Skin Structure and Function Flashcards
About 80-85% of dermis is
type I collagen
thick, dense for support and bulk
Type of collagen in papillary layer
type III collagen
Specialized cells in epidermis
- keratinocytes
- melanocytes
- langerhans cells
- merkel cells
3 factors influence skin color
- melanocytes
- hemoglobin
- carotenes
Keratinocyte growth and differentiation is regulated by
- Calcium second messengers
- immunomodulatory cytokines
K1 and K10 synthesized in which epidermal layer
stratum spinosum
Loricin is produced in the
stratum spinosum
Tonofibrils are characteristic of which epidermal layer
stratum spinosum
Keratohyalin granules contribute
structural proteins (synthesize and store profilaggrin)
Transglutaminase is activated in the _________ layer as what happens?
granular
cells become more permeable to calcium
How does stratum corneum function as a barrier to permeability?
Controlling the:
- loss of fluid
- penetration of noxious foreign materials/radiation
_________ of keratin chains allows them to coil around one another to form a protofibril
heptad repeat structure
Apparent function of keratins in epithelial cells
provide structural framework by connecting desmosomes
Epidermal proteins in keratohyalin granules
Filaggrin, Loricrin, Involucrin
Filaggrin is rich in
histidine
Filaggrin dissociates from keratin when
the arginine side chain is converted to citrulline in lower stratum corneum
Epidermal protein that is a transglutaminase substrate
involucrin
Involucrin is synthesized in
stratum spinosum
Involucrin becomes cross-linked in the ______ layer
granular
Sulfur-rich protein in keratohyalin granules
Loricrin
Cornified cell envelope is surrounded by ________
covalently bound lipid layer of ceramides and fatty acids
Key regulatory mechanisms of keratinocyte proliferation/differentiation
- Nuclear hormone receptors
- calcium second messenger signaling
- immunomodulatory regulation
- cytokines and growth factors
Elias’ studies of calcium effects on skin found that:
-Acute barrier disruption causes ________
^ which coincides with _________
Exposure to high Ca+led to _________
- reduced Ca+ in the stratum granulosum
- lamellar body secretion, decreased mRNAs for differentiation specific proteins
- restoration of mRNAs for differentiation specific proteins
external calcium activates __________ which leads to the activation of _________
CaR
PLC
Second messengers in calcium regulation of keratinocyte differentiation
- IP3
- DAG
IP3 stimulates
release of calcium from intracellular stores
__________ enhances the cellular response to calcium
-Vitamin D
Three proteins regulated by AP-1 transcription factor
Involucrin, Loricrin, Transglutaminase
Protein Kinase C is activated by
increase in DAG and Cai
PKC activates _______
AP-1 family of nuclear transcription factors (genes encoding differentiation specific proteins)
Inflammatory processes involve
- Angiogenesis:
- Influx of what?
- multiplying, leaky blood vessels
- Neutrophil/eosinophil & their inflammatory mediators
Two cytokines produced upon disruption of barrier with irritants like surfactants
- TNF-a
- IL-1a
Th1 are involved with
IL-2
IFN-y
Psoriasis
Th2 are involved with
IL-4, IL-5
Atopic Dermititis
