Skin Flashcards
epidermis
1st layer of epithilia, protective, keratinocytes- most abundant cells.
Dermis
source of nutrients for unvascularized epithelium, flexible base, contain hair follicles and sweat glands
Hypodermis
superficial facia, insulator- lots of fat, shock absorber
functions of skin
- protection- keratin layer is barrier, protection from water
- sensation- temp/ touch/ pain
- thermoregulation- constant core body temp, sweat vasoconstrict to conserve heat
- metabolism- vitamin D synthesis then goes to kidney and liver
Layers of the epidermis
- basal layer
- spinous layer
- granular layer
- lucid layer- only in realy thick skin
- cornified layer
basal layer
separated from the dermis by the basement membrane with hemidesmosomes. Mitotic activity all cell division happen here
spinous layer
have cells than synthesize cytokeratins that aggregate to form tonofilaments- which associated with desmosomes and hemidesmosomes.
granular layer
keratohyalin granules are present, high in protein, filaggrin- dense packing of filaments, lamellar bodies- secrete glycolipids for hydrophobicity
cornified layer
layers of fried waxy keratinized cells, cells apoptosis,
basal lamina
lamina lucida- clear zone
lamina densa- filamentous type 4 collagen
Hemidesmosomes
target for autoimmune diseases causing blisters to form- ex. pemphigus
Nonkeratinocytes: langerhans
antigen presenting cells, trap external antigens to send to lymph nodes, found in suprabasal layer
nonkeratinocyte: melanocyte
have cytoplasmic extensions, cover nucleus from UV radiation
nonkeratinocyte: merkel cells
basal layer, touch receptors
Dermis:
- papilary layer: loose connective tissue
- reticular layer: dense irregular connective tissue
contains secretory gands, hair follicles, fibroblasts, collagen, proteoglycans