INTEGUMENTARY 1 Flashcards
what are the functions of skin
Protection, fight bacteria, prevents water/heat loss
what are the two distinct regions of skin
Epidermis: epithelial cells
Dermis: bulk of skin
what does the hypodermis do
anchors skin to muscle
whats the epidermis
the avascular outermost protective layer thats Made up of epithelial cells
what are the four cell types on epidermis
keratinocytes, melanocytes, dendritic cells, tactile epithelial cells
what are the five layers on epidermis
stratum basale, spinosum, granulosum, lucidum, corneum
give function of keratinocytes, melanocytes, dendritic cells and tactile/merkel cells
Keratinocytes: produce keratin
Melanocytes: produce melanin
Dendritic cells: phagocytes; key immune system activator
Tactile (merkel) cells: sensory receptor for touch
what are the most abundant cell types + where do they come from + what are they zipped up by
keratinocytes that come from stratum basal and are zipped up by desmosomes and tight junctions
what do keratinocytes produce
keratin - a fibrous protein that gives epidermis its protective abilities
how are keratinocytes pushed up/created
Continuously undergo mitosis and are pushed up the layers
Dead, flat sacs once they reach the surface
Friction increases proliferation
Hands and feet have increased keratin production
why do we have new epidermis every 25-45 days
because of constant regeneration
where are melanocytes found
stratum basale
what do melanocytes produce
melanin, which is stored in keratinocytes
where in the melanocytes is melanin produced
in melanin granule (melanosomes)
why do melanocytes cluster on top of skin
because they protect skin from UV radiation
order layers from deepest to most superficial
Stratum basale
Stratum spinosum
Stratum granulosum
Stratum lucidum
Stratum corneum
whats the stratum basal? what is it attached to and what does it contain? how much of it is melanocytes
Deepest layer
Attached to dermis
10 – 25% of cells are melanocytes
Consists of single layer of stem cells
» Continuously dividing
» One cell pushed upwards
» Other cell stays in place
whats the stratum spinosum
prickly layer thats Several layers thick
what do keratinocytes in stratum spinous contain
pre-keratin » Resistant to tension
where are dendritic cells most abundant
stratum spinosum
whats the stratum granulosum
Thin layer where keratinization begins
what happens to cells, nuclei and organelles in stratum granulosum
Cells flatten, nuclei and organelles degrade,
accumulate granules
» Become tough and water resistant
is the stratum granulosum cut off from blood supply
yes
describe startum lucidum
Only present in thick skin
Few layers of dead keratinocytes
describe startum corneum
Thickest and outermost layer
20 – 30 cell layers thick
Waterproof
Shed regularly (dandruff)
what do keratinized cells in stratum cornum do
Keratinized cells protect from abrasion and penetration
whats the dermis of the skin
“animal hide”
Bulk of skin
Made of strong flexible
connective tissue
what does the dermis of the skin contain
blood vessels, nerve fibers, lymphatic vessels, and hair follicle
what cells are present in the dermis
fibroblasts, macrophages, WBCs
what are the two layers in the dermis
papillary and reticular dermis