WEEK 2 -Tissues.pdf - EXCI 253: HUMAN ANATOMY TISSUES...

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EXCI 253: HUMAN ANATOMYTISSUES
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TISSUESThe study of tissues and how they form organs is calledHISTOLOGYThe cells that form each tissue have a similar structure,function, and embryonic (germ) originTISSUESmay be solid (bone), semi-solid (fat), soft(muscles, ligaments), or liquid (blood)
TISSUE TYPES1.EPITHELIAL (Epithelium)2.CONNECTIVE3.MUSCULAR4.NERVOUS
TISSUESAll body tissues are derived from the embryonicconnective tissueMESENCHYMEThe 3 “Embryonic” or “Germ” layers that develop from thisare:ECTODERMENDODERMMESODERM
“TUBE WITHIN A TUBE”The embryo differentiates (divides) into three layers like a3-dimesional ballECTODERM: Basically the outer covering of the body andnervous tissueENDODERM: Will form the lining of the body anddigestive tractMESODERM: Will form “everything else”! (Includingmuscles, ligaments, cartilage, bone, blood, etc.)
TISSUES“A group of similar cells and their intercellularsubstances functioning together to perform aspecialized activity”A group of cells with acommon PURPOSEHOMEOSTASIS!
TISSUE TYPES1.EPITHELIAL (Epithelium)2.CONNECTIVE3.MUSCULAR4.NERVOUS
1. EPITHELIAL (Epithelium) TISSUE(Derived from all three germ layers, but mostly from ENDODERM)PROTECTION(Epidermis of skin)FILTRATION(Membranes for nutrient absorption)SECRETION(Release mucous, hormones, enzymes)EXCRETION(Waste products such as CO2,urine)
2 MAIN TYPES OF EPITHELIUM (by location)1. SURFACE EPITHELIUM:Lining and covering2. GLANDULAR EPITHELIUM:Secretory tissue in glandsBoth of these types of epithelium have closely packedcells (Cellularity) with hardly any extracellular material(Matrix) between the cellsTheBasement Membraneis a non-cellular layer ofmaterials which holds the epithelia to the underlyingconnective tissue (and gives strength to the epithelium)
EPITHELIUMEpithelium has no blood supply of its own = AvascularMost connective tissues doCells have a high ability to divide for repair and renewalExample: layers of skinEpithelial tissue lies close to tissues that do have bloodsupply to be able to survive and functionEpithelial tissue is rarely covered by another tissue – italways has a “free” surface
EPITHELIUMAPICAL (free) SURFACEfaces the body cavity,lumen, duct, etc.BASAL SURFACEdeepest layer (attached tothe Basement Membrane
BASEMENT MEMBRANETWO LAYERS1.BASAL LAMINA• Closer to the actual epithelial cells• Contains proteinslaminin(‘glue’ that attaches theepithelial cells to the membrance) andcollagen(forstrength)2.RETICULAR LAMINA• Closer to the underlying connective tissue• Contains collagen which is produced by connectivetissue cells (fibroblasts)
BASEMENT MEMBRANE
SHAPE OF EPITHELIAL CELLSSQUAMOUS: Flat and thinCUBOIDAL:SquareCOLUMNAR:RectangularTRANSITIONAL:Comprised of both squamous andcuboidal cells that form linings of the hollow organs.

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Term
Fall
Professor
PARIS
Tags
Stratified Cuboidal Epithelium, Lining Epithelium

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