BIOL 1410 Lecture Notes - Basement Membrane, Thyroid, Reticular Fiber
18 Dec 2013
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Proteins on lateral surfaces/sides of cells fused together. Prevents material passing between cells: anchoring junctions. Allow tissue to change shape without tearing (ex. within skin cells: gap junctions. Fasten cells to each other or to extracellular material (rivets) Lets ions/small molecules to pass from 1 cell to another. Basement membrane (can"t see it): extracellular layer: attaches epithelium to underlying ct (formed by both tissues/velcro) Simple: 1 layer: exchange of molecules (gases, nutrients, etc. , absorption, secretion (lungs/kidney) Stratified: more than 1 layer: protective (areas of wear and tear, for stratified tissues we only look at top layers (apical layer) for cell shape. Pseudo stratified = simple: appears stratified (nuclei at different levels, all cells sit on basement membrane, most of respiratory tract + ciliated. Transitional: cell shape (and layering) varies with stretching. Inner lining of urinary system: cuboidal to squamous when stretched. Cells far apart separated by extracellular matrix. Unstructured material surrounding extracellular fibers and cells.
