layers of epidermis function and structure

stratum corneum structure

Most superficial stratum of the epidermis; 25 or more layers of dead squamous cells

stratum corneum function

Provides structural strength due to keratin within cells; prevents water loss due to lipids surrounding cells; sloughing off of most superficial cells resists abrasion

stratum lucidum structure

a thin, clear layer of dead skin cells: found only in palms and soles :present in thick skin

stratum lucidum function

disperses keratohyalin around keratin fibers

stratum granulosum structure

flattened diamond shaped cells, contains keratohyalin

stratum granulosum function

Produces keratohyalin granules; lamellar bodies release lipids from cells; cells die

stratum spinosum structure

limited cell division, appear star shaped bc the plasma membrane pulls away from the other cells except where the cells are joined at microscopic junctions called desmosomes

stratum spinosum function

produces keratin fibers : lamellar bodies form inside keratinocytes

stratum basale structure

Single layer of cuboidal or low columnar cells sitting on basement membrane

stratum basale function

produce cells of the most superficial strata: melanocytes produced and contribute melanin which protects against UV light

epidermis is made of this type of tissue

stratified squamous epithelium

keratin

a tough protein found in the skin, hair, and nails

Melanocytes

cells that produce melanin

Melanin

a dark brown to black pigment occurring in the hair, skin, and iris of the eye in people and animals. It is responsible for tanning of skin exposed to sunlight.