Tortora - Chapter 4 - The Tissue Level of Organization.ppt

Tortora Chapter 4 - 4-1Chapter 4The Tissue Level of Organization•Group of similar cells–common embryonic origin–common

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Unformatted text preview: 4-1Chapter 4The Tissue Level of Organization•Group of similar cells–common embryonic origin–common function•Histology–study of tissues•Pathologist–looks for tissue changes that indicate disease4-24-34 Basic Tissues (1)•Epithelial Tissue–covers surfaces because cells are in contact –lines hollow organs, cavities and ducts–forms glands when cells sink under the surface•Connective Tissue–material found between cells–supports and binds structures together–stores energy as fat–provides immunity to disease4-44 Basic Tissues (2)•Muscle Tissue–cells shorten in length producing movement•Nerve Tissue–cells that conduct electrical signals –detects changes inside and outside the body–responds with nerve impulses4-5Origin of Tissues•Primary germ layers within the embryo–endoderm–mesoderm–ectoderm•Tissue derivations–epithelium from all 3 germ layers–connective tissue & muscle from mesoderm–nerve tissue from ectoderm4-6Biopsy•Removal of living tissue for microscopic examination–surgery–needle biopsy•Useful for diagnosis, especially cancer•Tissue preserved, sectioned and stained before microscopic viewing4-7Cell Junctions•Tight junctions •Adherens junctions•Gap junctions•Desmosomes•Hemidesmosomes4-8Tight Junctions•Watertight seal between cells•Plasma membranes fused with a strip of proteins•Common between cells that line GI and bladder4-9Adherens Junctions•Holds epithelial cells together•Structural components–plaque = dense layer of proteins inside the cell membrane–microfilaments extend into cytoplasm–integral membrane proteins connect to membrane of other cell4-10Desmosomes•Resists cellular separation and cell disruption•Similar structure to adherens junction except intracellular intermediate filaments cross cytoplasm of cell•Cellular support of cardiac muscle4-11Hemidesmosomes•Half a desmosome•Connect cells to extracellular material–basement membrane4-12Gap Junctions•Tiny space between plasma membranes of 2 cells•Crossed by protein channels called connexons forming fluid filled tunnels•Cell communication with ions & small molecules•Muscle and nerve impulses spread from cell to cell–heart and smooth muscle of gut 4-13Epithelial Tissue -- General Features•Closely packed cells forming continuous sheets •Cells sit on basement membrane•Apical (upper) free surface•Avascular---without blood vessels–nutrients diffuse in from underlying connective tissue•Good nerve supply•Rapid cell division •Covering / lining versus glandular types4-14Basement Membrane•Basal lamina–from epithelial cells–collagen fibers•Reticular lamina–secreted by connective tissue cells–reticular fibers•holds cells to connective tissue•guide for cell migration during development4-154-16Types of Epithelium•Covering and lining epithelium–epidermis of skin–lining of blood vessels and ducts–lining respiratory, reproductive, urinary & GI tract•Glandular epithelium–secreting portion of glands–thyroid, adrenal, and sweat glands4-17...
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This note was uploaded on 06/11/2009 for the course BIOL 251 taught by Professor Hurrell during the Spring '09 term at Delgado CC.

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Tortora Chapter 4 - 4-1Chapter 4The Tissue Level of Organization•Group of similar cells–common embryonic origin–common

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