Structure of the Skin Flashcards
describe thin skin
4 thinner epidermal layers that covers all remaining parts of the body. Not palm, soles, fingers, toes,
describe thick skin
5 epidermal layers and covers palm, soles, fingers, toes, surface layer has dead cells and lacks hair follicles.
Epidermis organization
keratinized stratified squamous epithelium organized into several distinct strata.
Structure of stratum basale
single layer of cuboidal or columnar cells. (Keratinocytes, melanocytes, merkel cells)
Function of stratum basale
continuously undergo mitotic cell division to produce new skin cells.
keratinocytes
most abundant cells, are held together by desmosomes. tough, fibrous keratin protects skin from heat, microbes, chemicals, helps to waterproof skin.
melanocytes
synthesize melanin; responsible for skin color; absorbs ultraviolet radiation to protect skin from damaging effects of sunlight.
merkel cells
tough receptors that join with sensory neurons to form merkel discs.
structure of Stratum spinosum
several layers of keratinocytes; that can change shape. (dendritic cells)
Function of Stratum spinosum
skin preparations for microscope slides where keratinocytes shrink and pull apart, except where attached by desmosomes gives the layer “spiny” appearance.
dendritic (Langerhans) cells
macrophages that arise in bone marrow and migrate to epidermis to protect body against microbes that invade skin; source of nutrients.
Structure of Stratum ganulosum.
keratinocytes that contain dark-staining granules of protein that eventually become keratin.
Function of Stratum Ganulosum.
The keratinocytes flatten, then nucleus and organelles disintegrate and granules of keratin accumulate in cytoplasm. keratinocytes die and release waterproofing glycolipids that form barrier between stratum spinosum and stratum granulosum. outer limit for diffusion of substances.
Structure of stratum lucidum
thin, translucent layer of dead cells found only in thick skin.
Structure of stratum corneum
up to 30 layers of dead, scaly keratinized cells and makes up about 75% of thickness of epidermis.