BHSC 0100 Module 3 Tissues.doc - BCIT, Basic Health...

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BCIT, Basic Health SciencesBHSC 0100Human BiologyModule 3a: TissuesA. WHATISATISSUE?ATISSUEis a group of similar cells, usually with a common embryonic origin, thatfunction together to carry out specialized activities.HISTOLOGYis the science that deals with the study of tissues.The major tissue types areEPITHELIAL,CONNECTIVE,MUSCULAR, andNERVOUS.B. EPITHELIALTISSUEDESCRIPTION OF EPITHELIAL TISSUEcovers body surfaces; lines body cavities, hollow organs, and ducts (tubes)and forms glands2 major categories of epithelial tissue1.covering and lining: layers of cells covering internal or externalsurfaces (eg. epidermis, lining of airways).Lining epitheliumfaces alumen such as in blood vessels and lymphatics (endothelium),digestive tract, urinary tract, large internal body cavities such aspleural, pericardial, peritoneal (mesothelium).2.glandular epithelium:structures that produce secretions (eg. Liver,pancreas made up predominantly of epithelium)GENERAL FEATURES OF EPITHELIAL TISSUEConsists of closely packed cells with very little extracellular matrix betweencells, often forming continuous layeravascular (no blood vessels)lies on top of highly vascularized connective tissuereceives nutrients by diffusion from the connective tissue layer.Onlythose epithelial cells close to the basement membrane receive enoughnutrients enabling them to divide to regenerate the epithelial layer(s)contains a nerve supply (i.e. sensory nerves found in the skin)have a high capacity for renewal by cell divisionfound in areas of high wear and tear, therefore they must be mitoticallyactivecancer that develops from epithelium is called a carcinoma.epithelial cells and tissue is polarizedRevised7/26/171
BCIT, Basic Health SciencesBHSC 0100Human Biologyapical surface –the free surface exposed to a body cavity, lining aninternal organ, or on the exterior of the bodybasal surface– attached to the basement membranelateral surface– faces adjacent cells on either sidein stratified epithelium, theapical layerrefers to the superficial cell layer,while thebasal layerrefers to the deepest cell layer.Tissue types differ in the number of cell layers and in the shape of the cellin the apical layerEpithelial cells also show intracellular polarizationlocation of organelles within cells have a polarizationmost prominent in columnar epitheliumnuclei are basally locatedGolgi is generally located between nucleus and apical surface(supranuclear position)

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Term
Summer
Professor
Terence Morris
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