Chapter 5: The Epidermis
stratum basale
deepest epidermal layer made of a single row of cells that undergo rapid cell division
Merkel cells
function as touch receptors in association with sensory nerve endings located in stratum basale
Dendratic cells
in the stratum spinosum, are phagocytes that protect the skin and deeper tissues from pathogens.
Two structural features of keratinocytes that make epidermis stronger
manufacture keratin and linked together by demosomes
other cells of the epidermis
melanocytes, Dendratic (langerhans) cells, merkel cells
Kerationcyte life cycle
migration from the deepest strata to the stratum corneum takes a cell between 40-50 days to complete.
stradum lucidum
narrow layer of clear dead keratinocytes found only in thick skin.
Melanocytes
produce melanin found in stratum basale
layers of epidermis
stratum basale, stratum spinosum, stratum granulosum, stratum lucidum, stratum corneum
stratum corneum
the most superficial layer of the epidermis consisting of dead cells that are sloughed off as the desmosomes are lost
Keratinocytes
The most abundant epidermal cells, they function mainly to produce keratin.
stratum granulosum
cells begin to die and become filled with keratin bundles or lipid-based substances
stratum spinosum
thickest layer, sits on top of the stratum basale so is still close to the blood supply. The cells in this layer are also metabolically and mitotically active
Keratin
tough fibrous protein that makes the epidermis more resistant to mechanical trauma.