Epithelium Flashcards
Epithelial tissues ___ and __ all body surfaces
cover and line all body surfaces, cavities, tubes, and form glands for secretion
epithelial tissues have the capacity to for ___ for secretion
glands
6 general functions of epithelial tissues
1) protection 2) diffusion 3) absorption 4) secretion 5) filtration 6) lubrication
cells of epithelial tissues are bound together by ___ ___
CELL JUNCTIONS
T/F: epithelial tissues are vascular
false. they are avascular
the ___ ___ portion of the epithelial cellrests on the basal lamins
BASAL POLE
what lies under the basement membrane?
connective tissue
the ___ __ of the epithelial cell faces a space, typically lumen.
apical pole
3 ways epithelia are classified
1) number of cells (simple/statified) 2) shape (cuboidal, squamous, columnar) 3)specializations (cilia, microvilli, stereocilia)
4 Functions of SIMPLE epithelia
1) diffusion 2) filtration 3) absorption 4) secretion
2 special simple squamous epithelium
1) endothelium: lining heart and vessels. 2) mesothelium: lining serous membranes and secretes lubricating fluid
why may the endothlial lining of an artery be harder to see than a vein?
the endothelial artery may be overshadowed by the thick elastic fibers facing the lumen. you may be able to see the nuclei ON the fibers, but you can’t fully see the entire squamous cell.
serous membranes of the pleura, pericardium and peritoneum are known as ____ and are made of ___ ___ epithelium
serous membranes of the pleura, pericardium and peritoneum are known as MESOTHELIUM and are made of SIMPLE SQUAMOUS epithelium
3 functions of simple cuboidal epithelium
1) excretory 2) secretory 3) absorptive functions
Locations of simple cuboidal epithelium
1) kidney tubules 2) ovary 3) thyroid 4) certain ducts (bile duct, sweat gland duct)
where is the nucleus located in simple columnar epithelium?
generally located at the bottom half
2 “accessories” that simple columnar epithelium have
1) goblet cells 2) microvilli
2 functions of simple columnar epithelium
1) absorption 2) secretion
goblet cells secrete ____ for mucus production
mucin
location of simple columnar epithelium
1) most of digestive tract 2) oviduct
location you can find pseudostratified columnar epithelium
trachea, nasal cavity, bronci, eustachian tubes (RESPIRATORY EPITHELIUM BESIDES ALVEOLAR TISSUE (SIMPLE SQUAMOUS) - also found in epididymis
difference between pseudostratified columnar epithelium in respiratory tract and in the epididymis
epididymis has STEREOCILIA instead of cilia. They are longer and aids in semen propagation in the vas deferens.
where would you find stratified squamous epithelium WET?
lining wet surfaces–> esophagus, anus, vagina.
purpose of stratified squamous epithelium
protection from abrasion
where would you find stratified sqamous epithelium DRY?
epidermis of skin
function of DRY stratefied squamous epithelium
keratin accumulation forms a tough WATERPROOF and MICROBE proof layer on the surface of the epithelium to protect the body from heat, microbes and damaging substances``
where would you find stratified cuboidal epithelium? (5)
1) ovary follicle 2) sweat gland 3) mammary gland 4) salivary gland 5) pancreas (and some DUCTS of glands)
Function of stratified cuboidal epithelium
has protective AND secretory functions
where would you find stratified COLUMNAR epithelium
1) conjunctiva of eye 2) male urethra parts 3) parts of vas deferens 4) some ducts of larger salivary glands (parotid)
functions of stratified columnar epithelium
protection and SECRETORY functions
transitional epithelium is also called ___
urothelium
where can you find transitional epithelium
only in the urinary tract.
function of transitional epithelum
to stretch and form a stretchable lining.
in transitional epithelium, there may be thicker portions of the umbrella cells that are coupled with actin to form ___. What is this function?
forms plaques. allows it stretch and unfold and also protects against hyperosmotic urine.
purpose of cell junctions
1) adhere cells 2) communicate (gap junctions 3) seals to prevent the flow of materials
4 types of cell junctions
1) tight junctions (zonulae occludens) 2) belt desmosomes (zonulae adherens) 3) spot desmosomes (maculae adherens) 4) gap junctions (communicating junctions)
tight junctions are aka ___ ___. Cells are tightly joined by proteins called ____
aka zonulae occludens. cells held together by CLAUDINs.
purpose of tight junctions
prevent intercellular movement of moelcules and limits movement of membrane proteins.
belt desmosomes are aka ____ ____. What proteins are involved?
aka zonulae adherens. Actin and CADHERIN GLYCOPROTEINS are involved.
purpose of zonulae adherens
anchors the terminal web of actin microfilaments in one cell with the next. Provides CELL TO CELL ADHERENCE.
zonulae adherens (belt desmosomes) are often found just beneath the ___ ___
just beneath the zonulae occludens. (spot desmosomes)
___ ___, or spot desmosomes, are small round attachments between cells which involve ___ filaments, plaques such as ___ ___ or ___, and transmembrane glycoproteins called ____.
maculae adherens, or spot desmosomes, are small round attachments between cells which involve INTERMEDIATE filaments, plaques such as PLAKOPHILIN, PLAKOGLOBIN, or DESMOPLAKIN, and transmembrane glycoproteins called CADHERINS.
Purpose of maculae adherens/ spot desmosomes
provide cell to cell attachment and stability of epithelium by LINKING CYTOSKELETONS of adjacent cells (STRONG JUNCTION)
zonula ____ and ___ form a continuous ribbon around the cell apex, whereas the ___ and ___ ___ make spotlike plaques.
zonula OCCLUDENS and ADHERENS form a continuous ribbon around the cell apex, whereas the SPOT DESMOSOMES and GAP JUNCTIONS make spotlike plaques.
cell junctions are often found as ___ ___
often found as JUNCTIONAL COMPLEXES (lateral borders of columnar epithelial cells lining the intestine)
_______ are found usualyl between stratefied squamous epithelium and basal lamina
HEMIDESMOSOMES
purpose of hemidesmosomes
anchor epithelial cells to basal lamina and prevent separation of epithelium from basal lamina
hemidesmosomes use ___ instead of cadherins in their protein plaques
INTEGRINS instead.
gap junctions join adjacent cell membranes via protein complexes called ___
connexons
conformation of connexon
6 CONNEXIN proteins forming a pore
gap junctions function
allow for passage of small molecuels and ions between cells.
the ___ ___ binds epithelium to underlying connective tissue
BASEMENT MEMBRANE
2 layers of basement membrane
1) basal lamina 2) reticular lamina
3 main functions of basement membrane
1) binding and supporting epithelium 2) selective barrier for the pasage of material between epithelium and CT 3) influences growth and metabolism of epithelial cells
3 primary surface specializations of epitheliuem
1) microvilli 2) cilia 3) stereocilia
microvilli is supported by ___ filamnets linked to the cell membrane
actin filamnets
microvilli is typically seen as a ____ ___ around the apical membrane of the cell.
brush boarder
function of microvilli
increase surface area for absorption
where can you find microvilli?
prominent on cells lining digestive tract and proximal tubules in kidney
cilia is made of ______. Outline its framework
made of microtubules. 9 doublets of microtubules plus 2 central microtubules to form the framework called an AXONEME.
function of cilia
propel material along the surface of the spithelium.
where can you find cilia?
respiratory tract and female reproductive tract (oviduct)
in addition to microtubules, ___ arms connect the 9 doublets in cilia
dynein arms
the basal body at the basement of the cilia is made of ____
9 TRIPLETS of microtubules
T/F stereocilia are longer than cilia
true, but they are closely related to microvilli in the sense that they are both made of ACTIN
where can you find stereocilia
epididymis vas deferens male urethra cochlea
function of stereocilia
increase surface area of absorption
gladular epithelia synthesize a product which is stored in __ ___ and released from a cell
secretory granules
2 categories of glands
1) exocrine 2) endocrine
what do exocrine glands
secrete their NONHORMONE products vis DUCTS into a target organ or body cavity or tissue.
T/F exocrine glands can by uni or multicellular
true
how are multicellular exocrine glands classified?
1) shape of their secretory portion–> tubular or acinar 2) duct system –> simple or compound
difference between tubular and acinar secretory portions of a multicellular exocrine gland
Acinar, a grape-like form with a small lumen, or interior space; tubular, which resemble a straight tube;
3 different means of discharge of secretory product in glands
1) holocrine: dislodge from basement membrane to give rise to secretory material, thus WHOLE CELL IS LOST to give rise to secretory material. 2) apocrine: top/APICAL of cell is also lost with secretion (mammary gland) 3) merocrine: no part of the cell is lost when the secretory product is released. Seen in salivary gland
Difference between endocrine glands and exocrine glands
exocrine glands release their contents (NON HORMONES) into a duct. Endocrine glands DO NOT have ducts and release HORMONES into the blood.
goblet cells are ____ glands.
MEROCRINE glands: none of the cellular components are lost when secreting mucin.
are goblet cells endocrine or exocrine
EXOCRINE. they release a NON-hormone substance (mucin), which combines with water to form mucus once its release.
are goblet cells uni or multicellular glands
unicellular. Exocrine.
What kind of gland is this? What structure? Method of discharge?
Sweat gland. Simple coiled tubular. Typically merocrine discharge (cell is not secreted)
What kind of gland is this? What is it’s structure? Method of discharge?
Sebaceous gland. Secretes oils. Structure: simple branched ACINAR. Discharge: holocrine; entire cell is secreted.
What kind gland is this? cell type? Exocine or endocrine? What does it secrete?
Goblet cell. EXOCRINE gland; secretes mucin and thus is not a hormone. Unicellular.
secreting cells and the ducts comprise the ____ of the gland. What mght support this layer?
parenchyma. There may be CONNECTIVE TISSUE STROMA in the gland that supports the parenchyma.
what are myoepithelial cells? where are they found?
cells that are associated with some acinar glands. They are contractile epithelial cells that push the gland’s secretion into the duct.
They are found in the salivary, mammary and sweat gland.
