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Flashcards in Skin Structure and Function Deck (60)
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1

What are the 2 main layers of skin?

The epidermis (outer) and the dermis

2

Which germ layer is the epidermis derived from?

ectoderm

3

How does the epidermis form in the fetus?

Ectoderm cells form a single layer periderm which gradually increase in layers and before birth the periderm cells are cast off

4

What germ layer is the dermis derived from?

mesoderm

5

What are melanocytes derived from?

the neural crest

6

What are the 6 layers in skin?

Keratin layer
Granular layer
Prickle cell layer
basal layer
dermis
sub-cutis

7

what are blaschkos lines?

developmental growth patterns of skin, which don't follow vessels, nerves or lympathics

8

What does the skin consist of?

epidermis; appendages (hair, nails, glands, mucosae) ; dermo-epidermal junction; dermis and the sub-cutis

9

What does the basal layer do?

Divides in order to replenish the upper layers

10

How does the prickle cell layer become the granular layer?

It differentiates and produces lots of protein (granular- lots of proteins)

11

How does the granular layer becoem the keratin layer?

Releases protein in order to become flat

12

What type of epithelium is the epidermis

stratified squamous epithelium

13

What are the majority of the cells found in the epidermis?

Keratinocytes which contain structural keratins

14

What other cells are found within the epidermis?

Melanocytes; langerhan cells and merkel cells

15

How is epidermal turnover regulated?

growth factors; cell death and hormones

16

How long does it take for a keratinocytes to migrates from the basmement membrane to the top?

28 days

17

Describe the basal layer

usually one cell thick
small cuboidal
lots of intermediate filaments (keratin)
highly metabolically active

18

Describe the prickle cell layer

larger polyhedral cells
lots of desmosomes
intermediate filaments connect to desmosomes
(named after prickly pear appearance)

19

Describe the granular layer

2-3 layers of flatter cells
large keratohyalin granules- contain structural filaggrin and involucrin proteins
odland bodies ( lamellar bodies)
high lipid content
origin of "cornified envelope"
cell nuclei lost

20

What is the cornified envelope?

A layer of ceramides which become covalently bonded to an envelope of structural proteins. This replaces the cell membrane during a process called cornification in which live keratinocytes become non-living corneocytes. The complex surrounds the cells and contributes to the barrier function of the skin.

21

Describe the keratin layer

Made up of the corneocytes- overlapping non-nucleated cell remnants
insoluble cornified envelope
80% keratin and filagrin
lamellar granuels release lipid
TIGHT WATRETPROOF BARRIER

22

What are melanocytes?

pigment producing dendritic cells

23

Where are melanocytes found?

in the basal layer and above

24

What happens in the melanosomes?

tyrosine is converted to melanin pigment

25

What happens to full melanosomes (melanin granules)?

they are transferred to adjacent keratinocyte via dendrites

26

What is the function of melanin granules?

form a protective cap over nucleus as they absorb light and prevent UV ray messing with the DNA in basal cells

27

What is vitiligo?

an autoimmune disease where there is loss of melanocytes

28

What is the origin of langerhan cells?

mesenchymal origin (bone marrow)

29

Where are Langerhan cells found in the skin?

prickle cell level in the epidermis and in dermis (also in lymph nodes)

30

What is the function of langerhan cells?

APCs - pick up Ag in skin and circulate to lymph nodes via lymphatics