Flashcards in Histology 1: Integument Deck (19):
dermal ridges OR dermal papillae
projections coming up from the dermis which interlock with complimentary ridges in the epidermis.
Principal cells of the epidermis
Bottom most layer of the epidermis, single layer of cuboidal cells - only layer in which mitosis takes place. Adjacent cells of stratum basale are bound together by desmosomes, and cells are bound to the dermis by hemidesmosomes. Contains scattered course filaments: tonofilaments
Layer made up by the stratum basale and stratum spinosum.
Characterized by cells which have shrunken away from each other but are still connected by desmosomes and therefore look spikey-- "prickle cells". Also contains tonofilaments-- increase in amount and combine to become tonofibrils. Stratum spinosum also contains membrane-coated granules (lamellar bodies) that contain glycolipids (maintains waterproof barrier function of the skin)
3-5 layers of cells. Cells in this layer have begun to flatten out. Contain densely packed granules of keratohyalin associated with tonofibrils. Produces keratin (with tonofibrils). Apoptosis of keratinocytes occurs in this layer as cells fill with keratin. lamellar bodies empty their glycolipid contents into intercellular space.
Only seen in thick skin. Characterized by the loss of nuclei, and tonofilaments are oriented parallel to the skin
Surface layer of the epidermis, cells are now dead, flattened, and completely keratinized. Cells have no nuclei, organelles, or cell junctions.
Determines skin pigmentation. skin color = 2 pigments: carotene - yellowish pigment found in stratum corneum and fat. Melanin pigment - produced by melanocytes, is either brownish-black OR reddish-yellow in color. Fxn: to protect stratum basale from harmful ultraviolet radiation.
*Found in stratum basale and project into stratum spinosum. Functionally related to 4-10 keratinocytes = epidermal-melanin unit. Deposit granules into keratinocytes within their unit.
*found in all layers of epidermis, but especially upper layer of stratum spinosum.
Fxn: trap antigens that penetrate the skin surface and transport them to regional lymph nodes.
*Involved in the occurrence of contact dermatitis
widespread, especially in stratum basale.
*Found close to intraepithelial free nerve endings
Fxn: mechanoreceptors involved with touch reception.
Papillary layer of the dermis
forms dermal ridges ("dermal papillae"). Lies immediately deep to the epidermis. Less fibers, more cells.
Reticular layer of the dermis
Lies below the papillary layer, blends in with the hypodermis. Contains abundant amounts of collagen fibers. In some areas contains Langer's lines
parallel lines of collagen fibers within the reticular layer of the dermis. Of surgical importance: incisions made along Langer's lines gape less and heal with less scar tissue than incision made perpendicular to Langer's lines.
Encapsulated nerve endings found in the dermis
1) Meissner's corpuscle
2) Pacinian corpuscle
3) Ruffini corpuscle
4) Krause end bulb
Touch receptor found in the papillary layer of the dermis
Deep pressure receptor found in the deep dermis and hypodermis