Epidermis Cell Types
Layers of the Epidermis
Stratum Basale Stratum Spinosum Stratum Granulosum Stratum Lucidum Stratum Corneum
Hypodermis
-bottom layer -made up of adipose tissue
1) Stratum Basale
-bottom layer -single cell layer in thickness -contains all 5 cell types -where basal cells reside--->where new keratinocytes are made
Psoriasis
-caused by the immune system attacking and killing keratinocytes --->premature death & flaking/shedding of keratinocytes -genetic condition--keratinocytes produce an abnormal form of keratin
Basal Cells
-divide and produce new keratinocytes -located in the bottom layer of the epidermis
Drandruff
-fungal infection of hairy skin -he fungus causes keratinocytes to die prematurely and flake off in large sheets/flakes
Langerhan Cells
-immune cells -undergo phagocytes (endocytosis) of bacteria & fungi
Merkel Cells
-located in bottom layer of epidermis -touch receptors -wired to nerves
Reticular Region
-lower region -dense irregular connective tissue -provides the skin w/ strength & toughness stretch marks: scars in the reticular region
4) Stratum Lucidum
-made up of dead,clear keratinocytes -the layer is only present in "thick skin" (palm & sole skin)
3) Stratum Granulosum
-made up of keratinocytes -the keratinocytes are filled w/ lipid vesicles --->they release the lipids via exocytosis ---->the lipids help waterproof the epidermis
2) Stratum Spinosum
-mainly contains newly formed kerotinocytes, melanocytes, and langerhans cells are also present -where the kerptinecytes absorbs melanin -keratinocytes appear "spiny"---> their desmosomes look like spines
Dermis (2 layer/region)
-middle layer of the skin -contains nerves, blood vessels, bodies of glands ---papillary region, reticular region
Keratinocytes
-most abundant cell type -filled with the intermediate filament "keratin" -neighboring keratinoctyes are connected by desmosomes and tight junctions -fill w/ lipid vesicles/granules that they release to help waterproof the epidermis
Melanocytes
-produce the pigment "melanin" -they release their melanin, and the melanin is absorbed by keratinocytes
5) Stratum Corneum
-upper layer -made up of dead keratinocytes -dead keratinocytes on its surface are shed
Papillary Region
-upper region -areolar connective tissue -contains ridges called dermal papillae that help bind the epidermis---dermis -in thick skin the dermal papillae are large & form ridges along the papillae --->gives rise to sole,palm,fingerprints
Anti-Dandruff Shampoos
contain anti-fungal drugs