytes
stratum granulosum
epidermis layers - dead skin cells
stratum lucidum
hyperkeratosis - definition
increased thickness of stratum corneum
examples of hyperkeratosis
- psoriasis
2. calluses
parakeratosis - definition
hyperkeratosis with retention of nuclei in stratum corneum
parakeratosis - example
psoriasis
spongiosis - definition
epidermal accumulation of edematous fluid in inter-cellular spaces
spongiosis - example
eczematous dermatitis
acantholysis - definition
hypergranoulosis - definition
acantholysis: seperation of epidermal cells
hypergranoulosis: increased thickness of stratum granulosum
acantholysis example
hypergranoulosis - example
acantholysis: pemphigus vulgaris
hypergranoulosis: liches planus
acanthosis - definition
epidermal hyperplasia (increased spinosum)
acanthosis - example
acanthosis nigricans
patch - definition
flat lesion with well-circumscribed change in skin color, >1 cm (macule but >1cm)
macule -definition
flat lesion with well-circumscribed change in skin color less than 1 cm
patch example
large birthmark (congenital nevus)
papule - definition
elevated solid skin lesion
papule example
- mole (nevus)
2. acne
plaque - definition
elevated solid skin lesion more than 1cm (papule but more than 1cm)
plaque - example
psoriasis
vesicle - definition
small fluid containing blister less than 1 cm
bulla - definition
large fluid containing blister more than 1cm
bulla example
bullous pemphigoid
vesicle - examples
chickenbox (varicella)
shingles
wheal - definition
transient smooth papule or plaque
wheal - example
Hives (urticaria)
pustule - definition
vesicle containing pus
pustule - example
pustular psoriasis
scale - definition
flaking off of stratum corneum
scale - example
eczema
psoriasis
SCC
crust - definition
dry exudate
crust - example
impetigo
transient smooth papule or plaque - terminology
wheal
dry exudate in skin - terminology
crust
epidermal hyperplasia (increased spinosum) - terminology
acanthosis
increased thickness of stratum granulosum - terminology
hypergranulosis
Epithelial cell junctions - types (from apical to basolateral nmz) and there other names
- Tight junction (zonula occludens)
- Adherens junction (belt desmosome, zonule adherens)
- Desmosome (spot desmosome, macule adherens)
- Gap junction
- Hemidesmosome
- Integrins
Epithelial cell junctions - tight junctions are also called
zona occludens
Epithelial cell junctions - tight junctions are composed of
claudins and occludins
Epithelial cell junctions - tight junctions - function
prevents paracellular movement of solutes
Epithelial cell junctions - adherent junction location
below tight junction
Epithelial cell junctions - adherent junction function/structure
forms belt connecting actin cytoskeleton of adjacent cells with cadherins (E-cadherin and actin filaments)
Epithelial cell junctions - cadherins characteristic of their action
Ca2+-depended adhesion proteins
Epithelial cell junctions - loss of E-cadherins –>
metastasis
Epithelial cell junctions - Desmosomes are also called
macula adherens / spot desmosomes
Epithelial cell junctions - desmosomes - location
stratum spinosum
Epithelial cell junctions - desmosomes - function/structure
structural support via keratin interactions (keratin and demsoplakin)
disease associated with desmosomes
autoantibodies against desmosomes –> pemphigus vulgaris
autoantibodies against desmosomes –>
pemphigus vulgaris
Epithelial cell junctions - gap juctions - structure
connexons (channel proteins)
Epithelial cell junctions - gap juctions - function
permit electrical and chemical communication between cells
Epithelial cell junctions - hemidesmosomes - location
between basal cells and basement membrane
Epithelial cell junctions - hemidesmosomes - function
connects keratin in basal cells to underling membrane
Epithelial cell junctions - hemidesmosomes related disease
autoantibodies against hemidesmosomes –> bullous pemphigoid
autoantibodies against hemidesmosomes –>
bullous pemphigoid
Epithelial cell junctions - integrins - function/structure
membrane proteins that maintain integrity of basolateral membrane by binding to collagen and laminin in basement membrane
Epithelial cell junctions - desmosomes structure
keratin and desmoplakin
Epithelial cell junctions - adherens junction - structure
E-cadherin and actin filaments
pigmented skin disorders - types
- Albinism
- Melasma
- Vitiligo
albinism - mechanism (not the causes)
normal melanocyte number with decreased production of melanin
causes of albinism
- decreased tyrosinase activity
- defective tyrosine transport
- failure of neural crest cell migration during development
albinism increases the risk of
skin cancer
melasma is also called
chloasma
melasma (chloasma) appearance
hyperpigmentation
melasma is …. associated with ….
hyperpigmentation associated with pregnancy (mask of pregnancy) or OCP use
melsasma (chloasma) associated with pregnancy is also called
mask of pregnancy
vitiligo - appearance
irregular areas of complete depigmentation
vitiligo is caused by
autoimmune destruction of melanocytes
epithelial cell junction - zonula occludens
tight junction
epithelial cell junction - zonula adherens
adherens junction
epithelial cell junction - macula adherens
desmosome
spongiosis - definition
epidermal accumulation of edematous fluid in inter-cellular spaces
macule example
Frenkle
labial macule