Chapter 4 Histology - BIO 213

• Histology


  Study of Tissues
• Biopsy


  removal of tissues for diagnostic purposes
• Autopsy


  postmortem examination of organs to determine cause of death
• Tissue classification is based off of


  structure of cells, composition of non-cellular extracellular matrix and cell function
• Epithelial


  covers internal and external surfaces of the body
• connective tissue


  connects tissue of the body
• muscle tissue


  involved in movement of body parts
• nervous tissue function


  facilitates communications between brain and other body parts
• epithelial tissue characterisitscs


  Consists of almost entirely of cells, Polar, Basement membrane

  Specialized contacts

  Avascular (doesn't have blood vessels;

  regenernate
• epithelial tissue functions


  Protection underlying structures, acting as barriers, permitting the passage of substances; secreting substances; absorbing substances
• Cell Connections


  Found on lateral and basal surfaces of cells
• Cell Connections function


  Form permeability layer

  Bind cells together

  Provide mechanism for intercellular communication
• Desmosomes


  - attach cytoskeletons of adjacent cells togetheroFound in areas that are subjected to stress;extremely strong and prevent cells from being pulled aparto Intermediate filaments extend into cytoplasm of cellso Found in stratified squamous epithelium of the skin
• Hemidesmosomes


  attach epithelial cells to basement membrane
• Tight Junctions


  hold cells together, form permeability barrier; impermeable to water; prevents passage of material between layers
• Gas Junctions


  pretin channels that aid in intercellular communication, o Allows ions and small molecules to pass through

  o Coordinate function of cardiac and smooth muscle

  o May help coordinate movement of cilia in ciliated types of epithelium
• types of layers of epithelial tissue

  simple, stratified, pseudostratified
• Simple


  one layer of cells
• stratified


  multiple layers of cells
• Psuedostratified


  o Tissue appears to be stratified but all cells contact basement membrane so it is in fact simple
• Epithelial Tissue Shapes


  squamous, cuboidal, columnar
• simple squamous epithelium


  appearance: single layer of flattened cell

  function: facilitates passage of materials across membrane; some secretion and protein against friction

  Location: lines blood vessels, lines glomerulus of kidney, forms alveoli of lungs

  
• stratified squamous epithelium


  Appearance: multiple layers of flattened cells

  Function: protection from abrasive forces

  Location: Keratinized type found in skin; non-keratinaized type found in wet surfaces of mouth, esophagus, vagina, and rectum

  
• simple cuiboidal epithelium


  Appearance: single layer of cubed-shaped cells

  Function: o absorption and/or secretion

  Location:lines the lumen of small secretory ducts, kidney tubules, portions of bronchioles, surface of the ovaries

  
• Stratified Cuboidal Epithelium


  Appearance: multiple layers of cube-shaped cells

  Function: Protection, secretion and absorption

  Location: sweat glands, mammary glands, and salivary glands

  
• simple columnar epithelium


  Appearance: single layer of tall, column-shaped cells

  Function: absorption and or/, sometimes ciliated driven movement of materials

  Location: lines the intestinal tract of lumens of some secretory ducts, lines bronchi and uterine tubes

  
• Stratified Columnar Epithelium


  Appearance: multiple layers of tall, column shaped cells

  Function: Protection, secretion of mucus

  Location: ciliated type in trachea and upper respiratory tract; non ciliated type in male reproductive tract

  
• Transitional Epithelium


  Appearance: multiple layers of round cells

  
  

  Function: allows stretching or expansion of an organ

  
  

  Location: lines the urinary bladder, urethra, and ureters
• Endocrine Glands


  no open contact with exterior, no ducts, produces hormones
• exocrine glands


  open contact maintained with exterior, ducts,
• goblet cells


  secrete mucus
• multicellular


  simple or compound
• connective tissue:


  abundant; found in every organ, consists of cells separated by extra cellular matrix
• Connective tissue functions:


  enclosed organs as a capsule and separates organs into layers, connects tissue to one another, support and movement, transport, protect, storage, cushion and insulate
• Blasts


  create matrix
• cytes


  to maintain
• clasts


  break the matrix down for remodeling
• collagen


  Most common protein in body; strong, flexible, inelastic
• Reitcular


  fill spaces between tissues and organs

  
  

  form branching networks
• elastic


  Returns to its original shape after distension or compression. Contains molecules of protein elastin that resemble coiled springs;