Nerve wraps

Kokkalis, Z.T., Pu, C., Small, G.A., Weiser, R.W., Venouziou, A.I., Sotereanos, D.G., 2011. Assessment of processed porcine extracellular matrix as a protective barrier in a rabbit nerve wrap model. J. Reconstr. Microsurg. 27,19-28. 

When large areas of the membrane are depolarized in this manner, the electrochemical disturbance propagates in wave-like form down the membrane, generating a nerve impulse. Myelin sheets, formed by Schwann cells, wrap around nerve fibers and provide an electrical insulator that surrounds most of the nerve and greatly speeds up the propagation of the wave (signal) by allowing ions to flow in and out of the membrane... 

Ahead lock can be broken with one sure swiH blow. You moy frantically pull and tug and twist to release yourself from someone who has an arm tightly wrapped around your neck or by Jiu-Jitsu you may release yourself easily in less than two seconds. There is no question about the effectiveness of this method—the effect on the nerve which is struck is instantaneous ond severe. This release is very easy to apply and needs comparatively little proctice. 

Myelin—A multilayered membrane system of a Schwann cell that wraps around an axon. Made up of lipoproteins that act as insulators in speeding up the transmission of nerve impulses. 

Neuroglia include (1) ependymal cells lining the ventricles of the brain and the central canal of the spinal cord, (2) cells of the PNS (Schwann cell) and CNS (oligodendrocyte) that wrap around axons to form compacted plasma membranes (myelin) that provide electrical insulation to speed nerve conduction, (3) cells (astrocytes) that interface between nerve cells and capillaries in the CNS, regulate interstitial water content, concentration, remove and metabolize certain NT molecules, and proliferate following injury. 

Anyone who bites a piece of aluminum foil (such as that used for wrapping candies) in such a way that the foil presses against a dental filling will probably experience a momentary sharp pain. In effect, an electrochemical cell has been created in the mouth, with aluminum (P = -1.66 V) as the anode, the filling as the cathode, and saliva as the electrolyte. Contact between the aluminum foil and the filling short-circuits the cell, causing a weak current to flow between the electrodes. This current stimulates the sensitive nerve of the tooth, causing an unpleasant sensation. 

A class of motile systems completely different from and unrelated to the actin-myosin contractile systems is used in cellular structures as diverse as the mitotic spindle, protozoan and sperm flagella, and nerve axons. These systems are constructed from microtubules, very long, tubular structures built from a helical wrapping of the protein tubulin (Figure 8.19). There are two kinds of tubulin subunits, oi and each of molecular weight 55,000. They are present in equimolar quantities in the microtubule, which can be considered a helical array of ot-/i dimers. Alternatively, we can view the microtubule as consisting of 13 rows, or protofilaments, of alternating ot and subunits. Because the oi and b units are asymmetrical proteins, with a defined and reproducible orientation in the fiber, the microtubule has a definite sense of direction. 

Microtubules are systems of very long tubular structures built from a helical wrapping of tubulin (Figure 8.19). Tubulin is involved in motility within cells, such as in the mitotic spindle, flagella, and nerve axons. Tubulin is composed of two subunits, ot and each of molecular weight 55,000. They are present in equimolar amounts in tubulin as dimers. 

The myelin sheath is a lipid-rich material that is wrapped around the axons of nerve cells. Composed largely of sphingomyelins and cerebrosides, the sheath functions so as to... 

A nerve is a continuation of the medullary fubftance of the brain from the head or fpine towards the other parts of the body, wrapped in its proper membrane. 

Myelin is the lipid-rich membrane sheath that surrounds the axons of nerve cells it has a particularly high content of sphingomyelins. It consists of many layers of plasma membrane thathave been wrapped around the nerve cell. 

As can be seen in Figure 16.2, the sensory fibers (afferent neurons) course together in bundles with the motor fibers (efferent neurons) from the periphery to the spinal cord (2). The cell bodies of the sensory fibers are found at the point at which the nerve enters the vertebra, and they are seen as enlargements on the nerve bundles. The cell bodies of the motor fibers are found within the spinal cord. The bundles of sensory and motor fibers outside the spinal cord are wrapped in a connective tissue sheath, the epineurium. Groups of fibers are found within this nerve" in small bundles, each of which is surrounded by connective tissue known as perineurium and, in even smaller tubes of connective tissue, called endoneurium. 

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