Structure and function of skin

Question 1

what embryological layer forms epidermis

Answer 1

ectoderm - to make periderm

Question 2

what embryological layer forms dermis

Answer 2

mesoderm

Question 3

what forms melanocytes

Answer 3

neural crest

Question 4

what are Blaschko’s lines

Answer 4

pattern of developmental growth of skin cells. it does not follow vessels, nerves or lymphatics

Question 5

true/false - epidermis is stratified columnar epithelia

Answer 5

false - it is stratified squamous epithelia

Question 6

what is the primary cell type of the epidermis

Answer 6

keratinocyte

Question 7

name 2 examples of where control of cell turnover is lost in the epidermis

Answer 7

skin cancer

psoriasis

Question 8

the basal layer is how many layers thick and is made up of what type of stem cells

Answer 8

1 layer thick

cuboidal stem cells

Question 9

what intercellular junctions do cells in the prickle cell layer contain

Answer 9

desmosomes

Question 10

what is the keratin layer made up of

Answer 10

non-nucleated remnants of keratinocytes
keratin
filaggrin

Question 11

how is the keratin layer waterproof

Answer 11

filaggrin binds water
tight intercellular junctions limit diffusion
intercellular lipid bilayer and lipid content repels water

Question 12

what do keratohyalin granules contain and where are they found

Answer 12

keratin and filaggrin

granular layer

Question 13

what do lamellar bodies contain/secrete

Answer 13

lipids and filaggrin

Question 14

how do melanocytes create colour in the skin?

Answer 14

contain melanosomes that travel up dentrites to release melanin to keratinocytes

Question 15

what is the compound converted to melanin by melanocytes?

Answer 15

tyrosine

Question 16

how does melanin protect basal cells

Answer 16

blocks passage of UV radiation from light to basal cells to prevent DNA damage

Question 17

where are langerhans cells found and what is their function

Answer 17

prickle cell layer, dermis and lymph nodes

act as APC, and circulates to lymph node

Question 18

where are merkel cells found and what do they do

Answer 18

found between keratinocytes and nerve fibres

mechanoreceptors for touch sensation

Question 19

a hair follicle contains a d___ p___ and what gland?

Answer 19

dermal papilla

sebaceous gland

Question 20

what determines hair colour in the follicle

Answer 20

melanocyte above dermal papilla

Question 21

describe anagen

Answer 21

growth phase that majority of hairs are in

Question 22

describe catagen

Answer 22

involuting phase where growth stops and hair clubs ready to fall out

Question 23

describe telogen

Answer 23

resting phase where hair falls out

Question 24

what is the function of the cuticle

Answer 24

protective barrier for nail to prevent infection

Question 25

describe nail growth

Answer 25

nail matrix is made up of stem cells. these replicate and push out keratinocytes that flatten, lose nucleus and become elongated to form shape of nail

Question 26

what is the dermo-epidermal junction and what is its function

Answer 26

semi permeable barrier between dermis and epidermis | barrier and support/adhesion for basal cells

Question 27

two types of dermis

Answer 27

papillary dermis | reticular dermis

Question 28

what is the dermis made up of

Answer 28

ground substance collagen and elastin fibroblasts (main cell), langerhans, mast cells, macrophages, lymphocytes muscles, blood vessels, lymphatics, nerves

Question 29

deep plexuses run horizontally in the reticular/papillary dermis and superficial plexuses run horizontally in the reticular/papillary epidermis

Answer 29

reticular | papillary

Question 30

describe the function of lymphatic vessels of the dermis

Answer 30

drains debris, excess interstitial fluid and plasma | allows travel of langerhan cells and lymphocytes for immune surveillance

Question 31

pacinian corpuscles sense?

Answer 31

pressure

Question 32

meissners corpuscles sense?

Answer 32

vibration

Question 33

function of sebaceous gland?

Answer 33

lubricates hair haft, skin and antimicrobial

Question 34

what is the arrector pili muscle controlled by?

Answer 34

ANS

Question 35

what hormones alter hair growth?

Answer 35

androgens and thyroxine

Question 36

where are sebaceous glands largest and when are they most active

Answer 36

head, face, shoulders and upper chest | during puberty as they are hormone sensitive

Question 37

where are apocrine glands found

Answer 37

axialla and perineum

Question 38

where are eccrine glands found, what is their function and control?

Answer 38

everywhere but mostly hands, feet, hair thermoregulation - cools by evaporation control by sympathetic part of ANS

Question 39

functions of the skin?

Answer 39

``` barrier metabolism and synthesis communication immunity sensory thermoregulation ```

Question 40

how does the skin synthesise vitamin D

Answer 40

converts 7-dehydrocholesterol to vitamin D3 by UVB

Question 41

What hormone is synthesised from thyroxine by the skin

Answer 41

T3