Physiology of Skin Flashcards
what is the outer layer of the skin called
epidermis
what cell type is the epidermis made up of and where is it derived from
stratified squamous epithelium
derived from ectoderm
where is the dermis located
beneath the epidermis
what cell types make up the dermis and where is it derived from
connective tissue
derived from mesoderm
where are melanocytes derived from
neural crest
at 16 weeks development what layer of the skin have formed
all 4 layers of epidermis and dermis
at 26 weeks development what layers of the skin have formed
completely formed with hair follicle present
from superficial to deep list the components of the skin
epidermis appendages - inc hair, nails, glands and mucosae dermo-epidermal junction dermis sub-cutis - mainly fat
what cell type is the main constituent of the epidermis
keratinocytes
list some other cell types in the epidermis other than keratinocytes
langerhans cells, merkel cells, melanocytes
list the 4 layers of the epidermis from superficial to deep
keratin layer
granular layer
prickle cell layer
basal layer
where do keratinocytes travel to in the epidermis
from the basal layer (basement membrane) upwards allowing for continuous turnover
describe the basal cell layer
one cell thick
made up of intermediate filaments
highly metabolically active
describe the prickle cell layer
larger polyhedral cells
contain desmosome connections
intermediate filaments of the basal layer connect to desmosomes
describe the granular layer
several layers of flat cells
granules contain filaggrin and proteins
increased lipid content
where is the cell nuclei lost in the epidermis
granular layer before keratin layer
describe the keratin layer
contains corneocytes - terminal keratinocytes lacking cell nucleus, cell remnants
tight waterproof barrier contain keratin and filaggrin
where are melanocytes located in the epidermis
basal layer and above
what is the function of melanocytes
convert tyrosine into melanin pigment
what colours are eumelanin and phaeomelanin and what people are the found in
eumelanin - brown/black found in dark skin
phaeomelanin - red/yellow found in light skin
what is vitiligo
autoimmune destruction causing loss of melanocytes
what is albinism
genetic cause of partial loss of pigment production
where do langerhans cells originate from
bone marrow
where are langerhans cells located
prickle cell layer but also dermis and lymph nodes
what is the function of Langerhans cells
immune function, APCs that circulate antigen towards lymph nodes
where are Merkel cells located
in basal layer
what is the function of merkel cells
mechanoreceptors used for light touch sensations
what makes up the pilo-sebaceous unit
hair shaft, hair follicle, sebaceous gland and erector pili muscle
list the three phases of hair growth
anagen - growing
catagen - involuting (curving inwards)
telogen - resting
describe hirsutism
male pattern hair growth in females, eg on chin and chest
describe virilisation
having male characteristics eg deepening of voice, acne
what causes hirsutism and virilisation
excess androgen production
what are nails
type of specialised keratins
describe the dermo-epidermal junction
interface between epidermis and dermis
what is the function of the DEJ
provides support, anchorage, growth and adhesion for the skin
name a disorder of the DEJ
bullous pemphigoid
list the layer of the DEJ from the basal layer to the dermis
lamina lucida
lamina densa
sub-lamina densa zone
what is the dermis made up of
connective tissue, collagen and elastin
name the cell types within the dermis
macrophages, mast cells, fibroblasts, Langerhan cells
what type of nerve supplies the skin
somatic sensory with free nerve endings
name the pressure receptor within the skin
Pacinian receptors
name the vibration receptor within the skin
Meissners
list a disorder of nerve tissue affecting the skin
neurofibromatosis
list the three types of glands within the skin
sebaceous
apocrine
eccrine
where are sebaceous glands located
widely distributed, especially in the chest and face
sebaceous glands are functioning from birth true/false
false - hormone sensitive glands therefore activated after puberty
what is the function of sebaceous glands
control moisture loss and protection from fungal infection
name a disorder of sebaceous gland
acne
where are apocrine glands found
axillae and perineum
apocrine glands are androgen dependent true/false
true
what is the function of apocrine glands
produces oily fluid which has odour after bacterial decomposition
where are the eccrine glands located
palms, soles and axillae
what is the function of the eccrine glands
cooling by evaporation, moistens palms and soles to aid grip
out of all three glands which one is a normal sweat gland
eccrine gland
