Chapter 3: Epithelial Tissues Flashcards
covering, lining, and protecting surfaces; absorption; secretion; contractility; sensory
Principal Functions of epithelial
a thin, extracellular sheet of macromolecules; a semipermeable filter for substances reached epithelial cells from below
Basement Membrane
thin, electron-dense sheetlike layer of fine fibers; nearest to epithelial cells
Basal lamina
a more diffuse and fibrous layer; farther from epithelial tissues
Reticular lamina
self-assemble into a 2D network of mesh sheets
Type IV Collagen
large glycoproteins that attach to transmembrane integrin proteins; form “lace-like” sheets
Laminin
short, rodlike protein and proteoglycan that cross-link laminins to type IV collagen
Nidogen and Perlecan
more diffuse meshwork of the reticular lamina contains _________
Type III Collagen
composed of the cells responsible for the organ’s specialized functions
Parenchyma
the cells of which have a supporting role in the organ
Stroma
the connective tissue tat underlies the epithelia lining the organs of the digestive, respiratory, and urinary systems
lamina propria
small evaginations that project from the connective tissue into the epithelium to increase contact between the two tissues
papillae
another name for tight junctions
zonula occludens
another name for adhering junctions
zonula adherens
another name for desmosomes
macula adherens
form a seal between adjacent cells
tight junctions
are sites for strong cell adhesion; firmly anchoring a cell to its neighbors
adherent junctions
are channels for communication between adjacent cells
gap junctions
a term that indicates that the junction forms a band completely encircling each cell
zonula
the two transmembrane proteins that create the tight seal of tight junctions
occludin and claudin
transmembrane glycoproteins that mediate cell adhesion of zonula adherens
cadherins
cadherins bind _____ that link to actin filaments with actin-binding proteins
catenins
the actin filaments linked to the adherens junctions form part of the _________, a cytoskeletal feature at the apical pole in many epithelial cells
terminal web
the transmembrane proteins of desmosomes
desmogleins and desmocollins
desmoplakins bind to ____________ rather than actin filaments
intermediate filaments
transmembrane gap junction proteins
connexins
on the basal epithelial surface, cells attach to the basal lamina by anchoring junctions called
hemidesmosomes
the clustered transmembrane proteins that indirectly link to cytokeratin intermediate filaments for hemidesmosomes are
integrins
in epithelia specialized for absorption the apical cell surfaces are often filled with an array of projecting ___
microvilli
microvilli are supported by ___
microfilaments
increase the cell’s surface area, facilitating absorption; found in the epithelial cells lining the male reproductive system and inner ear sensory cells
stereocilia
long, highly motile apical structures containing internal arrays of microtubules
cilia
9+2 assembly of microtubules
axoneme
epithelial cells that function mainly to produce and secrete various macromolecules may occur in epithelia with other major functions or comprise specialized organs called ____
glands
secretory cells that synthesize, store, and release proteins are found in the
pancreas
secretory cells that synthesize, store, and release lipids are found in the
adrenal and sebaceous glands
secretory cells that synthesize, store, and release complexes of carbohydrates and proteins are found in the
salivary glands
unicellular gland that secretes lubricating mucus that aids the function of the small intestine and respiratory tract
goblet cells
secretory cells that have little synthetic activity and secrete mostly water and electrolytes (ions) are found in
sweat glands
glands that remain connected with the surface epithelium, the connection forming the tubular ducts lined with epithelium that deliver the secreted material where it is used
exocrine glands
glands that lose the connection to their original epithelium and therefore lack ducts
endocrine glands
ducts not branched
simple gland
ducts with two or more branches
complex gland
either short or long and coiled
tubular secretory portion
round and saclike
acinar secretory portion
involves typical exocytosis from membrane-bound vesicles or secretory granules; most common method of protein or glycoprotein secretion; no cell is lost
merocrine secretion
accumulate product continuously as they enlarge and and rupture, releasing the product and cell debris into the gland’s lumen; whole cell is lost
holocrine secretion
product accumulates at the cell’s apical ends, portions of which are then pinched off to release the product surrounded by a small amount of cytoplasm and cell membrane; top of cell is lost
apocrine secretion
these cells stain intensely with basophilic or acidophilic stains because they synthesize proteins
serous cells
these cells stain well with PAS as they contain heavily glycosylated proteins
mucous cells
