mucous membrane

Examples of mucous membrane in the following topics:

• Physical and Chemical Barriers

  • Regions of the body that are not protected by skin (such as the eyes and mucous membranes) have alternative methods of defense.
  • These include tears in the eyes; mucous membranes that provide partial protection despite having to allow absorption and secretion; mucus secretions that trap and rinse away pathogens; and cilia (singular cilium) in the nasal passages and respiratory tract that push the mucus with the pathogens out of the body .
  • Some of these include the low pH of the stomach, which inhibits the growth of pathogens; blood proteins that bind and disrupt bacterial cell membranes; and the process of urination, which flushes pathogens from the urinary tract.

• Regulating Immune Tolerance

  • Mucosa are another name for mucous membranes.
  • This allows the immune system to detect and deal with pathogens very quickly after they enter the body through various mucous membranes.

• Thermoreception

  • End-bulbs are found in the conjunctiva of the eye, in the mucous membrane of the lips and tongue, and in the epineurium of nerve trunks.

• Mammalian Systems and Protective Mechanisms

  • As air crosses the surfaces of the mucous membranes, it picks up water.

• Epithelial Tissues

  • However, each cell is attached to the base membrane of the tissue and, therefore, they are simple tissues.
  • The cilia enhance the movement of mucous and trapped particles out of the respiratory tract, helping to protect the system from invasive microorganisms and harmful material that has been breathed into the body.
  • The goblet cells contain mucous that traps irritants, which, in the case of the trachea, keep these irritants from getting into the lungs.
  • Goblet cells secret mucous into the digestive tract lumen.

• Membrane Fluidity

  • The mosaic nature of the membrane, its phospholipid chemistry, and the presence of cholesterol contribute to membrane fluidity.
  • There are multiple factors that lead to membrane fluidity .
  • First, the mosaic characteristic of the membrane helps the plasma membrane remain fluid.
  • It lies alongside the phospholipids in the membrane and tends to dampen the effects of temperature on the membrane.
  • Explain the function of membrane fluidity in the structure of cells

• Components of Plasma Membranes

  • The plasma membrane protects the cell from its external environment, mediates cellular transport, and transmits cellular signals.
  • The plasma membrane (also known as the cell membrane or cytoplasmic membrane) is a biological membrane that separates the interior of a cell from its outside environment.
  • The primary function of the plasma membrane is to protect the cell from its surroundings.
  • The membrane also maintains the cell potential.
  • The cell employs a number of transport mechanisms that involve biological membranes:

• Selective Permeability

  • Plasma membranes are asymmetric: the interior of the membrane is not identical to the exterior of the membrane.
  • On the interior of the membrane, some proteins serve to anchor the membrane to fibers of the cytoskeleton.
  • This adds considerably to the selective nature of plasma membranes.
  • Polar substances present problems for the membrane.
  • The exterior surface of the plasma membrane is not identical to the interior surface of the same membrane.

• Osmosis

  • Osmosis is the movement of water through a semipermeable membrane according to the concentration gradient of water across the membrane, which is inversely proportional to the concentration of solutes.
  • Semipermeable membranes, also termed selectively permeable membranes or partially permeable membranes, allow certain molecules or ions to pass through by diffusion.
  • While diffusion transports materials across membranes and within cells, osmosis transports only water across a membrane.
  • The semipermeable membrane limits the diffusion of solutes in the water.
  • On both sides of the membrane the water level is the same, but there are different concentrations of a dissolved substance, or solute, that cannot cross the membrane (otherwise the concentrations on each side would be balanced by the solute crossing the membrane).

• The Plasma Membrane and the Cytoplasm

  • Despite differences in structure and function, all living cells in multicellular organisms have a surrounding plasma membrane (also known as the cell membrane).
  • Cholesterol, also present, contributes to the fluidity of the membrane.
  • This structure causes the membrane to be selectively permeable.
  • In the case of the plasma membrane, only relatively small, non-polar materials can move through the lipid bilayer (remember, the lipid tails of the membrane are nonpolar).
  • Explain the structure and purpose of the plasma membrane of a cell