Tissues — Epithelium Flashcards
epithelial characteristics
free surface, closely aggregated cells, avascular
domains
apical, lateral, basal
surface specialization of apical
microvilli, sterocilia, cilia
microvilli
function to increase surface area; contains acting, actin-binding proteins (fibrin and fascin), lateral anchoring proteins (minimyosin), amorphous apex (villin)
microvilli locations
GI tract and kidneys
stereocilia
function to increase surface area; long microvilli
stereocilia locations
epididymis (absorption) and each cochlea (sensory receptors)
cilia
aids in movement; transports materials along surface; core is axoneme: 9+2 microtubules, basal body 9+0 triplets lacking central pair
cilia locations
respiratory tract and oviduct
cell junctions (lateral domain)
tight, anchoring, communicating (gap)
tight junctions—zonula occludens
belt-like junction; seal or zipper; virtually impermeable; prevents diffusion blocking paracellular pathway; occudens and claudins are the two main proteins
zonula occludens locations
stomach (cells with secretory role) and kidney (cells with absorptive role)
anchoring junctions—zonula adherens
connects actin filaments of two cells; contains actin-binding proteins, peripheral protein catenin which is Ca2+ dependent, and transmembrane protein cadherin
anchoring junctions—madula adherens
connects intermediate filaments of two cells; mechanical strength; intracellular plaque; contains transmembrane protein cadherin
madula adheren locations
skin and muscle