Nerve cell fibers

MS is an inflammatory demyelinating autoimmune disease affecting the CNS. In MS, the immune system attacks the myelin sheath of nerve cell fibers in the brain and spinal cord. MS is predominantly a T-lymphocyte mediated disorder, and cytokines may therefore have a key role in the pathogenesis of the disease. MS is the only neurological disorder where therapeutic manipulation of the cytokine system influences development of the disease (Adibhatla and Hatcher,... 

Nerven-, nerve, neuro-. -entzundung,/. neuri. tis. -faser,/. nerve fiber, -gewebe, n. nerve tissue, -kitt, m. (Anat.) neuroglia, -kunde, -lehre, /. neurology, -masse, /. = Nerven-stoff, -reiz, m. nervous stimulus, -stoff, m. nerve substance, neural substance, -system, -werk, n. nervous system, -zelle, /. nerve cell. 

Neuroanatomists have taken advantage of the phenomenon of fast retrograde transport to locate remote nerve cell bodies in the CNS of an experimental animal that are connected to an identified axonal fiber tract whose origin is uncertain. The tracer material [purified horseradish peroxidase (HRP) enzyme] is injected in the region of the axon terminals, where it is taken up by endocytosis and then is carried by retrograde axonal transport over a period of several hours to days back to the nerve cell body. The animal is sacrificed, and the enzyme tracer is localized by staining thin sections of the brain for peroxidase activity. 

Hydroxy tryptamine, or serotonin, is a neurotransmitter in the central nervous system (CNS). The nerve-cell bodies of the major serotoninergic neurones are in the midline raphe nuclei of the rostral pons, and ascending fibers innervate the basal ganglia, hypothalamus, thalamus, hippocampus, limbic forebrain, and areas of the cerebral cortex. The serotoninergic system plays an important role in the control of mood and behavior, motor activity, hunger, thermoregulation, sleep, certain hallucinatory states, and some neuro-endocrine mechanisms. 

The gray matter is composed of nerve cell bodies and unmyelinated intemeuron fibers. The location of the gray matter in the spinal cord is opposite to that of the brain. In the brain, the gray matter of the cerebrum and the cerebellum is found externally forming a cortex, or covering, over the internally located white matter. In the spinal cord, the gray matter is found internally and is surrounded by the white matter. 

Cholinergic Relating to nerve cells or fibers that employ acetylcholine as their neurotransmitter. 

Central Nervous System (CNS). The human nervous system is an integrated communication network that sends and receives information throughout the body. This network is divided into two main divisions central nervous system (CNS) and peripheral nervous system (PNS). The CNS is the command center of this network and is made up of the brain and spinal cord. The PNS is the interface of the nervous system with the rest of the body and the external environment. It is comprised of nerve fibers and small clusters of nerve cells known as ganglia. 

Under normal circumstances, neurons (nerve cells in the brain) carry electrical signals along wire-like nerve fibers... 

Many cells are far from spherical for example, human red blood cells are discs 8 x 8 x 1 to 2 pm with a volume of 80 pm3. Plant fiber cells may be several millimeters in length. Nerve cells of animals have long extensions, the axons, which in the human sometimes... 

In all sensory systems, this afferent pathway consists of at least three neurons (nerve cell and nerve fiber) arranged in a continuous chain. The transfer of nervous signals from one neuron to the next occurs in well-defined loci called synapses. 

Volatile solvents are useful in industry and in homes because of their ability to dissolve fat. When inhaled, however, this property poses problems to the brain and the network of nerves that connect the brain and spinal cord to the rest of the body, ...thus, because the brain is a lipid-rich organ, chronic solvent abuse dissolves brain cells, the American Academy of Pediatrics wrote in a 1996 policy paper about inhalants. The chemical vapors also damage the myelin sheath, the fatty wrapper that insulates the fibers of many nerve cells that carry signals. 

Cell studies on scaffolds of nano- and submicrometer-scaled fibers have shown that these dimensions promote not only cell adhesion, but also have beneficial effects on proliferation and differentiation of cells [174-177], These effects are more prominent with decreasing fiber diameters. It seems relevant that the cells can be guided and bridged by the artificial fibers. Meshes with aligned fibers are particularly promising, e.g., for guiding the growth of nerve cells (Fig. 8) [178],... 

Fig. 8 Nerve cells adjust their adhesion and migration to the corresponding structure, as seen here on random (a, c) and aligned (b, d) cells, (a, b) SEM pictures of PCL nanofibers where gioma cells adhered and followed the fiber alignment (see asterisk in b). (c, d) Motion cell-tracking 20 individual trajectories were traced manually after a total tracking period of 36 h. Scale bars (a, b) 10 pm. Reprinted, with permission, from [178] copyright (2009) Mary Ann Liebert...

Fiber electrodes -> microelectrodes in a form of bare fibers as the conductive elements, protruding from the end of an insulator, usually made of carbon fibers of 7-8 pm diameter and sealed in glass capillaries often used for direct measurements (e.g., using fast cyclic voltammetry) of the in-vivo release of oxidiz-able neurotransmitters, such as dopamine, serotonin, norepinephrine, or epinephrine, from living cells. Also used to monitor electric activity of single nerve cells or for diagnostic purposes in electroanalysis. S ee also carbon fiber electrode. 

Figure 7.2. Stractures of synapses, a Some anatomical variations. Left An intemeural synapse connects two nerve cells. Middle A neuromuscular synapse (also called motor endplate) connects the terminal button of a motoneuron to a skeletal muscle cell. Right An automic nerve cell may form several secretory varicosities that release the transmitter in the target tissue, without forming a circtrmscribed contact zone with an individtral target cell, b Electron microcoscopy of a nemomnsctrlar synapse. The synaptic cleft is very narrow, so that diffusion of secreted transmitter to the receptors on the postsynaptic membrane is fast. Ntrmerous vesicles line up close to the presynaptic membrane. Note the striated myofilament in the postsynaptic cell, c Light microscopy. A single nemon branches out and sends terminal buttorrs to multiple muscle fibers.

The question remains how can interference effects be produced in the brain One can imagine that when nerve impulses arrive at synapses (the junction between two nerve cells), they produce electrical events on the other side of the synapse that take the form of momentary standing wave fronts. Typically the junctions made by a nerve fiber number in the dozens, if not hundreds. 

What kind of neural mechanism plays the role of the coherent light source to make and display holograms Perhaps a kind of coherence results from the anatomical fact that the retina and visual cortex are linked by many thousands of fibers arranged in parallel pathways. Or it could be that the nerve cells in the visual charmel achieve coherence by rhythmic firing. Still another possibility is that coherence results from the operation of the variety... 

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