Epithelium Flashcards
what is present between epithelium and connective tissue?
basement membrane or basement lamina
what does the basal lamina composed of
adhesive glycoproteins laminin, anchored by adhesive glycoprotein entactin and heparan sulfate perlecan and collagen type IV fibril
luminal surface of heart, blood vessels, lymph vessels are lined by what type of epithelium?
endothelium
body cavities (pleural, pericardial, peritoneal ) are lined by what epithelium?
mesothelium
different types of covering epithelium?
simple
stratified
pseudostartified
the two type of cells in psedustratified ?
tall columnar and short
what type of cells in pseudostratified faces the lumen of the organ ?
the tall columnar
what are the shape of simple squamous in outline?
polygonal
where is the nucleus present in the simple squamous?
in the center
when cut perpendicular (simple squamous) what do they give appearance of? and why?
fusiform (spindle shaped) because the central region is thicker then the peripherally cytoplasmic region
list down the places where simple squamous is present?
the endothelium (inner surface of hear, bood vessels, lymph vessels) and mesothellium ( plerual, pericardial and peritoneal cavity) also type I alveolar cells
surface view of simple cuboidal cells show what shape?
hexagonal
what is the shape and location of nucleus in simple cuboidal?
center and spherical
location of simple cuboidal epithelium?
the follicles of the thyroid gland
and distal convoluted tubule
the shape and location of nucleus of simple columnar cells?
oval and near the base of cell
where are simple columnar cells present?
in stomach, intestine, uterus and gallbladder
what are the modifications on simple cuboidal cells and on what surface?
on the apical surface and it has microvilli, stereocilia, kinocilia
the basal layer of stratified squamous is what shaped?
low columnar or cuboidal
the layer next to basal layer is what shaped cells?
its polygonal cells
2 types of stratified squamous?
keratinized and non keratinized
the intracellular space b/w the squamous cells in stratified squamous contains what?
water proofing glycolipid
the stratified squamous non keratinized epithelium has what difference with keratinized?
it doesnt contain keratin. it has nucleus
where is keratinized stratified squamous epithelium present?
epidermis of our skin
where is non keratinized stratified squamous epithelium present?
oropharynx, esophagus and oral cavity
where is stratified cuboidal epithelium present?
epithelial lining of larger ducts (pancrease and salivary glands)
where are stratified columnar epithelium present
conjunctiva of the eye and male urethra
where is transitional epithelium present?
lower urinary tract
what is another word of transitional epithelium?
urothelium
what it is urothelium specially designed for?
to withstand the stretch produced by distention of the urinary passage because of storing and colaection of urine.
urothelium prevents?
the diffusion of urine back into the tissues of the urinary tract
in undistended urothelium how many layers present?
6 layers
what is the shape of 3 layers?
basal layer is cuboidal
upper layer of basal is polygonal
and the superficial layer is convex (umbrella shaped)
in distended how many layers present?
3 layers
the area that is rigid and thick on the superficial layer on transitional epithelium are?
plaque
what are fusiform vesicle ?
when the luminal plasma membrance of the superficial layer folds the plague invaginate into the cytoplasm and these temporary stored invaginations are called fusiform vesicle
what are the two features which make the transitional epithelium impermeable barrier ?
- laminal plasmalemma of the cells are impermeable to salts
2. cells are strongly bound with zonula occludentes and multiple desmosomes
where are pseudostartified columnar epithelium present?
conducting respiratory tract
and male genitial ducts
modifications of pseudostratified epi?
kinocilia and stereocilia
shape of neuroepithelia
tall columnar
location of neuroepithelia?
taste buds and vestibulocochlear receptor system of internal ear
shape of myoepithelial glands?
star shaped
location of myoepithelial glands?
secretory acini of mammary, lacrimal, sweat glands
what are microvilli?
slender small finger like projections on the surface of epithelial cell facing the lumen of an organ
central bundle of microvillus contains?
20-30 microfilaments
these microfilaments are joined by?
actin binding protein fimbrin and fascin
microvilli when extending into the apical cytoplasm get embedded in?
terminal web
microvilli at terminal web are associated with?
spectrin and myosin-II
what place of internal epithelial surface is known as striated border?
small intestinal columnar epithelial cells
microvilli are also present where except intestine?
proximal convoluted tubule
association of microvilli with myosin-II allowes?
contractile oscillatory movement
where are cillia found?
where there is transport of fluid or film of mucus
location of cillia?
respiratory tract, uterine tube, neuroepithelium
cillia is kinocilia why?
because it has to and fro motion
there is a core complex of microtubules in cillia called?
axoneme
there are microtubules arranged in axoneme how?
9+2 arrangement
how many of these microtubules are doublet?
2
how many is a single pair and where they are?
one single and on central part
all these microtubules are enclosed in a thin sheath called?
central sheath
microtubule A has how many protofilaments?
13
B has?
10
the adjacent doublets are linked with each other thorugh?
protein bridge called nexins
the doublets are radially joined to the central sheath by?
spoke
prootfilament A has hook type arms on the outer covering made of protein?
dynein
dynein makes temporary?
cross bridges when activated by atp with microtubule B
why stereocilia called stereocillia?
they are still and can not move
why stereocilia give tuft like appearance?
they are long flexible and their ends wind with each other giving a tuft look
where are stereocilia present?
epididymis and vas deferens
what is the function of stereocilia in epididymis and vas deferens
increase mucosal surface area for reabsorption of the fluids and spermatozoa
two main functions of lateral domain?
adhesion and cell to cell communication
on what adhesion of lateral domain is dependent on?
cadherin ( adhesive glycoprotein)
presence of invagination and evaginations
and adhering and occluding junctions
cell to cell communication is dependent on?
nexuses
3 features of basal domain
- basement membrane
- hemidesmosomes
- infoldings of plasmalemma
what is basement membrane?
is the extracellular material between the epithelial cells and the underlying connective tissue
what is hemidesmosomes/
hemidesmosomes connect the epithelial cells to the basal lamina
infoldings of plasmalemma is a special feature of those cells which are involved in?
active transport of ions and molecules
how infoldings accommodate active transport?
increase surface area, more transport proteins and has mitochondria?
where is mitochondria present in infoldings?
between the infoldings
the basal regions of those epithelial cells which have infoldings show what type of striations and in what stain?
eosinophilic striations in H&E stain
these striations are made by?
mitochondria
where are these infoldings and striations present?
prox and dist convoluted tubules and salivary glands
the membrane of basal lamina is composed of two layers:
basal lamina and reticular lamina
what is the thickness of basal lamina?
80-100mm
components of basal lamina?
fibrils of collagen type IV
glycoprotein laminin
entactin which holds the laminins together
heparan sulfate- perlecan
basal lamina has two layers called as?
basal lucida and basal densa
what does reticular lamina composed of?
reticular fibrils glycosaminoglycans heparin sulfate hyaluronic acid collages type VII
where in body a single basal membrane present b/w two epithelial cell layers
alveoli and glomerulus
