Nerve

From ArticleWorld

Nerves are a cable-like packs of axons, including the glia that ensheath the axons in myelin. The nerves are a part of the Peripheral Nervous System, handling the transportation of signals between the Central Nervous System and muscles, sensors etc.

Types of nerves

Depending on how they perform this transportation, nerves can be afferent and efferent.

• Afferent nerves conduct signals from the sensors (like eyes or tactile sensors) to the Central Nervous System.
• Efferent nerves, on the other hand, conduct signals from the Central Nervous System to the various executors like muscles or glands. The signals they conduct are called action potentials. These action potentials are electrical waves that begin in the neuron body and propagate to the end of the axon. Due to their electrical nature, they can propagate very quickly. Propagation through series of neurons is done through very quick chemical reactions occuring at the interneural joints (synapses).

These two types of fibres are often arranged together, forming what a type of formations known as mixed nerves.

Nerve injury

Damage to nerves can be determined by various factors, like physical injuries, swelling or diseases like diabetes or the Guillain-Barre syndrome. Swelling or injury that place pressure on a nerve determine pinched nerves, which are usually accompanied by physical pain. Severe nerve damage can lead to sensations of numbness and weakness, but also to more severe situations like paralysis.

Sometimes, patients can experience what is known as referred pain, a sensation of pain that does not occur at the actual site of damage. This happens because the nerve signals pain from all the parts of the area it is responsible for, not just the damaged one.