Physiology Flashcards
what is the largest organ in the body?
the skin
what are the core layers of the skin?
epidermis appendages derma-epidermal junction dermis sub-cutis layer
what are the layers of the epidermis
keratin layer
granular layer
prickle cell layer
basal layer
what epithelium is the epidermis composed of?
stratified squamous epithelium
another name for the keratin layer
stratum corneum
what is the keratin layer made up of?
corneocytes (overlapping, non-nucleated remnants) and lamellar granules containing lipids and keratinocytes
function of the keratin layer
waterproof barrier
what does the granular layer consist of?
2-3 layers of flatten cells with keratohyalin granules that contain filaggrin and involucres protein
role of the granular layer
envelope that protects corneocytes
what does the prickle layer consist of?
larger polyhedral cells with lots of desmosomes connected to intermediate filaments
what does the basal layer consist of?
cuboidal cells with intermediate filaments
high metabolic rate
melanocytes are found here and transfer melanin via dendritic processes
describe epidermal turnover
keratinocytes migrate from the basement membrane to the stratum corneum over 28 days
what is epidermal turnover regulated by?
growth factors
cell death
hormones
when is epidermal control lost?
cancer
psoriasis (immature epidermis)
other cells present in the epidermis
melanocytes
Langerhans cells
Merkel cells
describe melanocytes
pigment-producing dendritic cells that contain melanosomes that transfer to keratinocytes via dendrites
role of melanocytes
convert tyrosine to melanin (eumelanin- brown and phaeomelanin- yellow/red)
what does melanin in melanocytes do?
absorbs sunlight forming a protective cap over the nucleus