Principles of Human Anatomy and Physiology, 11e1Chapter 4The Tissue Level of OrganizationLecture Outline
INTRODUCTION•Atissueis 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 ofOrganization•Histology–the study of tissues
TYPES OF TISSUES AND THEIR ORIGINSFour principal types based on function and structure•Epithelial tissue–covers body surfaces, lines hollow organs, body cavities,and ducts; and forms glands.•Connective tissue–protects and supports the body and its organs, bindsorgans together, stores energy reserves as fat, andprovides immunity.•Muscle tissue–is responsible for movement and generation of force.•Nervous tissue–initiates and transmits action potentials (nerve impulses)that help coordinate body activities.
Origin 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 ectoderm–Table 29.1provides a list of structures derivedfrom the primary germ layers.
DEVELOPMENT•Normally, most cells within a tissue remain in place,anchored to–other cells–a basement membranes–connective tissues•Exceptions include phagocytes and embryonic cells involvedin differentiation and growth.
Biopsy•Removal of living tissue for microscopic examination–surgery–needle biopsy•Useful for diagnosis, especially cancer•Tissue preserved, sectioned and stained before microscopicviewing
CELL JUNCTIONS•Cell 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 JUNCTIONS•The five mostimportant kinds ofcell junctions aretight junctions,adherensjunctions,desmosomes,hemidesmosomes,and gap junctions(Figure 4.1)
Principles of Human Anatomy and Physiology, 11e10Cell Junctions•Tight junctions•Adherens junctions•Gap junctions•Desmosomes•Hemidesmosomes
Principles of Human Anatomy and Physiology, 11e11Tight Junctions•Watertight seal between cells•Plasma membranes fused witha strip of proteins•Common between cells that lineGI and bladder
Principles of Human Anatomy and Physiology, 11e12Adherens Junctions•Holds epithelial cells together•Structural components–plaque = dense layer of