Epidermis Flashcards
Keratin of stratum basale
K5, K14
(Also K1, K6 in dogs)
What are the 2 types of keratinocytes in stratum basale?
1) Stem cells (slowly dividing)
2) Transit amplifying cells (rapidly proliferating)
What is an Epidermal Proliferative Unit?
Progeny of 1 original stem cell, transit amplifying cells –> terminally differentiated cells in all layers of epidermis
What are the spines in the stratum spinosum?
Desmosomes
What are the keratins of stratum spinosum?
K1, K10
(also K4, K15, K16 in dogs)
In what layer is involucrin made?
Stratum spinosum
In what layer is profilaggrin made?
Stratum spinosum
In what layer are lamellar granules made?
Stratum spinosum
Products of the stratum spinosum (3)
1) Involucrin
2) Profilaggrin
3) Lamellar granules
What is present in keratohyalin granules? (3)
1) Profilaggrin
2) Keratin filaments
3) Loricrin
In which layer does the cornified cell envelope construction begin?
Stratum granulosum
Where are lamellar granules released?
Apical side of stratum granulosum (into base of stratum corneum)
-Plasma membrane fuses to release into intercellular space
What is inside lamellar bodies? (10)
1) Sphingomyelin
2) Glucosylceramides
3) Phospholipids
4) Cholesterol
5) Proteases (steroid sulfatase, phospholipase A2, sphingomyelinase, β-glucocerebrosidase)
6) Protease inhibitors
7) Kallikreins = proteases for desquamation
8) Cathepsins = proteases for desquamation
9) Corneodesmosin
10) AMP’s and beta defensins
11) LEKTI’s
What is in the extracellular lipid matrix? (3)
1) Ceramides
2) Fatty acids
3) Cholesterol
Which cytoskeleton components are used for intracellular transport?
1) Microfilaments (actin)
2) Microtubules (α-tubulin, β-tubulin)
Which cytoskeleton components are used for scaffolding?
Intermediate filaments (keratin)
pH of Type I keratins
Acidic
Size of Type I keratins
Smaller
Numbers of Type I keratins
K9-19
pH of Type II keratins
Basic
Size of Type II keratins
Larger
Numbers of Type II keratins
K1-8
What type of keratins form heterodimers?
A type I keratin (acidic, K9-19) dimerizes with a type II keratin (basic, K1-8)
Parallel alignment
What is the progression of keratin assembly (classic model)?
Type I and Type II keratin line up → antiparallel heterodimers → tetramers → protofilaments → protofibrils → keratin intermediate filaments