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Epithelial Tissue - Anatomy & Physiology

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Terms in this set (20)

  • What are the six defining characteristics of epithelial tissue?
    Cellularity, Polarity, Attachment to basement membrane, Avascularity, Sheets/layers, and Regeneration.
  • What is the functional consequence of epithelial tissue being avascular?
    Nutrients and wastes move by diffusion or absorption from underlying connective tissue.
  • What is the difference between the basal lamina and the basement membrane?
    The basal lamina is produced by epithelial cells and filters large molecules; the basement membrane includes the basal lamina plus the fibroreticular lamina anchoring it to connective tissue.
  • Name three apical specializations of epithelial cells and their functions.
    Microvilli increase surface area for absorption, stereocilia aid absorption and sensory reception, cilia move mucus or materials over the epithelial surface.
  • How are epithelial tissues classified by layers and cell shape?
    By number of layers: simple (one layer) or stratified (multiple layers); by apical cell shape: squamous (flat), cuboidal (cube-shaped), or columnar (tall).
  • What is the main function of simple squamous epithelium and where is it found?
    Thin layer suited for diffusion and filtration; found in alveoli, endothelium of vessels, and serous cavities.
  • How does keratinized stratified squamous epithelium differ from nonkeratinized?
    Keratinized has a thick dead surface layer for water resistance and protection; nonkeratinized has living surface cells and remains moist.
  • What is the structure and function of simple cuboidal epithelium?
    One layer of cube-shaped cells supporting secretion and absorption; found in kidney tubules and glands.
  • Where is stratified cuboidal epithelium found and what is its function?
    Rare; found in sweat and mammary gland ducts; provides stronger duct walls with some secretion and absorption.
  • Describe the structure and function of simple columnar epithelium.
    One layer of tall cells often with microvilli and goblet cells; supports absorption, secretion, and some protection; found in stomach and intestines.
  • What distinguishes pseudostratified ciliated columnar epithelium?
    One layer with nuclei at different heights; contains goblet cells and cilia to trap and move mucus; found in nasal cavity, trachea, and bronchi.
  • How does transitional epithelium adapt to stretching?
    Stratified with dome-shaped surface cells when relaxed and flattened when stretched; allows expansion and recoil without damage; found in urinary bladder and ureters.
  • What are the two main classes of glands and their secretion routes?
    Exocrine glands secrete through ducts onto epithelial surfaces; endocrine glands are ductless and secrete hormones into the blood.
  • What are the three types of exocrine gland secretions?
    Serous (watery, enzyme-rich), mucous (mucins forming mucus), and mixed (both serous and mucous cells).
  • How are exocrine glands structurally classified?
    By duct branching: simple (unbranched duct) or compound (branched duct); by secretory shape: tubular, alveolar/acinar, or tubuloalveolar.
  • Describe the three methods of glandular secretion.
    Merocrine: product released by exocytosis, cell intact; Apocrine: product plus apical cytoplasm shed, cell repairs; Holocrine: entire cell ruptures and dies.
  • Why is regeneration necessary in holocrine glands?
    Because secretion destroys entire cells, stem cells must replace lost cells to maintain secretion.
  • What is the master rule summarizing epithelial specialization?
    Thin epithelia specialize in exchange; cuboidal/columnar in secretion/absorption; stratified in protection; ciliated in moving surface material; transitional in stretching.
  • How can you identify epithelial tissue in histology slides?
    Find lumen or free surface, locate basement membrane, count layers, identify apical cell shape, and look for special features like cilia, microvilli, goblet cells, keratin, or ducts.
  • What is the role of respiratory cilia in pseudostratified epithelium?
    They propel mucus and trapped particles from lower respiratory passages toward the throat for clearance.