Tissues

Cards (150)

  • Tissue: is a group of cells with similar structure and function, along with extracellular substances located between cells.
  • Changes in tissues can result in development, growth, aging, trauma, or disease.
  • Histology: is the microscopic study of tissue structure
  • Epithelial: covers and protects surfaces, both outside and inside the body.
  • Connective: provides support, protection, and binds other tissues together. A diverse primary tissue type that makes up part of every organ in the body.
  • Muscle: allows movement by contracting to shorten or lengthen.
  • Nervous: transmits information throughout the body through electrical impulses. Responsible for coordinating and controlling many body activities.
  • EPITHELIAL TISSUE: Mostly composed of cells with very little extracellular matrix between them.
  • EPITHELIAL TISSUE: covers body surfaces that include the exterior surface, lining of digestive, urinary, reproductive, & respiratory tracts, heart & blood vessels, and linings of body cavities.
  • Distinct epithelial cell surfaces:

    • Free / Apical Surface – exposed & not attached to other cells.
    • Lateral Surface – cells attached to other epithelial cells.
    • Basal Surface – attached to a basement membrane (a specialized type of extracellular material that helps attach the epithelial cells to the underlying tissues and plays an important role in supporting & guiding cell migration during tissue repair.)
  • Major Functions of Epithelia:

    • Protecting underlying structures
    • Acting as a barrier
    • Permitting the passage of substances
    • Secreting substances
    • Absorbing substances
  • CLASSIFICATION OF EPITHELIUM:

    • Simple
    • Stratified
    • Pseudostratified
    • Transitional
  • Simple: one layer of cells only
  • Stratified: more than one layer of cells
  • Pseudostratified: special type of simple epithelium; appears to be stratified but is not
  • Transitional: modification of stratified epithelium that can be greatly stretched
  • Shape of cells (Simple):

    • Squamous
    • Cuboidal
    • Columnar
  • Shape of cells (Stratified)

    • Squamous
    • Nonkeratinized (moist)
    • Keratinized
    • Cuboidal
    • Columnar
  • Shape of cells (Transitional):

    • Roughly cuboidal to columnar when not stretched and squamous-like when stretched.
  • Simple Squamous: 1 layer of flat, tile-like cells, often hexagonal cells
  • Simple Cuboidal: 1 layer of square-shaped cells
  • Simple Columnar: 1 layer of tall, narrow cells
  • Pseudostratified Columnar: 1 layer of tall, narrow cells, appears stratified but isn’t, almost always ciliated
  • Stratified Squamous: many layers of flat, tile-like cells
  • Stratified Cuboidal: many layers, cube-shaped; relatively rare
  • Stratified Columnar: many layers, but only the surface cells are columnar; deeper layers are irregular or cuboidal in shape; relatively rare
  • Transitional: special type that changes shape
    • stretched: squamous
    • not stretched: cuboidal
  • Simple epithelium is involved with diffusion, secretion, or absorption.
  • Stratified epithelium serves a protective role.
  • Squamous cells function in diffusion or filtration.
  • Cuboidal or columnar cells, which contain more organelles, secrete or absorb.
  • Microvilli: increase cell’s surface area (ex: small intestines)
  • Cilia: move materials across cell’s surface (ex: trachea)
  • Goblet Cells: produce mucus (ex: stomach)
  • Tight Junctions: bind adjacent cell together
  • Desmosomes: mechanical links that bind cells
  • Hemidesmosomes: bind cells to basement membrane
  • Gap Junctions: most common; small channels that allow molecules to pass between cells & allow cells to communicate
  • Glands: structures that secrete substances onto a surface, into a cavity, or into blood; primarily composed of epithelium, with a supporting network of connective tissue.
  • Exocrine: type of gland with ducts (ex: sweat & oil glands)