Lecture 3: Epithelial Tissues Flashcards
side of cell that faces the external environment
apical domain
side of cell that is in contact with neighbor cells
basolateral domain
side of cell in contact with the basal lamina
basal domain
what are the 3 germ layers epithelial tissues are derived from?
ectoderm
endoderm
mesoderm
ectoderm
epidermis and glands
endoderm
lining of GI tract and glands
mesoderm
lining of blood vessels
epithelial tissues rest upon a _____ .
basement membrane
components of the BM
basal lamina
reticular lamina
BM layer next to epithelial layer
basal lamina
composed of type IV collagen and glycoproteins
PAS+
BM layer not next to the epithelial layer
reticular lamina
in contact with underlying CT
composed of: argyrophilic fibers, reticular fibers, glycoproteins
functions of the BM
selective filtration barrier
scaffolding for genesis and regeneration
stabilize tissue shape
simple vs. stratified
one vs. more than one layers
shapes of epithelial cells
squamous — flattened
cuboidal —- height = width
columnar —- height > width
special categories of epithelia
pseudostratified
transitional
other name for transitional epithelium
urothelium
what makes urothelium special?
changes shape depending upon volume within cavity
all cells are in contact with basal lamina
what makes pseudostratified special?
appears stratified but all calls are in contract with basal lamina
nuclei are at different height
lower = stem cells
surface modifications
cilia
stereocilia
microvilli
lightly keratinized
vagina
esophagus
heavily keratinized
skin
what does it mean to be keratinized?
cells are dead
have no organelles or nucleus
are filled with the protein keratin
keratin is responsible for making our skin ______ .
waterproof
which domains of epithelial cells have surface modifications?
apical domain
junctions between basolateral domains
tight junctions — seals
no extracellular matrix
keeps cells together and create barriers
can be leaky or tight barriers
brush border
microvilli
finger like projections
cilia
finger like projections that are non-motile
stereocilia
longer than cilia and can be branched
simple squamous locations
lining of ducts, vessels, tubular structures
walls of alveoli
inner surface of membranes
tympanic membrane
simple cuboidal locations
kidney tubules
ovary surface
glands and ducts
simple columnar locations
intestinal cells upper respiratory tract uterine tubes uterus digestive tract
stratified squamous locations
keratinized - skin, cornea
light/non - esophagus, vagina, mouth lining, tongue, epiglottis
stratified cuboidal locations
very rare
anal mucosa
male urethra
large excretory ducts
stratified columnar locations
very rare ducts of sweat glands whites of the eye male reproductive/urinary tract pharynx epiglottis
pseudostratified locations
trachea
epididymis
transitional locations
urinary system
types of epithelium involved in secretion and absorption
simple or pseudostratified epithelium
simple columnar
microvilli properties
non-motile brush border
supported by cross-linked actin bundles
microvilli function
to increase surface area of absorption
microvilli locations
intestinal epithelium
renal tubules
microvilli structure
actin filament core
formin cap on distal end of actin filaments
microvilli core properties
extends into terminal web of cytoskeleton
core filaments are cross-linked by villin and fimbrin
cilia structure
9 peripheral doublets
central pair of microtubules
cilia doublets
consists of an alpha and beta tubules
alpha tubule
of the cilia doublet
contains: 13 protofilaments
radial spokes that extend to sheath around central pair
spokes help anchor the tubule
pairs of dynein arms that extend to neighbor tubule’s beta unit
beta tubule
of the cilia doublet
smaller than the alpha and only half a circle
10-11 protofilaments
cilia functions
either move mucous back and forth
or
move the cell not surround material
