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Principles of Human Anatomy and Physiology, 11e1Chapter 4The Tissue Level of OrganizationLecture Outline
INTRODUCTIONAtissueis a group of similar cells that usually have a similarembryological origin and are specialized for a particularfunction.The nature of the extracellular material that surrounds theconnections between the cells that compose the tissueinfluence the structure and properties of a specific tissue.Pathologists, physicians who specialize in laboratory studiesof cells and tissues,aid other physicians in makingdiagnoses; they also perform autopsies.
Principles of Human Anatomy and Physiology, 11e3Chapter 4The Tissue Level ofOrganizationHistologythe study of tissues
TYPES OF TISSUES AND THEIR ORIGINSFour principal types based on function and structureEpithelial tissuecovers body surfaces, lines hollow organs, body cavities,and ducts; and forms glands.Connective tissueprotects and supports the body and its organs, bindsorgans together, stores energy reserves as fat, andprovides immunity.Muscle tissueis responsible for movement and generation of force.Nervous tissueinitiates and transmits action potentials (nerve impulses)that help coordinate body activities.
Origin of TissuesPrimary germ layers within the embryoendodermmesodermEctodermTissue derivationsepithelium from all 3 germ layersconnective tissue & muscle from mesodermnerve tissue from ectodermTable 29.1provides a list of structures derivedfrom the primary germ layers.
DEVELOPMENTNormally, most cells within a tissue remain in place,anchored toother cellsa basement membranesconnective tissuesExceptions include phagocytes and embryonic cells involvedin differentiation and growth.
BiopsyRemoval of living tissue for microscopic examinationsurgeryneedle biopsyUseful for diagnosis, especially cancerTissue preserved, sectioned and stained before microscopicviewing
CELL JUNCTIONSCell junctionsare points of contact between adjacentplasma membranes.Depending on their structure, cell junctions may serve oneof three functions.Some cell junctions form fluid-tight seals between cells.Other cell junctions anchor cells together or toextracellular material.Still others act as channels, which allow ions andmolecules to pass from cell to cell within a tissue.
CELL JUNCTIONSThe five mostimportant kinds ofcell junctions aretight junctions,adherensjunctions,desmosomes,hemidesmosomes,and gap junctions(Figure 4.1)
Principles of Human Anatomy and Physiology, 11e10Cell JunctionsTight junctionsAdherens junctionsGap junctionsDesmosomesHemidesmosomes
Principles of Human Anatomy and Physiology, 11e11Tight JunctionsWatertight seal between cellsPlasma membranes fused witha strip of proteinsCommon between cells that lineGI and bladder
Principles of Human Anatomy and Physiology, 11e12Adherens JunctionsHolds epithelial cells togetherStructural componentsplaque = dense layer of

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