3.3 Membranes

• What are the four types of epithelial membranes?

  Mucous, serous, cutaneous, and synovial membranes
• What are the characteristics of mucous membranes?

  • Moist and line passageways that open to the exterior
  • Form a barrier against pathogens
  • Lubricated by mucus or glandular secretions
  • Contain lamina propria that supports blood vessels and nerves
• What is the function of the lamina propria in mucous membranes?

  It connects the epithelium to underlying structures and supports blood vessels and nerves
• What are examples of mucous membranes?

  Simple columnar epithelium of the digestive tract, stratified squamous epithelium of the oral cavity, and transitional epithelium of the urinary tract
• What are the characteristics of serous membranes?

  • Line body cavities that lack openings to the exterior
  • Minimize friction between opposing surfaces
  • Consist of mesothelium supported by areolar connective tissue
• What are the three types of serous membranes?

  Pleura, peritoneum, and pericardium
• What is the primary function of serous membranes?

  To minimize friction between the surfaces of organs and body walls
• What is the fluid formed on the surfaces of a serous membrane called?

  Transudate
• What happens to the volume of transudate after an injury?

  The volume may increase dramatically, complicating medical problems
• What are the characteristics of the cutaneous membrane?

  • Covers the body surface
  • Consists of keratinized stratified squamous epithelium
  • Underlying layer of areolar connective tissue reinforced by dense connective tissue
  • Thick, relatively waterproof, and usually dry
• What is the function of synovial membranes?

  • Line and lubricate joint cavities
  • Consist of areolar tissue covered by squamous or cuboidal cells
  • Regulate the composition of synovial fluid
• What distinguishes synovial membranes from other epithelial tissues?

  They have no basement membrane and an incomplete cellular layer
• What is the role of phagocytic cells in synovial membranes?

  To remove cellular debris or pathogens that could disrupt joint function
• What are the two forms of embryonic connective tissues?

  • Mesenchyme
  • Mucoid connective tissue (Wharton's jelly)
• What is mesenchyme?

  The first connective tissue to appear in the developing embryo
• What is the function of mucoid connective tissue?

  It is a loose connective tissue found in many regions of the embryo, including the umbilical cord
• What is the role of adult connective tissues containing mesenchymal cells?

  • Assist in repairs after connective tissue injury or damage