Physiology of Skin

Question 1

what is the outer layer of the skin called

Answer 1

epidermis

Question 2

what cell type is the epidermis made up of and where is it derived from

Answer 2

stratified squamous epithelium

derived from ectoderm

Question 3

where is the dermis located

Answer 3

beneath the epidermis

Question 4

what cell types make up the dermis and where is it derived from

Answer 4

connective tissue

derived from mesoderm

Question 5

where are melanocytes derived from

Answer 5

neural crest

Question 6

at 16 weeks development what layer of the skin have formed

Answer 6

all 4 layers of epidermis and dermis

Question 7

at 26 weeks development what layers of the skin have formed

Answer 7

completely formed with hair follicle present

Question 8

from superficial to deep list the components of the skin

Answer 8

epidermis 
appendages - inc hair, nails, glands and mucosae 
dermo-epidermal junction 
dermis 
sub-cutis - mainly fat

Question 9

what cell type is the main constituent of the epidermis

Answer 9

keratinocytes

Question 10

list some other cell types in the epidermis other than keratinocytes

Answer 10

langerhans cells, merkel cells, melanocytes

Question 11

list the 4 layers of the epidermis from superficial to deep

Answer 11

keratin layer
granular layer
prickle cell layer
basal layer

Question 12

where do keratinocytes travel to in the epidermis

Answer 12

from the basal layer (basement membrane) upwards allowing for continuous turnover

Question 13

describe the basal cell layer

Answer 13

one cell thick
made up of intermediate filaments
highly metabolically active

Question 14

describe the prickle cell layer

Answer 14

larger polyhedral cells
contain desmosome connections
intermediate filaments of the basal layer connect to desmosomes

Question 15

describe the granular layer

Answer 15

several layers of flat cells
granules contain filaggrin and proteins
increased lipid content

Question 16

where is the cell nuclei lost in the epidermis

Answer 16

granular layer before keratin layer

Question 17

describe the keratin layer

Answer 17

contains corneocytes - terminal keratinocytes lacking cell nucleus, cell remnants
tight waterproof barrier contain keratin and filaggrin

Question 18

where are melanocytes located in the epidermis

Answer 18

basal layer and above

Question 19

what is the function of melanocytes

Answer 19

convert tyrosine into melanin pigment

Question 20

what colours are eumelanin and phaeomelanin and what people are the found in

Answer 20

eumelanin - brown/black found in dark skin

phaeomelanin - red/yellow found in light skin

Question 21

what is vitiligo

Answer 21

autoimmune destruction causing loss of melanocytes

Question 22

what is albinism

Answer 22

genetic cause of partial loss of pigment production

Question 23

where do langerhans cells originate from

Answer 23

bone marrow

Question 24

where are langerhans cells located

Answer 24

prickle cell layer but also dermis and lymph nodes

Question 25

what is the function of Langerhans cells

Answer 25

immune function, APCs that circulate antigen towards lymph nodes

Question 26

where are Merkel cells located

Answer 26

in basal layer

Question 27

what is the function of merkel cells

Answer 27

mechanoreceptors used for light touch sensations

Question 28

what makes up the pilo-sebaceous unit

Answer 28

hair shaft, hair follicle, sebaceous gland and erector pili muscle

Question 29

list the three phases of hair growth

Answer 29

anagen - growing catagen - involuting (curving inwards) telogen - resting

Question 30

describe hirsutism

Answer 30

male pattern hair growth in females, eg on chin and chest

Question 31

describe virilisation

Answer 31

having male characteristics eg deepening of voice, acne

Question 32

what causes hirsutism and virilisation

Answer 32

excess androgen production

Question 33

what are nails

Answer 33

type of specialised keratins

Question 34

describe the dermo-epidermal junction

Answer 34

interface between epidermis and dermis

Question 35

what is the function of the DEJ

Answer 35

provides support, anchorage, growth and adhesion for the skin

Question 36

name a disorder of the DEJ

Answer 36

bullous pemphigoid

Question 37

list the layer of the DEJ from the basal layer to the dermis

Answer 37

lamina lucida lamina densa sub-lamina densa zone

Question 38

what is the dermis made up of

Answer 38

connective tissue, collagen and elastin

Question 39

name the cell types within the dermis

Answer 39

macrophages, mast cells, fibroblasts, Langerhan cells

Question 40

what type of nerve supplies the skin

Answer 40

somatic sensory with free nerve endings

Question 41

name the pressure receptor within the skin

Answer 41

Pacinian receptors

Question 42

name the vibration receptor within the skin

Answer 42

Meissners

Question 43

list a disorder of nerve tissue affecting the skin

Answer 43

neurofibromatosis

Question 44

list the three types of glands within the skin

Answer 44

sebaceous apocrine eccrine

Question 45

where are sebaceous glands located

Answer 45

widely distributed, especially in the chest and face

Question 46

sebaceous glands are functioning from birth true/false

Answer 46

false - hormone sensitive glands therefore activated after puberty

Question 47

what is the function of sebaceous glands

Answer 47

control moisture loss and protection from fungal infection

Question 48

name a disorder of sebaceous gland

Answer 48

acne

Question 49

where are apocrine glands found

Answer 49

axillae and perineum

Question 50

apocrine glands are androgen dependent true/false

Answer 50

true

Question 51

what is the function of apocrine glands

Answer 51

produces oily fluid which has odour after bacterial decomposition

Question 52

where are the eccrine glands located

Answer 52

palms, soles and axillae

Question 53

what is the function of the eccrine glands

Answer 53

cooling by evaporation, moistens palms and soles to aid grip

Question 54

out of all three glands which one is a normal sweat gland

Answer 54

eccrine gland