Body Membranes

Body Membranes

1. General Info

   • Two Classifications
     • connective tissue
     • epithelial membrane
   • General Function?
     • covering or lining

2. Synovial Membrane

   • Classification?
     • connective tissue
       • function?
         • connects
         • binds
         • supports
         • protects... structures of the body
   • Location?
     • joints of skeletal system
       • lines the capsules
   • Structure/Tissue Type?
     • outside...
       • thick fibrous layer
         • contains collagen primarily types I and III, which are major components of its fibrous layers
         • AKA?
           • cartilage
     • inside...
       • thin layer of simple epithelium
         • The lining of synovial joints is "not a true simple epithelium tissue", as it lacks a basement membrane and tight junctions. Instead, the inner layer, called the synovial membrane (or intima), is a thin, specialized connective tissue membrane that appears as a sheet of cells, typically only one to three cells thick, sitting on a loose or fibrous sublining. 
         • AKA?
           • synovial membrane
         • secretes?
           • synovial fluid
             • function?
               • reduces friction
               • reduces wear to the bone ends during joint movement

3. Mucous Membranes

   • Classification?
     • epithelial membrane
   • Location?
     • lines cavities open to external environment
       • Examples?
         • respiratory tract
         • digestive tract
         • urinary tract
         • vaginal tract
   • Structure/Tissue Type?
     • The mucous membrane, or mucosa, is composed of an epithelial layer and an underlying layer of loose connective tissue.  Epithelium: The top layer of cells. Basement Membrane: A thin, acellular, extracellular matrix layer that lies beneath the epithelium and separates it from the underlying connective tissue. Lamina Propria: The layer of loose connective tissue found directly beneath the basement membrane. 
     • simple epithelial layer
       • attached to...
         • The thin basement membrane of a mucous membrane is formally called the basal lamina when referring to the layer produced by the epithelial cells, and it sits on top of the connective tissue layer known as the lamina propria.
         • thin basement membrane
   • Secretes?
     • mucus
       • https://my.clevelandclinic.org/health/body/23930-mucosa
       • function?
         • "The mucosa functions primarily as part of your body’s immune system". It provides a barrier against foreign particles, captures them in its sticky mucus and clears them out. Immune cells and natural antibiotics in the mucus defend against pathogens, while the lubrication defends against injury. In your stomach and bladder, the mucosa protects from the abrasive effects of your body’s own stomach acid and urine. In your uterus, the mucosa (called the endometrium) thickens to protect new eggs and sheds to clear out unfertilized eggs. In some places, the mucosa also absorbs. For example, it helps break down odors in your nose and nutrients in your digestive system.
         • protection
           • in respiratory tract?
             • traps pathogens and facilitates moving them out of the body
           • digestive, urinary and vaginal tract?
             • prevents wear and erosion
               • how?
                 • regenerates quickly
                   • epithelial tissue regenerates quickly because of its high rate of cell division and the presence of stem cells. This rapid turnover is necessary to replace cells lost through abrasion and damage, but the speed varies by location, with some epithelia renewing in a matter of days while others take months.  Factors affecting regeneration speed High rate of cell division: Epithelial cells frequently undergo cell division, allowing damaged cells to be replaced quickly. Stem cells: Stem cells in the lower layers of the tissue divide constantly to produce new cells. Location: The speed of regeneration depends on the specific epithelial tissue. Intestinal lining: Can completely renew within about 5 days. Skin (epidermis): Takes around 4 weeks to renew. Lung: Can take as long as 6 months to be replaced. Injury size: For small injuries, a complete repair can happen in 1 to 3 days. For larger injuries, it may take up to two weeks. Other factors: The process also depends on factors like nutrition, inflammation, and the body's overall healing response

4. Serous Membranes

   • https://louis.pressbooks.pub/medicalterminology/chapter/cavities-and-membranes/
   • Classification?
     • epithelial membrane
   • Location?
     • in body cavities that do not open to the external environment
       • abdominopelvic cavity
       • thoracic cavity
   • Structure/Tissue Type?
     • single epithelial layer attached to...
       • thin basement membrane
     • Two distinct layers
       • https://anatomytool.org/content/openstax-anatphys-fig117-serous-membrane-english-labels
       • parietal layer
         • lines the cavity
       • visceral layer
         • covers the organs
   • Secretes?
     • serous fluid
       • function?
         • reduce friction between two layers
           • allow for smooth expansion, contraction, and movement of organs
   • Different Locations and Names?
     • thoracic cavity
       • pleura
     • abdominopelvid cavity
       • peritoneum
     • Pericardial cavity
       • pericardium

5. Cutaneous Membrane

   • Classification?
     • epithelial membrane
   • Location?
     • body's outer covering (skin)
   • Structure/Tissue Type?
     • stratified layer of epithelial tissue attached to...
       • think layer of connective tissue
   • Function?
     • Protection against...
       • invading organisms
       • environmental contaminants