ANPH - Tissues

• Tissues: group of similar cells with common function
• Histology: study of tissues
• Pathologist: looks for tissue changes that indicate disease
• 4 Basic Tissues: Epithelial Tissue, Connective Tissue, Muscle Tissue, Nerve Tissue
• Epithelial tissue: covers surfaces because cells are in contact; lines hollow organs, cavities and ducts; forms glands when cells sink under the surface
• Connective tissue: material found between cells that supports and binds structures together; stores energy as fat and provides immunity to disease
• Muscle Tissue: cells shorten in length producing movement
• Nerve Tissue: cells that conduct electrical signals and detects changes inside and outside the body; responds with nerve impulses
• Epithelial Tissue General Features

  • Closely packed cells forming continuous sheets
  • Cells sit on basement membrane
  • Apical (upper) ree surface
  • Avascular
  • Rapid cell division
• Basement Membrane: holds cells to connective tissue
• Types of Epithelium: Covering and lining epithelium, Glandular epithelium
• Covering and lining epithelium: epidermis of skin; lining of blood vessels and ducts; lining respiratory, reproductive, urinary & GI tract
• Glandular epithelium: secreting portion of lands; thyroid, adrenal, and sweat glands
• Classification of Epithelium: by arrangement of cells into layers, by shape of surface cells
• Classified by arrangement of cells into layers

  • Simple: one cell layer thick
  • Stratified: many cell layers thick
  • Pseudostratified: single layer of cells where all cells don't reach apical surface
• Classified by shape of surface cells:

  • Squamous: flat
  • Cuboidal: cube-shaped
  • Columnar: tall column
  • Transitional: shape varies with tissue stretching
• Classification of Epithelial Tissue: Arrangement of cells in layers, Cell Shapes
• Arrangement of cells in layers: Simple Epithelium, Pseudostratified Epithelium, Stratified Epithelium
• Cell Shapes: Squamous cells, Cuboidal cells, Columnar cells, Transitional cells
• Simple Epithelium - one layer of cells
• Pseudostratified Epithelium - it appears to have multiple layers of cells because the cell nuclei lie at different levels
• Stratified Epithelium - consists of many layers of cell
• Squamous cells - flat and thin
• Cuboidal cells - cube shape
• Columnar cells - column-like
• Transitional cells - cells change shape, from squamous to cuboidal and back
• Types of Epithelial Tissues: Simple Epithelium, Stratified Epithelium
• Simple Epithelium: Simple Squamous epithelium, Simple Cuboidal Epithelium, Simple Columnar Epithelium, Pseudostratified Columnar Epithelium
• Simple Squamous Epithelium: single layer of flat and thin cells that lines blood vessels (endothelium), body cavities (mesothelium)
• Simple Squamous Epithelium: very thin --- controls diffusion, osmosis and filtration; nuclei centrally located; cells in direct contact with each other
• Simple Cuboidal Epithelium: single layer of cube-shaped cells viewed from the side; nuclei round and centrally located; functions for absorption or secretion
• Simple Columnar Epithelium: single layer of rectangular cells; unicellular glands = goblet cells secrete mucus
• Microvilli: fingerlike cytoplasmic projections
• Simple Columnar Epithelium: lubricate GI, respiratory, reproductive and urinary systems; for absorption in GI tract (stomach to anus)
• Pseudostratified Columnar Epithelium: single cell layer where all cells attach to basement membrane but not all reach free surface; nuclei at varying depths and can be found at respiratory system, male urethra & epididymis
• Stratified Epithelium: Stratified Squamous Epithelium, Stratified Cuboidal Epithelium, Stratified Columnar Epithelium, Transitional epithelium
• Stratified Squamous Epithelium: many layer of flat and thin cells; can be keratinized (surface cells dead and filled with keratin) or non-keratinized (no keratin in moist living cells at surface)
• Stratified Cuboidal Epithelium: two or more layers of cube-shaped cells
• Stratified Columnar Epithelium: layers of column-like cells
• Transitional epithelium: many layer of transitional cells that change its shape; multilayer; surface cells varying in shape from round to flat if stretched; lines hollow organs that expand from within (urinary bladder)