Epithelial Tissue: skin annexes Flashcards
describe melanocytes
round body shaped cells
makes melanin granules
where do melanocytes rest
underneath or in between stratum germinativum stem cells
describe process of melanocytes
sends finger like projections with developing melanin granules
projections are phagocytize
budding tentacles come out and pinches off (form of vesicle)
goes into cell and releases melanin
melanocytes make umbrellas to cover cells of stratum spinosum (to protect from uv rays)
active process
name the 2 types of melanocytes
eumelanin - brown
pheomelanin - red (more cysteine bonds)
why do we have hair
thermoregulation (sweat, hair stands up and air between hair creates heat)
protection
sensation (whiskers)
goosebumps (communication)
describe sebaceous gland (location)
at neck of polysebaceous unit
describe hair shaft
visible
follow it down to follicle
name and describe parts of hair shaft
medulla - animals dont have one
cortex
cuticle
flat keratinized cells
describe hair follicle
around where hair shaft becomes continuous with follicle and then follicle becomes continuous with bulb
describe hair bulb
invagination of connective tissue (dermal papilla)
super vascularized - with nerves
why does pulling hair hurt
firing nerves in dermal papilla
what does arrector pili cause
goosebumps
what is glassy membrane
basement membrane
separates connective tissue from epithelial tissue
what gives hair colour
melanocytes on BM
describe CT sheath
wraps around hair bulb and comes inside (dermal papilla)
name layers of hair follicle
connective tissue sheath
glassy membrane
external root sheath
internal root sheath
cuticle of hair shaft
cortex
describe internal root sheath
henle’s layer - flat cells
huxley’s layer - trichohyalin granules
cuticle of IRS = flat
describe sebaceous gland
non squamous stratified epithelium
polygonal (round cells)
what does sebaceous gland have (what is inside cells)
lipid droplets containing cholesterol, phospholipids, triglycerides and glycogen
look empty bc ethanol dissolves fats
what is sebaceous gland stimulated and inhibited by
stimulated by androgens
inhibited by estrogens
what does sebaceous gland make
sebum (pheromones, bacteriostatic permeability)
released when cell dies
what is acne
sebaceous glands starting to work
describe what happens during sebaceous gland secretion
base layer of stem cells (dark pink) can differentiate into cells that make fats
stem cells and major glands make lipids - make so many that cell explodes and releases its contents and dead cells
dead cells enucleated - contents being emptied into shaft
describe holocrine secretion
sebaceous gland
contents of cell and dead cell - everything is secreted
