Ocular: cell junctions Flashcards
What is the intercellular space? why is it important?
Fluid outside of cells aka internal enviornment.
-contains extracellular fluid
-high [Na+], low [K+]
the composition determines whether cells can obtain from it what they need to produce proteins and other molecules essential for existence
What are surface specializations of the apical, lateral, and basal surface of cells? Why are they important?
Apical- free or exposed space
-microvilli
-stereocilia
-cilia
Lateral- neighboring epithelial
-occluding, adhering, and communicating junctions
Basal- surface anchored to connective tissue
-basal lamina and striations
what are the different types of cell to cell junctions?
occluding- zonula occludens
adhering- zonula adherens, desmosomes, and hemidesmosomes
communicating-gap junctions
how do cell-to-cell junctions differ and why are they important?
occludens- obliterates intercellular space, preventing passage of material between adjacent cells
Adherens-attach cytoskeletal filaments of one cell to cytoskeletal filaments of adjacent ones(CAMs)
communicating- allow for intercellular communication and electrical coupling
what is a hemidesmosome and why is it important?
-attach epithelial cells to basal lamina
- transmembrane proteins of the integrin family link the hemidesmosomes to the ECM
what are gap junctions? why are they important? what do they allow for?
-gap junctions are between adjoining cells showing the structural components of the membrane that form channels
-allow for intercellular communication and electrical coupling of cells.
-formed by transmembrane proteins called connexins
what does the basement membrane do ?
-structural attachment- flexible and firm
-compartmentalization- separate tissues
-filtration- physical and polyanionic
-tissue scaffolding
-regulation and signaling
why are basal enfoldings important?
-increase the surface area of the basal membrane, and thus the number of the ion pumps
