Axoplasm

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Axoplasm is the cytoplasm within the axon of a neuron. Neural processes (axons and dendrites) contain about 99.6% of the cell’s cytoplasm, and 99.7% of that is in the axons (Sabry et al., 1995).

Axoplasm has a different composition of organelles and other materials than that found in the neuron's cell body or dendrites. For example, axons lack ribosomes and thus rely on axoplasmic transport to bring proteins to areas where they are needed. In axoplasmic transport, materials are carried through the axoplasm to or from the soma.

The electrical resistance of the axoplasm, called axoplasmic resistance, is one aspect of a neuron's cable properties, because it affects the rate of travel of an action potential down an axon. If the axoplasm contains many molecules that are not electrically conductive, it will slow the travel of the potential because it will cause more ions to flow across the axolemma (the axon's membrane) than through the axoplasm.

[edit] Reference

• Sabry J., O’Connor T. P., and Kirschner M. W. (1995). Axonal Transport of Tubulin in Ti1 Pioneer Neurons in Situ. Neuron. 14: 1247-1256.

Nervous tissue - edit

Neurons (gray matter): soma, axon (axon hillock, axoplasm, axolemma, neurofibril/neurofilament), dendrite (Nissl body, dendritic spine) types (bipolar, pseudounipolar, multipolar, pyramidal, Purkinje, Renshaw, granule) Synapses: neuropil, boutons, synaptic vesicle, neuromuscular junction, electrical synapse Sensory receptors: Free nerve ending, Meissner's corpuscle, Merkel nerve ending, Muscle spindle, Pacinian corpuscle, Ruffini ending, Olfactory receptor neuron, Photoreceptor, Hair cell, Taste bud Glial cells: astrocyte, ependymal cells, microglia, radial glia Myelination (white matter): Schwann cell, oligodendrocyte, nodes of Ranvier, internode, Schmidt-Lanterman incisures, neurolemma closely related Connective tissue: epineurium, perineurium, endoneurium, nerve fascicle, meninges