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