Structure&Function Flashcards

1
Q
  1. How much time does it take for a keratinocyte to mature and move from the basal layer to S.C.?
A
  1. 28 days
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2
Q
  1. Once keratinocytes flatten and reach the granular layer, they lose nuclei and extrude all cellular contents except what two components?
A
  1. Keratin and filaggrin
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3
Q
  1. Keratins make up type __ and type __ intermediate filaments?
A
  1. Type 1 and type 2 intermediate filaments
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4
Q
  1. Type 1 keratins are: acidic or basic? Which keratins? What chromosome?
A
  1. Type 1 keratins are acidic, K9-20, Chr 17
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5
Q
  1. Type 2 keratins are: acidic or basic? Which keratins? What chromosome?
A
  1. Type 2 keratins are basic, K1-8, Chr 12
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6
Q
  1. Which layer of the skin contains keratohyaline granules? What do the keratohyaline granules contain?
A
  1. KH granules contain profilaggrin, keratin, loricrin. Results in formation of soft, flexible keratin.
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7
Q
  1. What is filaggrin degraded to? What two functions do these products serve?
A
  1. Urocanic acid & pyrrolidone carboxylic acid. Hydrates S.C. and blocks UV radiation.
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8
Q
  1. What are Odland bodies (lamellar granules)?
A
  1. Small, granular, membrane-bound vacuoles found in the cytoplasm of skin keratinocytes. They are derived from the Golgi apparatus and are associated with the storage and release of lipid precursors.
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9
Q
  1. What are the six desmosomal plaque proteins?
A
  1. Desmoplakins 1+2 (mediate attachement of keratins to plaque), desmocalmin (important for calcium regulation), Band 6 protein, plakoglobin (mediates attachment of keratins to plaque), and desmoyokin (associated with cell membrane)
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10
Q
  1. What are gap junctions composed of and what do they do?
A
  1. GJ’s made up of connexons: A connexon is formed from six connexin molecules. Allow electrical and metabolic coupling among cells.
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11
Q
  1. Name the corresponding connexins to the following gap junctions: GJB 2, GJB 3 and 4, GJB 6
A
  1. Connexin 26 (GJB 2);Connexin 31 + 30.3 (GJB 3 and 4); Connexin 30 (GJB 6)
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12
Q
  1. The adhesion molecules cadherins are ______ -dependent.
A
  1. Ca2+.
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13
Q
  1. Name some desmosomal cadherins.
A
  1. Desmoglein, desmocollins (membrane-bound); Plakoglobin, desmoplakins (cytoplasmic)
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14
Q
  1. Melanocytes are derived from _____.
A
  1. Neural crest.
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15
Q
  1. Each melanocyte interacts with approximately how many keratinocytes?
A
  1. 36 keratinocytes. = the epidermal melanin unit.
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16
Q
  1. Why do melanocytes have a surrounding clear halo in the basal layer?
A
  1. Melanocytes lack tonofiliments, therefore cannot form desmosomal attachments with keratinocytes.
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17
Q
  1. How do the melanosomes in darker skin compare to those in lighter skin?
A
  1. Melanosomes in dark skin are increased in size and number and are more singly dispersed. The have slow degradation.
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18
Q
  1. What receptor/gene is the most important regulator of melanin production?
A
  1. MCR1 receptor (melanocortin 1) is most important regulation of melanin production. Redheads: loss-of-function mutation MCR1.
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19
Q
  1. Where are Langerhans cells derived from? What is their main function? Main marker?
A
  1. Mesoderm/bone marrow derived. Function in antigen presentation. CD1a. Secrete IL-12.
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20
Q
  1. UV exposure increases or decreases Langerhans cell population?
A
  1. Decreases.
21
Q
  1. What type of cell is the Merkel cell? What is the stain to remember with this one?
A
  1. Neuroendocrine cell but also slow adapting type I mechanoreceptors. CK-20.
22
Q
  1. What virus is implicated in Merkel cell carcinoma?
A
  1. Polyomavirus.
23
Q
  1. What collagen makes up the lamina densa?
A
  1. Collagen IV.
24
Q
  1. The keratin intermediate filaments in the basal layer cell are made up of what keratins?
A
  1. K5, 14.
25
Q
  1. Anchoring fibrils are made up of what collagen?
A
  1. Type VII collagen.
26
Q
  1. What components traverse the lamina lucida?
A
  1. Laminin 5 (epiligrin), anchoring filaments, BPAg 2 (= BP180, = Collagen 17).
27
Q
  1. Name the components of the lamina densa? There are 6.
A
  1. Type IV collagen. Also have Laminin 5, Laminin 6, nidogen (entactin), fibulin, and perlican.
28
Q
  1. The epidermal appendages develop between weeks _____ of gestation? In what order?
A
  1. Weeks 18-24. Hair, sebaceous, eccrine, then apocrine.
29
Q
  1. How are eccrine glands innervated?
A
  1. Sympathetic cholinergic innervations. Through postganglionic C fiber production of acetylcholine.
30
Q
  1. Apocrine glands: what type of secretion? Contains? Innervation?
A
  1. Decapitation secretion. Consists of protein, carbs, lipids, ammonia, iron, sialomucin. Adrenergic.
31
Q
  1. Hair follicles develop during what weeks of gestation? Where on body first?
A
  1. 9-12 weeks. Head. Then Cephalad -> Caudal. Ectodysplasin A & noggin are essential for development.
32
Q
  1. What is the name for the area with widest diameter of the bulb?
A
  1. Line of Auber. Bulk of mitotic activity that gives rise to the hair and the IRS, ORS occurs below this level .
33
Q
  1. Name the three main phases of hair growth and how long they last?
A
  1. Anagen (3-5 yrs, active phase); Catagen (3wks, involution phase); Telogen (3-5mo, resting phase)
34
Q
  1. How does hair growth on the head differ from that on the body?
A
  1. Compared to scalp (2-6 years), most areas of the body have SHORTER Anagen (growing) phase and LONGER Telogen (resting) phase.4
35
Q
  1. Name the different eyelid glands and what type they are (apocrine or sebaceous)?
A
  1. Moll (apocrine), Meibomian (sebaceous, open into follicle), Zeiss (sebaceous, don’t open into follicle).
36
Q
  1. Name the sebaceous glands on the penis, areola, and lips.
A
  1. Fordyce (lips), Tyson (penis), Montgomery tubercles (areola)
37
Q
  1. What is the growth rate of fingernails? Toenails?
A
  1. Fingernails: 0.1mm/day (~3mm/month); Toenails: 0.03mm/day (~1mm/month).
38
Q
  1. Proximal fingernail matrix makes up what part of the nail plate? Distal matrix?
A
  1. Proximal matrix➠ dorsal plate, Distal matrix➠ ventral plate.
39
Q
  1. The dermis is made up of which collagens? Which are the “adult” and “fetal” collagens?
A
  1. Collagens I, III, V. Type I (85%) – adult; Type III (10%) – fetal; Type V (5%).
40
Q
  1. Collagen hydroxylation is dependent on what cofactor?
A
  1. Collagen hydroxylation: Prolyl and lysyl hydroxylase (require vitamin C).
41
Q
  1. Cross-linking of collagen molecules requires what cofactor?
A
  1. Cross-linking of collagen molecules: Catalyzed by lysyl oxidase (requires copper).
42
Q
  1. What stimulates versus inhibits collagen production?
A
  1. Stimulating collagen production: Ascorbic acid, TGF-B, Retinoic acid; Inhibiting collagen production: IL-1, Glucocorticoids, Interferon-γ, TNF-α, D-Penicillamine, Minoxidil.
43
Q
  1. What unique amino acids make up elastin?
A
  1. Elastin contains the unique AA’s Desmosine, Isodesmosine.
44
Q
  1. Describe the difference between oxytalin and elaunin microfibrils?
A
  1. Oxytalin fibers: run perpendicular; insert into BM from papillary dermis. Elaunin fibers: run parallel in reticular dermis; low elastin content.
45
Q
  1. Glycosaminoglycans and proteoglycans make up what?
A
  1. Ground substance. A proteoglycan is a macromolecule with core protein and attached GAGs.
46
Q
  1. Name two proteoglycans?
A
  1. Versican and perlecan.
47
Q
  1. Factor XIIIa and CD34 stain what type of cell? Which stains DFs? Which stains DFSP?
A
  1. Dendritic cells. 13a in DF; CD34 in DFSP.
48
Q
  1. Cross-linkage of involucrin into the S.C. envelope results from the activity of which enzyme?
A
  1. Epidermal transglutaminase.
49
Q
  1. Which cell am I? Neurosecretory granules are seen in the cytoplasm. The tumor cells stain with Neuron-specific enolase.
A
  1. Merkel cell/ Merkel cell carcinoma. Other stains: Neuron specific enolase (NSE), chromogranin, synaptophysin, VIP, CK20.