W4 skin histopathology Flashcards
layers of skin
epidermis
papillary dermis
reticular dermis
subcutis
epithelial layers (out to in)
corneum (lucidum) granulosum spinosum basale
epidermal cell matural time
4 weeks
-starts in basal layer and goes through until it is shed in the corneum layer
stratum granulosum
- highest layer with living cells
- lipid containing membrane coated granules that are exocytozed to produce waterproof barrier
- kerato-hylain granules
- filaggrin with keratin bundles
stratum corneum
- non nucleated keratinocytes important to barrier function
- 15-20 layers of dehydrated keratinocytes
- tonofillaments containing filaggrin
- barrier against trauma, infection
orthokeratosis
-normal basket weave looking stratum corneum
strutum lucidum
- only found in palms and soles of feet
- contains eledin which becomes karatin
stratum spinosum
- joined by spiny desmosomes (join intermediate filaments in neighboring cells)
- synthesize cytokeratins to provide structural support and helps resist abrasion
- cuboidal cells with dark nuclei
stratum basale
-single layer of columbar keratinocytes undergoing rapid proliferation and mitosis to replenish skin loss at surface
epidermis cells
keratinocytes (80%)
melanocytes (10-15%)
merkel cells (1%)
langerhans cells (3-5%)
melanocytes
- second most prevalent cell in epidermis
- derived from neural crest cells during embryogenesis
- responsible for skin pigmentation
- about 1 per every 10 kerationocytes
- show up in histology with a halo around cytoplasm
Langerhans cells
- bone marrow derived
- common in stratum spinosum
- antigen presenting
- contain birbeck granules (look like tennis rackets)
Dermis components
collagen elastic tissue blood vessels nerves fibroblasts epidermal appendages
solar elastosis
- solar damage to elastin in dermis
- causes elastin to look blue
fibroblasts
- important in wound healing
- produce collagen
- primary cells of the dermis
- produce elastin and ground substance
- bland spindle cell appearance
smooth muscle bundles
- found in dermis
- look like a purple rod with many nuclei
sebaceous glands
- undergo holocrine type secretion
- found near hair follicles
- blue, cuboidal looking clusters of cells with a dark purple outline
- everywhere except palms and soles
- most numerous on face, chest, back scalp
- functionally active at puberty
- sebum provides emollients to hair/skin
- dying cell releases secretory products
- secretion regulated by hormones
pilosebaceous unit
hair follicle
sebaceous gland
arrector pili muscle
apocrine glands
- found in axilla and groin
- simple columnar
- malodorous due to bacterial action
- secretion itself is odorless
- stimulated in excitement and fear
- mikly viscous fluid
- not active until puberty
- secretory products stored in cell
eccrine glands
- every except mucous membranes
- cuboidal
- thermoregulation
- duct transverses dermis and epidermis and opens onto superficial surface
- merocrine secretion (vesicles) regulated by SNS
hypodermis/subcutis
- fat layer between dermis and underlying structures such as fascia and muscles
- insulates body
- energy supply
- cushions and protects skin
- allows for mobility over underlying structures
functions of skin
- regulate water loss
- maintain temperature
- protect from UV
- provide physical barrier from external environment
- nerve sensation
- injury repair
- appearance and quality of life
sensory receptors
- thermoreceptors
- meissner’s corpuscle for touch
- nociceptor for pain
- pacinian corpuscle senses pressure
- mechanoreceptors for interacting with objects
parakeratosis
-presence of keratinocytic nuclei in stratum corneum
hyperkeratosis
-thickened stratum corneum
acanthosis
-thickened spinous layer
acantholysis
loss of attachment between keratinocytes – free floating keratinocytes
