integument Flashcards
(23 cards)
is hypodermis part of skin?
no
Skin layers
Epidermis, Dermis, Hypoderis (not part of skin)
Hypodermis
- subcutaenous connective tissue
2. panniculus adiposus (superficial fascia)
Thick skin
palmar, plantar
“thick” referes to the thickness of epidermis
Sweat glands are the most numerous here
No hair
Distinct grooves/ridges reflect underlying dermis
Both keratinized and underlying layer of epithelial cells are thick
Thin skin
Rest of the body (Beside plamar, plantar)
Epidermis is much thinner (especially stratum corneum)
5 Layers of Epidermis
Stratum basale stratum spinosum stratum granulosum stratum lucidum stratum corneum
- Stratum basale
- Single layer of basophilic columnar/cuboidal
- Rest on basal lamina at dermal-epidermal junction
- Many desmosomes between lateral and superior adjacent cells
- hemidesmosomes bind cells to basal lamina
- Essential composed of stem cells
- Many mitotic figures (renewing every 15 days)
- cells contain intermediate filaments called cytokeratins/keratins which increase as cells mature and migrate toward surface
- By the time the cells are in stratum corneum, cytokeratins make up 50% of protein in cell
- stratum spinosum
- polygonal cuboidal, slightly flattened cells
- cytoplasm is full of bundles of intermediate filaments which make attachments at the site of the desmosomes (create spiny due to cells pulled apart except at desmosome places)
- cell
- stratum granulosum
- relatively thin (3-5 cells thick)
- contain 2 types of granules
- Keratohyalin granules - basophilic, rich in protein, no membrane, keratin filaments, precursor of interfibrillar material.
- lamellar/membrane coating granules - secretory granules, staacks of flattened vesicles, does exocytosis to form multilayer coating (membrane), upon exocytosis the material fill the intercellular space which is rich in lipid which acts as waterproof barrier
- involucrin protein to coat the cytoplasmic side of plasmalemma.
- Stratum lucidum
- thin, eosinophilc
- organelles and nuclei are disrupted or absent
- cytoplasm consists of densely packed filaments in electron dense matrix made from keratohyalin granules.
- Stratum corneum
15-20 layers of keratinized, flattened, denucleated cells whose cytoplasmic sacs are filled with keratin filaments embedded in an amorphous matrix.
Effect of solar radiation on epidermis
long term exposure to the sun induce epidermal changes.
carcinoma preceded by increased keratinization called actininc or solar keratoses.
common in fair-skinned people
melanocyte embryology
neural crest
melanocyte location
beneath and in between stratum basale.
Sometimes in dermis, hair follice
melanocyte shape
round cell bodies with long dendritic projection that terminate near teh wall of keratinocytes in stratum basale/spinosum
melanocyte function
production of melanin, seen in cytoplasm as granules termed melanosomes
melanocyte recognition in tissue
melanocytes produce but do not store in melanin, hence their cytoplasm is pale
melanocyte action
cytocrine secretion.
vesicles containing multiple melanosomes are pinched off from melanocyte dendrites.
Vesicles fuse with plasmalemma of adjacent keratinocytes and are incorporated by endocytosis into keratinocytes.
Stratified squamous cornified
epidermis
Clear cells
melanocytes
Langerhan’s cell - macrophages that migrate into the dermis and activating lymphocyte
Markle tactile corpuscle - sensory receptors, responsive to temperature
hypodermis
consists of adipose tissue
Dr. Gerrard Eats Ice Cream Cake in Morning
Dermal sheath - layer of CT
Glassy membrane - basement membrane of ERS
External root sheath - stratified epithelium
Internal root sheath - 2 layers of refractive cells
Cuticle - several layers, flattened cells
Cortex
Medulla - in hair above epithelium
arrector pili muscle
dimples skin, FOCES SEBUM FROM SEBACEOUS GLAND
