part 3

• Simple cuboidal epithelium


  • Involved in spaces where secretion and absorption takes place
  • Cuboidal/hexagonal boxes lined up
  • Distance between nuclei is approx height of epithelium
• Membrane modifications


  • Cells can take on different shapes
  • Epithelial cells have microvilli or a brush border that are like tiny bristles
  • Essential for non-motile cytoplasmic projections
• Brush borders


  Increase surface area for absorption
• Cilia


  • More mobile
  • Use energy to move in a particular direction
  • Transport stuff along
  • Sweep mucus along
• Simple columnar epithelium


  • Elongated
  • Tends to manufacture things
  • More metabolically active
  • Rectangular
  • Hexagonal, taller and more slender than cuboidal
  • Elongate nuclei near the base of cell
  • Height several time the distance between adjacent nuclei
  • More cytoplasm so more organelles
• Non-ciliated columnar epithelium


  • Single layer
  • Microvilli on apical surface
  • Goblet cells interspersed
• Goblet cells


  • Full of mucus
  • Get secreted on the surface to help the passage of things along those surfaces
• Ciliated simple columnar


  • Single layer and have goblet cells too
  • Cilia rhythmically beats to move material along the surface
• Stratified squamous epithelium


  • Cells form layers like plywood or pancakes
  • Lower layers cuboidal or columnar
  • Cells further from nutrition are thinner, and less active
  • Located where mechanical or chemical stresses are severe
  • Made to deal with trauma as lots of cells stacked up
  • Packed with keratin in placed where mechanical stresses and dehydration are a major issue
  • Makes surface tough and waterproof
• Non-keratinised stratified squamous epithelium


  • Cells become more and more squamous and move towards the apical surface as they die
  • Cells become flattened
• Keratanised stratified squamous epithelium


  • Keratin on the outside is stuff the used to be inside the cells
  • As cells die to get to the apical surface they leave keratin on the surface as a protective layer
  • Important in the skin
• Stratified cuboidal epithelium


  • Cuboidal-shaped cells arranged in different layers
  • Protects areas such as ducts of sweat, mammary and salivary glands
  • The lining of excretory ducts such as salivary and sweat glands
  • The main function is structural reinforcement since it is not very involved in absorption or secretion
• Stratified columnar epithelium


  • Column-shaped cells arranged in multiple layers
  • Found in conjunctiva, pharynx, anus and male urethra
  • Also occurs in embryo
  • Protects underlying tissues with multiple layers of epithelial cells
  • Perform secretion
• Stratified transitional epithelium


  • Several layers of cells that become flattened when stretched
  • Lined the urinary tract and allows the bladder to expand
  • Protects urinary system
  • Without this tissue's ability to stretch and expand, the urinary bladder would not be able to hold large quantities of urine
• Pseudostratified columnar epithelium


  • Nuclei at different levels
  • Appears to have several layers not true
  • Cells contact the basement membrane but don't reach the apical surface of tissue
  • It is just a simple epithelium
• Ciliated pseudostratified columnar epithelium


  • Secrete mucus from goblet cells
  • Found in most upper airways
• Non-ciliated pseudostratified columnar epithelium


  • Important for absorption and protection
  • Found in larger ducts of glands, epididymis, part of the male urethra