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
describe apocrine secretion
some tissue stays intact - mix of holo and mero
describe merocrine secretion
opposite of holocrine
just cellular contents (secretory product) - gland stays intact
describe sweat gland
merocrine secretion
simple tubular gland
myoepithelial cells sit on BM
what are myoepithelial cells
specialized cells for contractility
describe how sweat gland secretes
myoepithelial cells contract and pushes sweat and makes it to excretory gland
and sweat pore
sweat pools in lumen of gland
what does sweat gland secrete
water
urea
ammonia
NaCl
what is purpose of sweat gland
thermoregulation by evaporative cooling
describe excretory portion of sweat gland
in hypodermis and dermis
smaller and darker stain
compound stratified cuboidal cells (2 layers)
describe secretory portion of sweat gland
in hypodermis
simple columnar/pyramidal when H&E stain
actually has 2 layers but can only be seen with special stain that stains myosin
why is lumen of excretory portion smaller
reduce volume of lumen so sweat comes out faster - still same pressure
