A 6 Skin as a Protective Barrier Flashcards
Name the 4 Cornified envelope proteins?
- Loricrin
- involucrin
- keratolinin
- transglutaminase 1 catalyzes cross-linking of the above 3.
Corneocyte Intercellular lipid matrix (ex: ceramide) is released from?
-Lamellar granules (a.k.a. membrane coating granules, or Odland bodies). This is the mortar of stratum corneum.
Main lipid in stratum corneum?
Ceramides. (a sphingolipid)
Describe the 3 diseases of the stratum corneum. (Don’t need to know these!!)
- Staphylococcal Scalded Skin Syndrome (splits skin just below stratum corneum, sloughs off. Fluids barrier disrupted.)
- Lamellar ichthyosis (mutated transglutaminase 1, so no cornified envelope. Get large plate-like scale and ectropion.)
- Harlequin fetus (Auto recessive. Lamellar granules absent. No intercellular matrix. Severe ichthyosis, a.k.a. scales. Malformed ears, eyes, mouth.)
Do glycoproteins belong to lamellar granules, or keratinohyalin granules?
-Lamellar granules. This is the exception, where a protein is in the lamellar granules.
Which epidermal cells are interdigitated?
-Corneocytes
Desmosomes are present mostly in which epidermal layers?
All but most superficial stratum corneum
Elasticity of stratum corneum comes from what?
-H20 filled in among corneocyte proteins
Skin temp is okay in this range without damage.
20-40 C
Heat exchange w/ environment mainly happens where:
- Cutaneous blood vessels
- Eccrine sweat glands
In cold environments, what happens in skin?
-Sympathetic stimulation. Vessel constriction. Flow down.
Max sweat rate? Controlled by?
- 1.5 liter/hr. 10X normal heat loss rate.
- Controlled by hypothalamus.
What results from UV acting on dehydrocholesterol?
-Cholecalciferol. (Vit D3)
Vit D3 activation sequence
- 7-dehydrocholesterol: ring break by UV to…
- Cholecalcieferol (D3): hydroxylated in liver to…
- 25 hydroxycholecalcieferol: Hydroxylated again in kidney to…
- 1,25 dihydroxycholecalcieferol: Finally active.
- Acts to absorb and reabsorb more Ca from intestine and kidney.
Langerhans do what?
- Present antigen to T cells
- Delayed hypersensitivity reactions
- Immunosurveillance against viruses
Langerhans located in dermis or epidermis?
Other “inflammatory cells” located in dermis or epidermis?
Langerhans=epidermis (for our purposes)
“Other cells”=dermis (lymphocytes, histiocytes, neutrophils, eosinophils, mast cells)
UV Spectrum wavelengths (in nm)
UVC=200-290 (ozone absorbed)
UVB=290-320 (“burning”)
UVA=320-400 (“tanning”)
-memory helper: ABC by energy level. (high freq= high energy)
Chromophores
-Absorb light, excite. Then release in 1 of 3 ways:
A. Photochemical rxn: Make pyrimidine dimer or free radical
B. Photosensitized rxn: Transfer the energy to another molecule
C. Shed as heat
Sunburn redness is due to?
Vasodilation, mast cell degranulation.
3 skin cancers
- basal cell carcinoma
- malignant melanoma
- squamous cell carcinoma
What Absorbs UVB in epidermis?
- Melanin
- Keratin, keratohyalin, nucleic acids, nucleoproteins, urocanoic acid
UV that penetrates past epidermis?
- 5-10% UVB
- 50% UVA
Function: Lamellar Granules vs Keratohyaline Granules
-Lamellar: Lipid contents maintain vapor barrier with signaling cell turnover. (Mortar)
-Keratohyaline: Deliver free amino acids to the outer layers of the st. corneum. (filaggrin monomers)
Conversion of profilaggrin to fillagrin. epidermal osmolarity and flexibility
Where do you find birbeck granules?
In langerhans cells
Keratinocytes release an inflamatory response through what?
IL-1
