Modified Stratified Squamous Epithelium

Epithelial Tissues

• Modified Stratified Squamous Epithelium

  • Keratinized Type: Surface cells are dead, filled with keratin.
  • Nonkeratinized Type: Found in mouth, esophagus, ureters, bladder, urethra; surface cells are alive and lack keratin.

• Pseudostratified Columnar Epithelium

  • Appears stratified but is a single layer of columnar cells of varying heights.
  • Can include cilia and mucus-secreting cells.
  • Lines upper respiratory passages; functions in mucus secretion and ciliary propulsion.

Basement Membrane

• Composed of a thin, acellular layer between epithelium and underlying connective tissue.
• Basal Lamina: Includes Lamina lucida and Lamina densa.
• Reticular Lamina: Composed of reticular fibers, aiding in support structure.

Connective Tissue

• Extracellular Matrix (ECM): Gel-like substance that fills spaces between cells and fibers; contains fibers and ground substance.

• Types of Fibers:

  • Collagen Fibers: Strongest, long and thin to form networks.
  • Elastic Fibers: Provide elasticity to tissues.

• Cell Types:

  • -blast: Matrix-secreting cells.
  • -cyte: Mature cells.

• Composition:

  • 10% large organic molecules and 90% interstitial fluid.
  • Contains glycosaminoglycans (GAGs) such as hyaluronic acid and proteoglycans for structural support.

Types of Connective Tissue

• Proper Connective Tissue: Divided into loose and dense categories.
  • Loose Connective Tissue:
    • Areolar: Forms lamina propria in mucous membranes.
    • Adipose: Provides cushioning, insulation, and energy storage.
    • Reticular: Supports blood cells in lymphoid organs (e.g., lymph nodes, spleen).
  • Dense Connective Tissue:
    • Dense Regular: Parallel fibers resist tension; found in tendons and ligaments.
    • Dense Irregular: Fibers arranged in multiple directions; found in dermis.
    • Elastic: High proportion of elastic fibers for recoil; found in large arteries.

Cartilage in Skeletal System

• Cartilage Composition: Dense connective tissue with chondrocytes housed in lacunae.
• Lacks nerve fibers and is avascular.
• Types of Cartilage:
  • Hyaline cartilage provides support with flexibility.
  • Elastic cartilage offers shape and elasticity.
  • Fibrocartilage absorbs shock and resists compression.

Mucous Membranes (Mucosa)

• Line cavities open to the exterior (e.g., respiratory, digestive, urinary, reproductive tracts).
• Consist of epithelial tissue with goblet cells producing mucus.
• Functions include trapping pathogens, lubrication to reduce friction, and moisture retention.

Serous Membranes (Serosa)

• Line closed body cavities.
• Composed of mesothelium resting on connective tissue; secretes serous fluid to reduce friction.
• Major types include pericardium, pleural, and peritoneum.
• Named based on location and type, such as visceral and parietal layers.

Glands

• Classification:
  • Exocrine Glands: Secrete products through ducts onto epithelial surfaces (e.g., sweat glands).
    • Multicellular Exocrine Glands: Classified as simple or compound based on duct structure; secretory parts can be tubular or alveolar.
    • Unicellular Glands: Goblet cells, single-celled and mucus-secreting.
  • Functional Types:
    • Merocrine Glands: Secrete products via exocytosis, maintaining cell integrity (e.g., salivary glands).
    • Holocrine Glands: Entire cells rupture to release products (e.g., sebaceous glands).

This quiz examines the characteristics of modified stratified squamous epithelium, focusing on both keratinized and nonkeratinized types. It covers the structural features and functions of these epithelial cells in various body locations, such as the mouth, esophagus, and bladder.