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4.6A: Epithelial Membranes

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    7400
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    The mucous membranes are linings of mostly endodermal origin, covered in epithelium, which are involved in absorption and secretion.

     

    LEARNING OBJECTIVES

     

    Describe the function of mucous membranes

     

    KEY TAKEAWAYS

    Key Points

     

    • The mucous membranes are linings of ectodermal origin. It consists of an epithelium layer and an underlying lamina propria of loose connective tissue.
    • The mucus membranes are involved in absorption and secretion.
    • Most mucosal membranes contain stratified squamous or simple columnar epithelial tissue types.
    • Submucosal exocrine glands secrete mucus to facilitate the movement of particles along the body’s various tubes, such as the throat and the intestines.

     

    Key Terms

     

    • mucous membrane: Linings of cavities that are exposed to the external environment and to internal organs.

    The mucous membranes are linings of ectodermal origin. It consists of an epithelium layer and an underlying lamina propria of loose connective tissue. These mucus membranes are involved in absorption and secretion.  They line cavities that are exposed to the external environment and internal organs. These membranes exist in the  hollow organs of the digestive, respiratory, and urogenital tracts.

    The term “mucous membrane” refers to where they are found in the body; not every mucous membrane secretes mucus. Secreted mucous traps the pathogens in the body, preventing any further progression of  microbes.

    Most mucous membranes contain stratified squamous or simple columnar epithelial tissue. The epithelial tissue sheet lies directly over the layer of loose connective tissue called lamina propria. In some mucosa, the lamina propria rests on a deeper, third layer of smooth muscle.

    The submucosa is the tissue that connects the mucosa to the muscle outside the tube. Submucosal glands consist of exocrine glands that secrete mucus. These glands excrete mucus to facilitate the movement of particles along the body’s various tubes, such as the throat and intestines. The submucosal glands are a companion to unicellular goblet cells, which also produce mucus, and are found lining the same tubes.

    This is a chart showing the general organization of the gastrointestinial tract. The chart illustrates mucosa in the body in relation to other lining components as four boxes. The bottom box on the chart is labeled Serosa or Adventitia. The box above it is labeled Muscularis Propia and this is related to circular muscle, Auerbach's (Myenteric) Plexus, and longtitudinal muscle. The their box above is labeled Submucosa and is related to Meissner's (Submucosal) Plexus. The top box is labeled Mucosa and relates to the epithelium, lamina propria, and muscularis mucosa.

     

    General organization of the gastrointestinial tract: Illustration of mucosa in relation to other lining components.