Extracellular Structures

Extracellular Structures

1. Cell walls

   • Plants, fungi, prokaryotes (some protists) only! Keeps it @ happy medium concerning water uptake, Protection:
   • Cellulose
     • Makes up cell wall; Dotted with polysaccharides and proteins
   • Primary Cell Wall
     • Thin and flexible, 
     • Middle Lamella
       • In-between layer, Main wall between cell's cell neighbors.
       • Secondary Cell Wall
         • Not all cells have this! Added layer between plasma membrane and primary cell wall
   • Plasmodesmata
     • "Streets" for cell's neighborhood of cells

2. Extracellular Matrix

   • Animal cells only!
   • Glycoproteins
     • Collagen, proteoglycans, and fibronectin.
   • Function
     • Support Adhesion Movement Regulation Communication for cells
   • Intercellular Junctions
     • Plasmodesmata
       • Tunnels going through hard plant cell walls
       • Allows for solutes, water, proteins and RNA to get from cell to cell.
       • Keeps things inside and things outside ; prevents organisms from going "spetic".
     • Tight Junctions
       • Cells are touching each other this point! Keeps them from leakaging extracellular "slime" 
       • Blood-brain barrier
       • Epithelia (intestine)
     • Desmosomes
       • Sheet-shaped fasteners that keeps cells together
       • Aka. anchoring junctions
       • Cardiovascular tissue
     • Gap Junctions
       • Tunnels for cytoplasm to get to neighboring cells
       • Aka. communicating junctions
       • import --> regulates what is going in and out; can open and close; helps to take in + expel waste
       • Skeletal muscle
     • Function
       • To make physical contact with other cells in tissues, organs or organ systems in communication.