Provides anchoring of adj. cells to one another and provides cytoplasmic continuity b/w cells
Tight Junctions (Zona Occludens)
Seal cell-lined compartments; Prevent water soluble molecule from passing through b/w cells; fuse adj. plasma membranes; Maintains polarity of cell; Disrupted by reduction of calcium concentration
What are the two types of Adhesive junctions?
Zonula Adherens & Desmosomes. Hemidesmosomes not in terminal bar
Zonula Adherens
Membrane proteins CADHERIN of adj cells bind to adhere cell to each other and the actin microfilaments in cell cortex anchor adherin proteins
Desmosomes
Are disc shaped and Cytoplasmic Intermediate Filaments anchor the adherin family membrane proteins that bind the cell
Hemidesmosomes
Found in basal layer of cells. Use INTEGRIN proteins to attach cell to extracellular matrix
Gap Junctions
Not found in terminal bar. Does not hold cells together. Allows for passage of ions & small molecules b/w adj. cells. Cells connected by connexons made of protein Connexin. Imp. in cardiac & smooth muscle=mult. cells act as one
What are the 3 types of junctions found in the terminal bar?
To incr. surface area and to move substances across cell surface
Microvilli
Covered w/ glycocalyx; Forms striated border; Found on apical surface of absorptive cells; Core of ACTIN filament helps maintain cell shape; NOT Motile only incr. surface area
Stereocilia
Long branched microvilli; Incr. surface area for TRANSPORT across membrane
Cilia
Motile; aka Axoneme (gen. term for cilia and flagella) Move material through the surface of cell & move cell through its environ. Composed of tubulin; requires ATP energy; motor protein is axonemal dynein
What is the structural composition of cilia & Microvilli?
