Neuroscience

A little myelin goes a long way to restore nervous system function

In the central nervous system of humans and all other mammals, a vital insulating sheath composed of lipids and proteins around nerve fibers helps speed the electrical signals or nerve impulses that direct our bodies to walk, ...

Neuroscience

With the right rehabilitation, paralyzed rats learn to grip again

After a large stroke, motor skills barely improve, even with rehabilitation. An experiment conducted on rats demonstrates that a course of therapy combining the stimulation of nerve fiber growth with drugs and motor training ...

Medical research

New strategy to treat multiple sclerosis shows promise in mice

Scientists at The Scripps Research Institute (TSRI) have identified a set of compounds that may be used to treat multiple sclerosis (MS) in a new way. Unlike existing MS therapies that suppress the immune system, the compounds ...

Overweight & Obesity

The Fat Chip: Controlling obesity the smart way

(Medical Xpress)—Gastric banding, a common surgery to reduce obesity, leaves much to be desired. Typically, the patient is left with a feeling of constant hunger. Stimulators implanted in the feeding centers of the brain, ...

Medical research

Stem cells grow fully functional new teeth

(Medical Xpress) -- Researchers from Japan recently published a paper in PLoS One describing their successful growth and transplantation of new teeth created from the stem cells of mice.

Medical research

Exercise and caloric restriction rejuvenate synapses in lab mice

(PhysOrg.com) -- Harvard University researchers have uncovered a mechanism through which caloric restriction and exercise delay some of the debilitating effects of aging by rejuvenating connections between nerves and the ...

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Axon

An axon or nerve fiber is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma.

An axon is one of two types of protoplasmic protrusions that extrude from the cell body of a neuron, the other type being dendrites. Axons are distinguished from dendrites by several features, including shape (dendrites often taper while axons usually maintain a constant radius), length (dendrites are restricted to a small region around the cell body while axons can be much longer), and function (dendrites usually receive signals while axons usually transmit them). All of these rules have exceptions, however.

Some types of neurons have no axon—these are called amacrine cells, and transmit signals from their dendrites. No neuron ever has more than one axon; however in invertebrates such as insects the axon sometimes consists of several regions that function more or less independently of each other. Most axons branch, in some cases very profusely.

Axons make contact with other cells—usually other neurons but sometimes muscle or gland cells—at junctions called synapses. At a synapse, the membrane of the axon closely adjoins the membrane of the target cell, and special molecular structures serve to transmit electrical or electrochemical signals across the gap. Some synaptic junctions appear partway along an axon as it extends—these are called en passant ("in passing") synapses. Other synapses appear as terminals at the ends of axonal branches. A single axon, with all its branches taken together, can innervate multiple parts of the brain and generate thousands of synaptic terminals.

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