Epithelium Note Cards Flashcards
Zonula Occludens
(S,F,L)
Structure: occluding, tight, impermeable junctions; cell membranes of adjacent cells are in contact with each other forming a web-like seal
Function: Sealing epitheleal cells together, preventing paracellular diffusion of materials, maintaining cell polarity
Location: Apical-most level of the lateral cell membrane (wraps around)
Zonula Adherens
(S,F,L)
Structure: adhesion junctions, band-like adhesion sites, close adjacent cell membranes, fuzzy plaques on cytoplasmic membrane made of actin filaments
Function: reinforcing cell-cell adhesion resisting separation between cells
Location: immediately below zona occuldens on lateral cell membrane
Desmosomes (Macula Adherens)
(S,F,L)
Structure: space ebtween cells with electron-dense lins, dense plaque of intermediate filaments on cytoplasmic membrane
Function: anchoring adjacent cells together, reinforcing cell-cell adhesion, resisting separation
Location: scattered throughout lateral membrane below zonula adherens
Gap Junctions
(S,F,L)
Structure: communicating junctions between adjacent cell membanes in close proximity
Function: allowing direct passage of signaling molecules between cells
Location: scattered throughout lateral membrane below zonula adherens
Hemidesmosomes
(S,F,L)
Structure: intracellular plauqes similar to desmosomes with intermediate filaments
Function: anchoring epithelia to basement membrane and connective tissue, resisting abrasion force to prevent separating between epithelium and connective tissue
Location: basal cell surface
Simple classifcation of cells
(S,F,L)
Structure: single layer of cells
Function: lining body cavity or glands, absorption, secretion
Location: areas that require quick transport of materials, large amounts of absorption or secretion
Stratified classifcation of cells
(S,F,L)
Structure: more than one layer of cells
Function: lining, protecting areas of the body that need more strength and resistance
Location: areas that require more protection and strength
Pseudostratified classifcation of cells
(S,F,L)
Structure: cells that appea stratfied but every cell contacts the basement membrane
Function: lining, absorption, secretion, creating current across epithelium
Location: areas that require movement of secretion or fluids, absorption and secretion
Squamous shape of cells
(S,F,L)
Structure: flat cells with thin and wide cytoplasm and nuclei
Function: fast transport of molecules across cytoplasm, or protection in many layers
Location: areas that require rapid exchange of molecules or protection in many layers
Cuboidal shape of cells
(S,F,L)
Structure: cube-shaped cells with central, spherical nuclei
Function: relatively fast absorption and secretion
Location: some exocrine and endocrine glands and ducts
Columnar shape of cells
(S,F,L)
Structure: tall cells with central to basal, oval nuclei
Function: large amount of absorption and secretion
Location: lining of the intestine and respiratory tract
Transitional epithelium
(S,F,L)
Structure: Number of layers and shape of the cells change based on the distention of the organ. Often have a “dome-like” appearance on apical surface; sometimes binucleate cells protruding out into the lumen on apical surface
Function: allowing distention an recoil of an organ
Location: urinary bladder, ureter, calyces, urethra
Keratinazation
(S,F,L)
Structure: Layer of flattened, dead cells
Function: forming a protective layer against, force friction, and dessication
Location: areas exposed to repeated and prolonged exposure to force, friction, and air (outside of the body only
Microvilli
(S,F,L)
Structure: Short, numerous cellular projections, contain actin
Function: increasing surface area of the luminal border
Location: areas the require large amount of absorption and secretion
Cilia
(S,F,L)
Structure: Specialized cellular projections with motile mechanisms (axonemes)
Function: generating movements to create current
Location: areas that require movement of fluids over the epithelium
Stereocilia
(S,F,L)
Structure: long, immotile cellular projections (have actin)
Function: increasing surface area for absoprtion and serving as mechano-receptors
Location: epididymis an special sensory epitheliun (inner ear)
Simple squamous epithelium
(S,F,L)
Structure: single layer of flattened cells
Function: rapid exchange of gas, small lipid-soluble molecules and fluid
Location: luminal lining of vessels, lung alveoli, body cavity serous lining
Simple cuboidal epithelium
(S,F,L)
Structure: single layer of cube-shaped cells
Function: relatively quick absorption and secretion
Location: kidney tubules, pancreatic acini, small ducts, thyroid follicles
Non-ciliated Simple columnar epithelium
(S,F,L)
Structure: single layer of rectangular cells
Function: large amount of absorption, secretion, protection
Location: lining of glands of majority of gastrointestinal (GI) tracts
Ciliated simple columnar epithelium
(S,F,L)
Structure: Single layer of rectangular cells with cilia on apical surface
Function: absorption, secretion, generation of current across the epithelium
Location: lining of fallopian tube
Ciliated pseudostratified columnar epithelium
(S,F,L)
Structure: Single layer of ciliated colunar cells, other types of cells intermixed
Function: absorption, secretion, generation of current across the epithelium
Location: most of respiratory tract
Keratinized stratified squamous epithelium
(S,F,L)
Structure: Thick layer of cells - flatted eosinophilic anucleate cells on apical surface, thick layer of cells below (may be in cuboidal shape on basement membrane)
Function: protection from repeated, prolonged exposure to force and friction, preventing dessication
Location: skin
Non-Keratinized stratified squamous epithelium
(S,F,L)
Structure: Thick, layer of cells with flattened, nucleated cells on apical surface (may be cuboidal on basement membrane)
Function: protection from repeated, prolonged exposure to force and friction
Location: oral cavity, esophagus, vagina, anal canal
Stratified cuboidal epithelium
(S,F,L)
Structure: Two or more layers of cuboidal cells
Function: maintaining the shape and patency of ducts
Location: interlobular and intralobular ducts
Stratified colunar epithelium
(S,F,L)
Structure: two or more layers of rectangular cells
Function: maintaing the shape and patency of larger ducts
Location: terminal ducts
Exocrine gland: Unicellular, single goblet shaped
(S,F,L)
Structure: within the lining epithelium, goblet shaped, nucleus near the bottom, clear near the top and eosinophilic on the sides; secreted directly into the lumen
Function: mucous secretion
Location: scattered withinin the lining of the epithelia of respiratory and GI tracts
Exocrine gland: Simple tubular
(S,F,L)
Structure: test-tube shaped glands with simple columnar epithelium as the secretory unit
Function: mucous secretion
Location: small and large intestine
Exocrine gland: Simple branched tubular
(S,F,L)
Structure: more than one test-tube shaped gland sharing a common duct or opening into a lumen; secretory units: simple colunar epithelium
Function: mostly mucous secreting
Location: stomach, pylorus
Exocrine gland: simple coiled tubular
(S,F,L)
Structure: long, convoluted gland; secretory unit: simple cuboidal to stratified cuboidal epithelium, large, pale staining cells; duct: stratified cuboidal epithelium, smaller, dark staining cells
Function: sweat secretion
Location: skin sweat glands
Exocrine gland: simple acinar
(S,F,L)
Structure: single, spherical gland draining into a short duct, secretory unit: simple cuboidal to columnar epithelium
Function: mucous secretion
Location: glands of litre near penile urethra
Exocrine gland: simple branched acinar
Structure: more than one spherical gland draining into a common duct; secretory units: stratified cuboidal epithelium, cells are large and vacuolated
Function: sebum secretion
Location: skin sebaceous glands
Exocrine gland: Compound tubular
(S,F,L)
Structure: More than one tubular gland and more than one duct opening into a lumen; secretory unit: simple columnar epithelium, pale-staining cells; ducts: simple columnar epithelium, dark-staining cells
Function: mucus secretion
Location: brunner glands of duodenum
Exocrine gland: Compound acinar
(S,F,L)
Structure: More than one spherical gland, more than one duct of varying size; secretory units: simple cuboidal to pyramindal, most serous secreting cells filled with secretory granules; ducts: simple cuboidal, simple columnar, stratified columnar
Function: Watery proteinaceous secretion
Location:parotid glands, pancreas, mammary glands
Exocrine gland: Compound tubuloacinar
Structure: More than one tubular and spherical gland, more than one duct of varying size; secretory units: simple columnar, simple cuboidal; demilunes (simple cuboidal columnar capped by hemispherical simple cuboidal acinar gland on ends); ducts: simple cuboidal, simple columnar, stratified columnar
Function: Mucous and serous secretion
Location: Sublingual and Submandibular salivary glands
Endocrine gland: Unicelluar
Structure: Single cells often with glandular epithleia, subnuclear secretory vesicles released into underlying connective tissue
Function: release of hormons affecting the epithelium they reside in
Location: Scattered throuhgout GI tract
Endocrine gland: cord
Structure: Plates of polygonal cells supported by reticular tissue and surrounded by abundant capillaries
Function: release of various hormones
Location:pituitary, parathyroid, and adrenal glands; islets of langerthans
Endocrine gland: follicles
Structure: Spherical secretory units lined by simple cuboidal endocrine cells filled with gelatinous colloid
Function: Storage of iodide, production and secretion of thyroid hormones
Location:Thyroid gland
