Structure&Function Flashcards
1
Q
- How much time does it take for a keratinocyte to mature and move from the basal layer to S.C.?
A
- 28 days
2
Q
- Once keratinocytes flatten and reach the granular layer, they lose nuclei and extrude all cellular contents except what two components?
A
- Keratin and filaggrin
3
Q
- Keratins make up type __ and type __ intermediate filaments?
A
- Type 1 and type 2 intermediate filaments
4
Q
- Type 1 keratins are: acidic or basic? Which keratins? What chromosome?
A
- Type 1 keratins are acidic, K9-20, Chr 17
5
Q
- Type 2 keratins are: acidic or basic? Which keratins? What chromosome?
A
- Type 2 keratins are basic, K1-8, Chr 12
6
Q
- Which layer of the skin contains keratohyaline granules? What do the keratohyaline granules contain?
A
- KH granules contain profilaggrin, keratin, loricrin. Results in formation of soft, flexible keratin.
7
Q
- What is filaggrin degraded to? What two functions do these products serve?
A
- Urocanic acid & pyrrolidone carboxylic acid. Hydrates S.C. and blocks UV radiation.
8
Q
- What are Odland bodies (lamellar granules)?
A
- 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.
9
Q
- What are the six desmosomal plaque proteins?
A
- 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)
10
Q
- What are gap junctions composed of and what do they do?
A
- GJ’s made up of connexons: A connexon is formed from six connexin molecules. Allow electrical and metabolic coupling among cells.
11
Q
- Name the corresponding connexins to the following gap junctions: GJB 2, GJB 3 and 4, GJB 6
A
- Connexin 26 (GJB 2);Connexin 31 + 30.3 (GJB 3 and 4); Connexin 30 (GJB 6)
12
Q
- The adhesion molecules cadherins are ______ -dependent.
A
- Ca2+.
13
Q
- Name some desmosomal cadherins.
A
- Desmoglein, desmocollins (membrane-bound); Plakoglobin, desmoplakins (cytoplasmic)
14
Q
- Melanocytes are derived from _____.
A
- Neural crest.
15
Q
- Each melanocyte interacts with approximately how many keratinocytes?
A
- 36 keratinocytes. = the epidermal melanin unit.
16
Q
- Why do melanocytes have a surrounding clear halo in the basal layer?
A
- Melanocytes lack tonofiliments, therefore cannot form desmosomal attachments with keratinocytes.
17
Q
- How do the melanosomes in darker skin compare to those in lighter skin?
A
- Melanosomes in dark skin are increased in size and number and are more singly dispersed. The have slow degradation.
18
Q
- What receptor/gene is the most important regulator of melanin production?
A
- MCR1 receptor (melanocortin 1) is most important regulation of melanin production. Redheads: loss-of-function mutation MCR1.
19
Q
- Where are Langerhans cells derived from? What is their main function? Main marker?
A
- Mesoderm/bone marrow derived. Function in antigen presentation. CD1a. Secrete IL-12.