Structure and Function

Question 1

what are the two layers of the skin

Answer 1

epidermis and dermis

Question 2

what cells make up the epidermis

Answer 2

stratified squamous cells

Question 3

where is the epidermis derived from

Answer 3

the ectoderm

Question 4

what cells make up 95% of the epidermis

Answer 4

keratinocytes

Question 5

what are the four defined layers of the epidermis

Answer 5

keratin
granular
prickle cell
basal

Question 6

what is the dermis derived from

Answer 6

the mesoderm

Question 7

What are the 4 types of epidermal cell

Answer 7

keratinocytes
melanocytes
Langerhans cells
Merkel’s cells

Question 8

what are melanocytes and where do they originate from

Answer 8

pigment producing cells originating from the neural crest

Question 9

what 3 layers are formed at 4 weeks of foetal skin development

Answer 9

Periderm
Basal layer
Dermis

Question 10

by 16 weeks what are the 5 layers of skin formed

Answer 10

keratin layer 
granular layer 
prickle cell layer 
basal layer 
dermis

Question 11

at how many weeks do hair, melanocytes and appendages form

Answer 11

26 weeks

Question 12

what pattern does the development of skin follow

Answer 12

Blashko’s lines

Question 13

what factors regulate epidermal turn over

Answer 13

growth factors
cell death
hormones

(loss of this control is seen in skin cancer and psoriasis)

Question 14

How many days does it take for the epidermis to regenerate (from bottom to top)

Answer 14

28 days

Question 15

which layer is one cell thick, has small cuboidal shaped cells, contains intermediate filaments and is highly metabolically active

Answer 15

basal layer

Question 16

the prickle cell layer is thinner in psoriasis true/false

Answer 16

false

its thicker

Question 17

what layer contains island bodies (secretory cells)

Answer 17

granular

Question 18

what does the keratin layer consist of

Answer 18

corneocytes (overlapping, non-nucleated cell remnants, differentiated keratinocytes)

Question 19

what other than corneocytes does the keratin layer contain

Answer 19

cornfield envelope
keratin and filaggrin
lamellar granules (release lipids)

Question 20

where do melanocytes originate

Answer 20

neural crest (migrate to the epidermis in the first 3 month of development)

Question 21

where are melanocytes found

Answer 21

the basal layer

Question 22

what do melanocytes do

Answer 22

pigment producing dendritic cells, convert tyrosine to melanin pigment

melanin granules are transferred to adjacent keratinocytes via dendrites

form a protective cap over DNA in the basal cells to protect from UV light and hormones

Question 23

what colour is Eumelanin

Answer 23

brown or black

Question 24

what colour is Phaemelanin

Answer 24

red or yellow

Question 25

where do langerhans cells originate

Answer 25

bone marrow

Question 26

what do langerhans cells do

Answer 26

antigen presenting cells

Question 27

where are Merkel cells found

Answer 27

basal layer, on the ends of nerve fibres, direct extension of the brain

Question 28

what do merkels cells do

Answer 28

mechanoreceptors (respond to mechanical stimuli)

Question 29

what is vitiligo

Answer 29

a skin condition involving hypo pigmentation of the skin due to the melanocytes being attacked by T cells

Question 30

what is Nelson's syndrome

Answer 30

where melanin stimulating hormone is produced in excess by the pituitary gland causing bronzing of the skin

Question 31

what are the three stages of hair growth

Answer 31

Anagen -growing Catagen -involuting Telogen -resting

Question 32

at what rate do nails grow

Answer 32

0.1mm per day

Question 33

what is the demo-epidermal junction and what are its functions

Answer 33

the interface between the dermis and the epidermis provides anchorage, support, and adhesion as well as being a semi permeable membrane acting as a barrier and a filter

Question 34

What are the three layers of the demo-epidermal junction

Answer 34

``` Lamina Lucida (top) Lamina Densa (middle) Sub-lamina Densa (bottom) ```

Question 35

failure of function of the demo-epidermal junction leads to

Answer 35

fragile skin | fluid filled blisters

Question 36

what is the dermis made up of

Answer 36

``` ground substance (gives structure) collagen elastin immune cells blood vessels lymphatics nerves hair follicles ```

Question 37

the blood supply to the skin is greater than metabolic need true/false

Answer 37

true

Question 38

what is an angioma

Answer 38

a benign overgrowth of blood vessels

Question 39

what do pancain nerves do

Answer 39

sense pressure

Question 40

what do meissners nerves do

Answer 40

sense vibration

Question 41

what causes pigmentation of hair

Answer 41

melanocytes above the papilla

Question 42

what do sebaceous skin glands produce and whats their function

Answer 42

produce oily, waxy sebum, hormone sensitive glands which control moisture and protect from fungal infections

Question 43

what do apocrine glands produce and whats their function

Answer 43

sweat glands which produce odour due to bacterial decomposition, linked to hair follicles

Question 44

what do eccrine produce whats there function

Answer 44

sweat glands occurring everywhere not attached to hair follicle