Basic Structure and Function2

Question 1

1. How much time does it take for a keratinocyte to mature and move from the basal layer to S.C.?

Answer 1

1. 28 days

Question 2

2. Once keratinocytes flatten and reach the granular layer, they lose nuclei and extrude all cellular contents except what two components?

Answer 2

2. Keratin and filaggrin

Question 3

3. Keratins make up type __ and type __ intermediate filaments?

Answer 3

3. Type 1 and type 2 intermediate filaments

Question 4

4. Type 1 keratins are: acidic or basic? Which keratins? What chromosome?

Answer 4

4. Type 1 keratins are acidic, K9-20, Chr 17

Question 5

5. Type 2 keratins are: acidic or basic? Which keratins? What chromosome?

Answer 5

5. Type 2 keratins are basic, K1-8, Chr 12

Question 6

6. Which layer of the skin contains keratohyaline granules? What do the keratohyaline granules contain?

Answer 6

6. KH granules contain profilaggrin, keratin, loricrin. Results in formation of soft, flexible keratin.

Question 7

7. What is filaggrin degraded to? What two functions do these products serve?

Answer 7

7. Urocanic acid & pyrrolidone carboxylic acid. Hydrates S.C. and blocks UV radiation.

Question 8

8. What are Odland bodies (lamellar granules)?

Answer 8

8. 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.

Question 9

9. What are the six desmosomal plaque proteins?

Answer 9

9. 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)

Question 10

10. What are gap junctions composed of and what do they do?

Answer 10

10. GJ?s made up of connexons: A connexon is formed from six connexin molecules. Allow electrical and metabolic coupling among cells.

Question 11

11. Name the corresponding connexins to the following gap junctions: GJB 2, GJB 3 and 4, GJB 6

Answer 11

11. Connexin 26 (GJB 2);Connexin 31 + 30.3 (GJB 3 and 4); Connexin 30 (GJB 6)

Question 12

12. The adhesion molecules cadherins are ______ -dependent.

Answer 12

12. Ca2+.

Question 13

13. Name some desmosomal cadherins.

Answer 13

13. Desmoglein, desmocollins (membrane-bound); Plakoglobin, desmoplakins (cytoplasmic)

Question 14

14. Melanocytes are derived from _____.

Answer 14

14. Neural crest.

Question 15

15. Each melanocyte interacts with approximately how many keratinocytes?

Answer 15

15. 36 keratinocytes. = the epidermal melanin unit.

Question 16

16. Why do melanocytes have a surrounding clear halo in the basal layer?

Answer 16

16. Melanocytes lack tonofiliments, therefore cannot form desmosomal attachments with keratinocytes.

Question 17

17. How do the melanosomes in darker skin compare to those in lighter skin?

Answer 17

17. Melanosomes in dark skin are increased in size and number and are more singly dispersed. The have slow degradation.

Question 18

18. What receptor/gene is the most important regulator of melanin production?

Answer 18

18. MCR1 receptor (melanocortin 1) is most important regulation of melanin production. Redheads: loss-of-function mutation MCR1.

Question 19

19. Where are Langerhans cells derived from? What is their main function? Main marker?

Answer 19

19. Mesoderm/bone marrow derived. Function in antigen presentation. CD1a. Secrete IL-12.

Question 20

20. UV exposure increases or decreases Langerhans cell population?

Answer 20

20. Decreases.

Question 21

21. What type of cell is the Merkel cell? What is the stain to remember with this one?

Answer 21

21. Neuroendocrine cell but also slow adapting type I mechanoreceptors. CK-20.

Question 22

22. What virus is implicated in Merkel cell carcinoma?

Answer 22

22. Polyomavirus.

Question 23

23. What collagen makes up the lamina densa?

Answer 23

23. Collagen IV.

Question 24

24. The keratin intermediate filaments in the basal layer cell are made up of what keratins?

Answer 24

24. K5, 14.

Question 25

25. Anchoring fibrils are made up of what collagen?

Answer 25

25. Type VII collagen.

Question 26

26. What components traverse the lamina lucida?

Answer 26

26. Laminin 5 (epiligrin), anchoring filaments, BPAg 2 (= BP180, = Collagen 17).

Question 27

27. Name the components of the lamina densa? There are 6.

Answer 27

27. Type IV collagen. Also have Laminin 5, Laminin 6, nidogen (entactin), fibulin, and perlican.

Question 28

28. The epidermal appendages develop between weeks _____ of gestation? In what order?

Answer 28

28. Weeks 18-24. Hair, sebaceous, eccrine, then apocrine.

Question 29

29. How are eccrine glands innervated?

Answer 29

29. Sympathetic cholinergic innervations. Through postganglionic C fiber production of acetylcholine.

Question 30

30. Apocrine glands: what type of secretion? Contains? Innervation?

Answer 30

30. Decapitation secretion. Consists of protein, carbs, lipids, ammonia, iron, sialomucin. Adrenergic.

Question 31

31. Hair follicles develop during what weeks of gestation? Where on body first?

Answer 31

31. 9-12 weeks. Head. Then Cephalad -> Caudal. Ectodysplasin A & noggin are essential for development.

Question 32

32. What is the name for the area with widest diameter of the bulb?

Answer 32

32. Line of Auber. Bulk of mitotic activity that gives rise to the hair and the IRS, ORS occurs below this level .

Question 33

33. Name the three main phases of hair growth and how long they last?

Answer 33

33. Anagen (3-5 yrs, active phase); Catagen (3wks, involution phase); Telogen (3-5mo, resting phase)

Question 34

34. How does hair growth on the head differ from that on the body?

Answer 34

34. Compared to scalp (2-6 years), most areas of the body have SHORTER Anagen (growing) phase and LONGER Telogen (resting) phase.

Question 35

35. Name the different eyelid glands and what type they are (apocrine or sebaceous)?

Answer 35

35. Moll (apocrine), Meibomian (sebaceous, open into follicle), Zeiss (sebaceous, don?t open into follicle).

Question 36

36. Name the sebaceous glands on the penis, areola, and lips.

Answer 36

36. Fordyce (lips), Tyson (penis), Montgomery tubercles (areola)

Question 37

37. What is the growth rate of fingernails? Toenails?

Answer 37

37. Fingernails: 0.1mm/day (~3mm/month); Toenails: 0.03mm/day (~1mm/month).

Question 38

38. Proximal fingernail matrix makes up what part of the nail plate? Distal matrix?

Answer 38

38. Proximal matrix? dorsal plate, Distal matrix? ventral plate.

Question 39

39. The dermis is made up of which collagens? Which are the ?adult? and ?fetal? collagens?

Answer 39

39. Collagens I, III, V. Type I (85%) ? adult; Type III (10%) ? fetal; Type V (5%).

Question 40

40. Collagen hydroxylation is dependent on what cofactor?

Answer 40

40. Collagen hydroxylation: Prolyl and lysyl hydroxylase (require vitamin C).

Question 41

41. Cross-linking of collagen molecules requires what cofactor?

Answer 41

41. Cross-linking of collagen molecules: Catalyzed by lysyl oxidase (requires copper).

Question 42

42. What stimulates versus inhibits collagen production?

Answer 42

42. Stimulating collagen production: Ascorbic acid, TGF-B, Retinoic acid; Inhibiting collagen production: IL-1, Glucocorticoids, Interferon-?, TNF-à, D-Penicillamine, Minoxidil.

Question 43

43. What unique amino acids make up elastin?

Answer 43

43. Elastin contains the unique AA?s Desmosine, Isodesmosine.

Question 44

44. Describe the difference between oxytalin and elaunin microfibrils?

Answer 44

44. Oxytalin fibers: run perpendicular; insert into BM from papillary dermis. Elaunin fibers: run parallel in reticular dermis; low elastin content.

Question 45

45. Glycosaminoglycans and proteoglycans make up what?

Answer 45

45. Ground substance. A proteoglycan is a macromolecule with core protein and attached GAGs.

Question 46

46. Name two proteoglycans?

Answer 46

46. Versican and perlecan.

Question 47

47. Factor XIIIa and CD34 stain what type of cell? Which stains DFs? Which stains DFSP?

Answer 47

47. Dendritic cells. 13a in DF; CD34 in DFSP.

Question 48

48. Cross-linkage of involucrin into the S.C. envelope results from the activity of which enzyme?

Answer 48

48. Epidermal transglutaminase.

Question 49

49. Which cell am I? Neurosecretory granules are seen in the cytoplasm. The tumor cells stain with Neuron-specific enolase.

Answer 49

49. Merkel cell/ Merkel cell carcinoma. Other stains: Neuron specific enolase (NSE), chromogranin, synaptophysin, VIP, CK20.