Lecture 6: Epithelial cell specializations Flashcards Preview

Structures > Lecture 6: Epithelial cell specializations > Flashcards

Flashcards in Lecture 6: Epithelial cell specializations Deck (10):

Occluding Junctions/Tight Junctions

Separate lumen from intercellular space and maintains polarity of the cell; made of occludin/claudin proteins, Z01-Z03, AF-6 proteins


Zonula adherens

located deep to zonula occludens; forms strong bond btw adj. cells, serves as anchor for actin network; made of cadherines, cytoplasmic face actin filaments; attachment proteins- catenins, vincuin, alpha-actinin


Desmosomes (macula adherens)

Deep to adhering junctions, scattered; provide structural integrity, large number in stratified squamous, achoring for intermediate filaments (keratin/tonofilaments); inside cell -->intercellular space is filaments-->desmoplakin-->desmoglein-->desmocollin


Terminal Bar

Tight junction, zonula adherens, madula adherens all line up and form dark bar


gap junction

deep to junctional complex, serves as communication between cells, common in embryonic tissue; regulated by Ca++, pH, cAMP; composition is 6 connexin transmembrane proteins



Basal plasma membrane; anchors cytoskeleton (intermediate filaments) to basement membrane; made of integrin proteins on basement membrane and laminin-5


Functions of basement membrane

1. Physical Support
2. Cell attachment
3. Barrier that selectively lets through things
4. Growth/differentiation
5. Regeneration of above tissue
6. Special functions: ultrafiltration in kidney, blood-air barrier, tumor metastasis



Longer and thicker than microvilli
20 microtubules (tubulin), a central pair surrounded by 9 doublets, doublets connected by dynein arm, have ATPase activity; inserts into basal body in cytoplasm (9 triplets of microtubules); functions clean airway, transport of ovum, sperm tails



Thinner and shorter than cilia, actin, made of 20-30 filaments each. Covered by glycoprotein (glycocalyx) contrant/elongate, nut no active mvmnt. Create fuzzy covering on top of cells (striated border)



Long microvilli that were mistaken for cilia; found in epididymus pseudostratified columnar cells, believed to facilitate absorption and secretion, sperm transport is aided by large volumes of secretion