Intro to Derm- Development and structure of skin

Question 1

From which embryological elements does the skin arise? (Epidermis and dermis)

Answer 1

Epidermis from ectoderm and dermis from mesoderm (which comes in contact with inner surface of epidermis).

Question 2

What is the essential role of the mesoderm in the development of the skin?

Answer 2

Induces differentiation of epidermal structures, like the hair follicle.

Question 3

By which week is the epidermis formed?

Answer 3

week 4 (single layer of cuboidal cells)

Question 4

What is the periderm, what is its function and when does it develop

Answer 4

A secondary layer of squamous, non-keratinising cuboidal cells. It develops in week 5. It’s function is to produce a waxy white protective substance, vernix caseosa

Question 5

What is the stratum germintivum, when does it form and what does it do

Answer 5

It forms from week 11, it is the basal layer of cuboidal cells and proliferates to make 4 more layers of strata.

Question 6

What are the 5 stratum layers called.

Answer 6

corneum, lucidum, granulosum, spinousm and germinativum (come lets get some beers)

Question 7

Where is the stratum lucidum found

Answer 7

only on hands and feet

Question 8

What are melanocytes and where are they derived from?

Answer 8

melanin producing cells, derived from melanoblasts from the neural crest

Question 9

When do melanoblasts migrate and to where and to form what?

Answer 9

migrate dorsally to form dermis and epidermis

Question 10

What is the use of melanocyte stem cells and where are these found?

Answer 10

to replenish differentiated melanocytes, these are found in the hair follicle bulge.

Question 11

How is the synthesis of eumelanin regulated?

Answer 11

alphaMSH and ACTH activate MCR1 by antagonist, which induces the melanogenic cascada. This stimulates the synthesis of eumelanin.

Question 12

How does melanocortin 1 receptor (MC1R) work and how does it regulate melanins?

Answer 12

It is a G-coupled receptor, regulated by alphaMSH and ACTH. Its activation results in the melaogenic cascade which ending the production of melanins.

Question 13

How does POMC regulate melanin production?

Answer 13

POMC is the hormone which regulate the repase of alphaMSH and ACTH

Question 14

What does agouti signaling protein (ASP) do?

Answer 14

reserves the effects of ACTHand alphaMSH, to cause the production go pheomelanin.

Question 15

How does UV exposure regulate melanocyte/melanin content?

Answer 15

Increases melanin production by increasing the expression of transcription factor MITF (and downstrain melanogenic products like TYR and TRP1)

Question 16

What layers is the dermis divided into?

Answer 16

papillary and reticular

Question 17

Which cells make up the epidermis?

Answer 17

keratinocytes, in different stages of differentiation

Question 18

What differentiates the different layers of the basal layer?

Answer 18

Only place where cell division takes place

Question 19

What is special about the stratum corneum?

Answer 19

It’s cells have no nuclei or organelles

Question 20

How long does it take cells to go from the basal layer to the surface more or less? When does this accelerate?

Answer 20

30 days, accelerates with skin disease (eg psoriasis)

Question 21

What forms the cytoskeleton of keratinocytes?

Answer 21

actin and tubular microtubules and intermediate filaments made of keratins

Question 22

What are desmosomes? What is their function?

Answer 22

adhesion complex in epidermis, which allows cells to withstand damage and anchor keratin intermediate filaments to cell membrane and bridge adjacent keratinocytes

Question 23

What are adherences junctions?

Answer 23

transmembrane structures and actin skeleton

Question 24

What are gap junctions?

Answer 24

intercellular channels which form direct connections between the cytoplasms of adjacent keratinocytes

Question 25

What is the function of melanocytes?

Answer 25

to distribute melanin pigment to keratinocytes

Question 26

What is the function of langerhans cells?

Answer 26

immune response-APCs

Question 27

What is the function of Merkel cells?

Answer 27

mechanosensory receptors

Question 28

What proteins and glycoproteins make up the basement membrane of the skin?

Answer 28

collagens, laminin and integrins

Question 29

What is the role of the basement membrane?

Answer 29

cell adhesion and cell migration

Question 30

What two layers can the dermis be divided into? Which layer has less vascular supply? Which one is most superficial? Which one has the most connective tissue? Which one is bigger?

Answer 30

papillary and reticular. the papillary dermis is most superficial has less connective tissue and more vascular supply. The largest layer is the reticular dermis.

Question 31

Which proteins are present in the dermis? Which one is predominant?

Answer 31

collagen and elastic fibres 8elastin, fibrillin)

Question 32

What are the functions of the glycoproteins in the dermis?

Answer 32

to facilitate cell adhesion and motility (eg fibulin)

Question 33

What makes up the ground substance?

Answer 33

glycosaminoglycan and proteoglycan

Question 34

What is the function of fibroblasts?

Answer 34

to generate connective tissue and repair tissue from injury.