Histo Midterm 2 - Skin Flashcards
What are the 2 main layers of skin?
Epidermis - derived from ectoderm
Dermis - derived from mesoderm
What type of tissue makes up the epidermis?
Stratified squamous epithelium
What are the features of Thick skin? Locations?
Locations: palms of hands, soles of feet, callouses
5 Layers
- 1)Stratum basale/germinativum
- 2)Stratum spinosum
- 3)Stratum granulosum
- 4)Stratum Lucidum
- 5)Stratum Corneum
What are the features of the stratum basale layer?
Basophilic cuboidal-like cells (pre-keratinocytes)
Hi mitotic activity
Renewal @ 15-30 days
Irregular basement membrane
Contain: numerous hemidesmosomes, melanocytes (synth melanin pigment, derived from neural crest), Merkel’s cells
Where are Merker’s cells located?
Palms, soles, and oral mucosa
What are the features of Stratum spinosum layer?
Many layers
Prominent intercellular bridges (Desmosomes)
Keratinocytes - produce membrane-coating granules
Tonofilaments - intermediate filaments in desmosomes
Langerhans cells
What are Langerhans cells?
defense cells
What are the features of the stratum granulosum layer?
3-5 layers of flat polygonal cells
Coarse basophilic granules of keratohyalin
What are the features of the Stratum lucidum layer?
Only in thick skin
Flat cells w/ no nuclei or organelles
Cells filled w/ eleidin (intermediate keratin)
What are the features of the stratum corneum layer?
15-20 layers of flat non-nucleated cells
Filled scleroprotein keratin
Layer determines thick or thin skin
What are the features of thin skin?
Reduced thickness of all layers
Typically have: corneum, intermediate, and basale layers
No stratum lucidum
What is the difference between Rete pegs and Dermal papilla?
Rete pegs - downward projections of epidermal cells
Dermal papilla - upward projections of epidermal cells
What are the 2 layers of the dermis?
Papillary layer and Reticular layer
What are the features of Papillary layer?
Layer immediately under epidermis
Thin loose CT w/ anchoring fibrils (Type IV) in basal lamina
Dermal papilla
Meisner’s corpuscles - sensory receptor for touch
What are the features of the reticular layer?
Consists of DICT (type 1) and elastic fibers
What are the glandular units in the dermis?
Secretory units that use merocrine/eccrine type of secretion
What are the features of the sweat gland ducts?
Begin in the reticular layer -> extend upward and penetrate into Rete pegs -> spiral towards the surface
Stratified cuboidal epithelium
Contain myoepithelial cells at the basement mebrane (function: squeeze)
What tissue makes up the subcutaneous layer?
Hypodermis - mainly adipose tissue, numerous blood vessels, nerves, and receptors
Location: Giggle when you wiggle
What are the structures of the hair?
Hair follicle - formed from epithelial downgrowth
Root sheaths - composed of stratum basale, stratum spinosum, and CT
Hair shaft - medulla, cortex, and cuticle
Arrector pilli - smooth muscle attach to each follicle; cause hair to “stand on end”
Sebaceous glands - protect hair w/ oils; example of holocrine secretion
Features of each layer of hair shaft?
Medulla - continuous serious of air pockets at the center of the hair
Cortex - dense compacted keratin
Cuticle - layer of keratinized scale-like cells covering shaft
What determines hair color?
Activity of melanocytes covering hair papilla
Features of nails?
Nail bed - epithelial tissue under nail plate
Nail matrix - where new nail is formed
Lunula - anterior edge of new nail
Cuticle/eponychium - holds nail plate at proximal end and protects against microorganisms
What are the functions of the skin?
Temperature control, mechanical barrier, regulation barrier, regulation of water loss, excretion of waste, storage of fat, synthesis of vitamin D, receptors for sensations
