Anatomy and Physiology of the skin Flashcards
What are the 4 main types of cell junctions in the skin?
Desmosomes/hemidesmosomes, adherens junctions, tight junctions, gap junctions
What do desmosomes attach to connect cells?
They anchor/attach to keratins
What proteins make up the desmosomes and which ones are cytoplasmic and which ones are transmembrane?
Cytoplasmic: desmoplakin, plakophilin, plakoglobin
Transmembrane: desmocollin 1/2/3, and desmoglein 1/3
What do adherens junctions attach/secure to?
Actin filaments
What ion is required for desmocollin, desmoglein and other cadherins need to function?
Calcium
What proteins make up the adherens junction? Which are cytoplasmic and which are transmembrane?
Cytoplasmic: alpha-catenin, beta-catenin, plakoglobin
Transmembrane: Cadherins (E and P)
What protein make up tight junctions?
Claudins and occludins
In what layers are tight junctions and what is their purpose?
They are a tight seal against water LOSS and they are in the granular cell layer
What are the gap junctions made up of?
Connexons (6 connexons make up a junction)
What keratins are produced in the basal layer?
5/14
What enzyme is upregulated in the epidermis during states of proliferation and what medication inhibits it?
Ornithine decarboxylase is expressed more during hyperproliferative states.
-It is inhibited by corticosteroids, retinoids, and vitamin D3
Why are multiple pilomatrixomas associated with myotonic muscular dystrophy, Rubenstein-Taybi, and gardner syndrome?
Pilomatricomas are associated with disruptions in beta-catenin signaling, these are all associated with issues in beta-catenin.
Note also associated with sarcoid and turner syndrome
What is the transit time from the basal layer to the stratum corneum? What about to complete sluffing/desquamation?
14 days for the basal layer to stratum corneum, 14 days in the stratum corner, so 28 days from basal layer to desquamation
What types of keratins are produced in the stratum spinosum?
Keratins 1/10
What causes the terminal keratinocyte differentiation in the stratum spinosum and where does this occur?
Increased intracellular calcium in the suprabasal epidermis
What are Odland bodies and where are they produced?
These are lamellar granules w/ lysoome-like properties that are made in the spinous layer
What is the primary component of Odland bodies?
Ceramide (which is the most important lipid in barrier function)
-Also contain glycoproteins, glycolipids, and phospholipids
What are Odlund bodies in terms of organelles and where do they exert their effect?
Specialized lysosomes, their action is exerted in the stratum corneum
-Products are released in the junction between the stratum granulosum and statum corneum
What do ceramides help form?
The cornified cell envelope –> replaces the cell membrane eventually
What two diseases are caused by decreased lamellar granules?
Flegel’s disease and Harlequin ichthyosis
What are contained within the keratohyalin granules in the granule cell layer?
Profilaggrin, loricrin, keratin intermediate filaments, and involucrin
In what layer does the production of the cornified cell envelope mostly take place?
In the granular cell layer
What is the most abundant component of the cornified cell envelope?
Loricrin
What are the first early components of the cornified cell envelope and where do they form?
Envoplakin, periplakin and involucrin create scaffolding along the inner cell membrane (the inner cell membrane ultimately get’s replaced by ceramides from lamellar granules)