Apr9 M2,3-Histology of Skin Parts 1 and 2 Flashcards
1
Q
skin type of epithelium
A
stratified squamous keratinized epithelium
2
Q
keratinization def
A
- killing of cells by massive cross linking of cytoskeletal proteins and other proteins in the cell
- the cell dies
3
Q
metaplasia def
A
- deviation from normal in epithelia
- can result in tumor cell migration or metastatic cells (skin cells are doing displacement, not migration, as they mature to the surface)
4
Q
keratins = what kind of protein
A
keratins = gene family that is part of the intermediate filaments category (that make the cytoskeleton)
5
Q
equivalent of epidermis and dermis in the mouth
A
epithelium and LP
together, form the mucosa
6
Q
hypodermis content
A
layer of adipocytes
7
Q
(IMPORTANT) layers of the epidermis (base to top)
A
- stratum basale or germinativum
- stratum spinosum
- stratum granulosum
- stratum lucidum
- stratum corneum
8
Q
epidermis and dermis interactions and significance
A
- interdigitate between each other
- epith protrusions in dermis = rete pegs
- dermis protrusion in epith = dermal papillae
- allows better exchange with lymphatics and caps
- gives fingerprints
9
Q
stratum granulosum charact + next step
A
- cells have granules
- will do massive cross-linking and change their cytoskeleton to form the next layer
- will form stratum lucidum
10
Q
melanocytes location in the skin + start what cancer
A
- epidermis
- along the stratum germinativum (basale)
- send processes that insert between the cells
- start melanomas
11
Q
2 main proteins in dermis + 2 layers of the dermis
A
- collagen and elastin
- papillary (closest to BM) and reticular
12
Q
dermis papillary layer (closest to the epidermis, BM) content and reticular layer content
A
- papillary = small type 3 collagen fibrils (reticular fibers)
- reticular = type 1 collagen
13
Q
BM charact
A
- EC matrix with collagen, elastic tissue
- porous supporting plane + solid attachments
- serves as attachment point for cells
14
Q
how basal cells attach to the BM + name of the attachment
A
- use a R on their surface called an integrin
- binds ligand in BM matrix
- HEMIDESMOSOME
15
Q
desmosome fct and contents
A
- cell-cell connection
- EXTERIOR = CADHERINS of each cell for attachment (cadherin-cadherin)
- INTERIOR = cadherins attached to plasma membrane and to a circular structure under the membrane.
- cytoskeletal elements (interm filaments and keratin) attach to circular structure
16
Q
charact of cells in stratum spinosum
A
send protrusions
17
Q
diff proteins in the papillary layer (right under BM)
A
- type 3 collagen (reticular fibers)
- type 7 collagen (forming velcro loops)
- elastic fibers (elastins)
- collagen IV (type 4)
- laminins
18
Q
tonofilaments def and location
A
- cytoskeleton expressed from particular keratinocyte genes and that cross-links and forms fibrils
- are the keratins of the intermediate filaments that attach on the cytoplasmic circular structure in hemidesmosomes or desmosomes
19
Q
most important protein the skin expresses
A
keratin (to make a solid barrier + involved with lipids)
20
Q
2 major families (names) of the cadherins of the epidermis (for desmosomes, cell-cell)
A
- desmogelins
- desmocolins
21
Q
charact of the space between the cells formed by a desmosome
A
- water impermeable glycolipid deposition place
- specific lipids secreted there
- these lipids assemble in lamellated granules (discs)
22
Q
cell-cell interaction general rules in the whole body
A
- 2 integrins on same cell form cis-dimer
- 2 cis-dimers from 2 diff cells interact together IF ARE OF THE SAME KIND
- interaction is CALCIUM DEPENDENT
23
Q
how cadherins interact in the epidermis vs in the rest of the body
A
- rest of the body = expressed all around the cell
- epidermis = form specific regions called desmosomes
24
Q
charact of the granules in the stratum granulosum
A
- called keratohyalin granules
- NOT membrane bound
- are an accumulate of proteins around tonofilament
25
major protein in the keratohyalin granules of stratum granulosum
filaggrin
26
how cytoskeleton and keratohyaline granules start cross-linking in stratum granulosum
transglutaminases are enzymes that make irreversible covalent bonds between them
27
important thing that must happen for the skin to slough off + consequence of genetic disease in that
- desmosomes must detach
| - defect = bacterial infections
28
stratum lucidum charact
- in thick skin (sole of feet and palms)
- are a massive-cross-linking
- cells there are DEAD
29
name of the cells in the stratum lucidum
squames (skin sloughin off = cell desquamation)
30
2 proteins other than keratin known to be part of the stratum corneum enveloppe and to cross-link also
- loricrin
| - involucrin
31
epidermolysis bullosa def
- blistering disease of the skin in response to minor trauma
| - bc of an adhesion disease of the skin, skin not tough enough. shearing. mechanical tears
32
basal cell vs squamous cell CA
- basal cell CA of the skin = starts in stratum basale cells
- squamous cell CA of the skin = starts in stratum spinosum (higher layer)
* squamous more dangerous*
33
adenoCA of the skin def
CA starting in epithelium of the glands
34
what determines ability to heal after a burn
- how deep
- how wide
* important for determining if you destroyed stratum basale cells and how much bc are important for regen*
35
warts def
- circular ingoing benign infection with HPV
- perturbation of the process of cross-linking
- scaly lesion
36
blisters def
mechanical separation of the skin
37
psoriasis def
itchy patches. immune disease of T cells activation where they prolif too much
38
epidermolysis bullosa on histology
- massive bleeding and hemorrhage
- skin sliding above BM
- ripped, cracked epidermis
39
ichtyosis def
- mutations in intermediate filaments (Interm - Ichtyosis. i-i) OR filaggrin OR transglutaminase mutations
- problem of keratinization process
40
melanocytes function
- make melanin granules, which protects DNA from UV light by ABSORBING UV light
- granules are placed between the nucleus and the outer surface of the skin (to protect from UV light)
41
how melanin is produced
- golgi involved
- tyrosinase is produced (enzyme) and is packed in vesicles
- tyrosin vesicles are also formed
- the two premelanosome vesicles fuse forming a melanosome
- tyrosinase converts tyrosin to melanin to form a melanin granule (melanosome)
42
how melanin granules protect keratinocytes if they're only produced by melanocytes
- melanocytes projections between keratinocytes
- melanocytes release their granules outside of the cell
- granules are engulfed by cells of the stratum spinosum
- melanosomes moved above nucleus
43
embryologic origin of melanocytes
neural crest cells (NCCs)
44
difference in melanocytes cell-cell attachment
doesn't do desmosomal connections with keratinocytes
45
albinism cause + thing to be careful about in this disease
- mutation in tyrosinase gene (partial or complete)
| - higher risk of skin cancer
46
abundant cell type in the dermis and that is also the ''grandfather'' of all cells
fibroblasts (or fibrocytes)
47
function of fibroblasts
- make type 1 collagen (reticular dermis)
- make type 3 collagen (reticular fibers in papillary dermis)
- make type 7 collagen loops for papillary dermis
- etc
48
cell that fibroblasts originate from and what other cells can this ancestor give rise to
undifferentiated mesenchymal stem cell. can give
- fibroblast
- adipocytes
- macrophage, histiocyte
- mast cell
- plasma cell
49
name of components of collagen
- collagen fibrils (=seen on EM)
| - many fibrils from collagen fibers (seen on LM)
50
structure of the collagen molecule
- 3 protein chains forming a triple helix (collagen tropomolecules)
- released in exocytic pathway
- self polymerize to form fibrils
51
time to make collagen and why
60 mins
- post translational modifications (PTMs)
- must form triple helix
- exists in pro-granules initially
52
what cells make AND turn over collagen
fibroblasts
53
how fibroblasts turn over collagen
with enzymes like collagenases and MMPs
54
bone structure
- collagen matrix
- calcium phosphate crystals bind on the matrix
- cracks on the surface and banding pattern
- osteoclasts and osteoblasts
55
structure of teeth enamel and dentin and pulp (EM)
- enamel = exterior = dead
- dentin = odontoblasts, cell processes and nerves going through holes occupied by odontoblasts
- pulp = matrix of EC collagen
56
important molecule in collagen synthesis
- vitamin C
| - important cofactor in collagen triple helix assembly in the cell
57
examples of diseases if you lack vit C, Ca or copper (most visible signs you get)
get a collagen deficiency
- teeth falling out bc held to jaw by periodontal (suspensory) ligament
- knees faling out (defective ACL)
58
how collagen fibrils cross-link
lysyl oxidase protein does that
59
2 main components of the ECM
1. fibers (collagen, reticular fibers, elastic fibers)
| 2. amorphous ground substance (proteoglycans, plasma proteins, etc.)
60
function of proteoglycans
- resistance to compression
| - water retention
61
components of elastin fibers
- elastin protein
| - fibrilin protein (forming microfibrils)
62
elastin fibers found where and consequence of mutation
- skin, lungs, blood vessels*, etc.
| - can get aneurysms, stroke
63
Marfan syndrome charact
- fibrillin-1 gene mutation so problem in the microfibrils of elastin fibers
- ectopia lentis (displacement of eyes lenses)
