PNB 2264 Lecture Notes - Lecture 4: Connective Tissue, Tight Junction, Loose Connective Tissue
6 Sep 2019
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Pnb 2264 lecture 4: epithelial tissue, connective tissue. Tight junctions : prevent substances from moving between cells. Hold cells together tightly, acting like a zipper. Force substances to move through plasma membranes of cells to get through. Occurs when tight junction proteins in the stomach are broken down due to toxins in food (clostridium enterotoxin), allowing bacteria to move easily throughout the body. Adherens junctions : actin filament-based systems, go all the way through the membrane and attach on the other side. Desmosomes : act as buttons, holding cells loosely together. Allow some flexibility, which is important for cells than change in size/shape. Characterized by broken down desmosomes, creating gaps between cells in epidermis. Gap junctions : act as a door between cells, allowing communication between adjacent cells. Shapes: squamous (flat in shape), cuboidal (cubed-shaped), or. Simple (one layer) or striated (multiple layers) Pseudostratified : nuclei located in irregular positions (simple but appear.
