Membrane mucous layer

Lamina propria None A portion of the mucous membrane, a layer of tissue found under the epithehum contains lymphoid tissue... 

FIGURE 2 Cell types of nasal epithelium showing ciliated cell (A), nonciliated cell (B), goblet cell (C), gel mucous layer (D), sol layer (E), basal cell (F), and basement membrane (G). (Reproduced from ref. 5 with permission of Pharmaceutical Press.)... 

For solutes that exhibit marginal (or a lack of) membrane affinity, permeability is low, resulting primarily from paracellular diffusion of the solute. As the propensity of the solute to partition into cell membrane increases, so does the permeability, as a result of the significant increase in surface area of the transcellular pathway relative to the paracellular route. This increase in permeability will approach a plateau, the so-called aqueous boundary layer-limited situation, in which diffusion across the cell is very rapid relative to diffusion of the solute through the unstirred water/mucous layer. 

Figure 7.1 Schematic of olfactory neurons and simplified version of receptor-containing membrane. Stimulant diffuses through mucous layer to bind to molecular receptor. Threshold occupation of molecular receptors on cilia of neuron result in membrane depolarization. (Reprinted by kind permission of Elsevier Science Publishers, B.V., Amsterdam).

Figure 2 Depiction of some components of the vertebrate olfactory epithelium in the nose. Odorants, e.g., carvone, deposit themselves in the mucous layer and interact with molecular receptors in the membrane of cilia of the olfactory receptor cells. Subsequent to intracellular signal transduction events, action potentials are sent via the olfactory axons to the olfactory bulbs in the brain. Supporting cells provide physical and physiological support for the olfactory neurons. Undifferentiated basal (stem) cells are the source of new supporting and olfactory receptor cells.

Mund-loch, n, mouth, orifice (Expl.) fuse hole, -schlcht, /, chemical layer (in a gas mask), -schleim, m. oral mucus, -schlelmhaut, /. mucous membrane of the mouth, -speichel,... 

Dru may be applied to the skin and mucous membranes using several routes topically (on the outer layers of skin), transdermally through a patch on which the drug has been implanted, or inhaled through the membranes of the upper respiratory tract. 

Mucosa. The innermost layer of the wall is the mucosa, which consists of a mucous membrane, the lamina propria, and the muscularis mucosa. The mucous membrane provides important protective and absorptive functions for the digestive tract. The nature of the epithelial cells lining the tract varies from one region to the next. Rapidly dividing stem cells continually produce new cells to replace worn out epithelial cells. The average life span of these epithelial cells is only a few days. The lamina propria is a thin middle layer of connective tissue. This region contains the capillaries and small lymphatic vessels that take up the digested nutrient molecules. The muscularis mucosa is a thin layer of smooth muscle. Contraction of this muscle may alter the effective surface area for absorption in the lumen. 

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