Lecture 2 Epithelium Flashcards
Actin microfilaments
Core of microvilli
Determine cell shape forming a gel like network
Cell motility
Contractile ring for cell division
Form stress fibers that are under tension and are contractile
Intermediate filaments
Stable tissue specific proteins
Maintain cell integrity by linking intracellular junctions
Keratins
Microtubules
Hollow Tubulin units Help polarize the cell organelles Intracellular movement Mitotic spindle Core of cilia Dynein retrograde energy source Kinesin anterograde energy source
Dynein
Retrograde actin of vesicles back toward the nucleus
Energy source
Kinesin
Anterograde motor, away from the microtubule organizing center
Types of junctions
Tight (occluding) Cell to cell anchoring (adherens- actin bundle with the next cell) (Desmosome- intermediate filament with the next cell) Cell to matrix anchoring (hemidesmosomes- intermediate filaments to ECM) Gap junction (allows
Tight junction
Zonula occludens
Semipermeable barrier
Acts as the dense between apical and basolateral membranes
Linked to actin filaments by claudin/occludin
Zonula adherens
Lateral domain
Provides adhesion between epithelial cells, reinforces tight junctions
Linked to actin filaments in the terminal web by CADHERIN
CADHERIN
Calcium dependent adhesion molecules
Link the actin filaments in the terminal web in zonula adherens
Desmosome (macula adherens)
Lateral domain
Anchors intermediate filaments
Linked by CADHERIN adhesion molecules
Electron dense area in the EM due to CADHERIN
Hemidesmosomes
Links cells to matrix
Utilizes integrins linked to intermediate filaments
Asymmetrical
Focal adhesion
Links cell to matrix
Utilizes integrin adhesion molecules linked to actin filaments
Detect changes in ECM convert them into biochemical signals
Gap junction
Form connexon Chanels that permit cell to cell communication of small ions and second messengers
No link to anchor proteins, no cytoskeletal affiliation
Gap junctions are much longer than tight junctions
