How Nerves Work

The Simple Version of How Nerves Work

Knowing How Your Nerves Work Makes It Easier to Understand Peripheral Neuropathy

The peripheral nervous system is complicated, but the way it works is pretty straightforward. We’ll break down how nerves work, so you can better understand what’s happening when peripheral neuropathy takes its toll.

Nerves can be rather complicated…but when it comes to the way they work, they’re refreshingly straightforward. Your nervous system is essentially in charge of everything the human body does and experiences.

Bump your foot against the door jamb, and it’s your sensory nerves that communicate the feeling up to your brain. Similarly, cold air against bare skin (or any other change in temperature) is going to be relayed to your brain by sensory nerves.

Your motor nerves do the work of enabling you to move your limbs, helping your muscles contract to lift your arm when you’ve decided it’s time to do so.

Finally, the autonomic nerves are in charge of regulating the different automatic things your body does, without your conscious thought — breathing, heart rate, and so forth.

So how do they accomplish this?

The Action Potential

To put it very simply: Your nerves work by sending signals throughout your body. The process goes both ways, but it always starts and ends with the central nervous system (which is located in your brain and your spine).

Your central nervous system uses the peripheral nervous system to either send or receive signals throughout the body. This means that your central nervous system sends a signal out when it wants to make something happen…or that it receives an incoming signal when your body needs to process some type of information or stimulus.

Before these signals reach their destination, they’re called action potential. The action potential is a pretty nifty thing, as it gets changed from a chemical signal to an electrical one, and then back again.

From Axon to Synapse to Axon Again

Once your body sends out a signal, it originates as an action potential, an electrical signal produced by the central nerve body. This signal then gets sent from the central body along the axon that extends out from the nerve. The axons, you’ll recall, travel from the brain or spine all the way out to the part of the body that a particular nerve is in charge of.

Sometimes, the signal’s destination is so far away that multiple axons have to be used in order for it to get to where it’s going. In either case — whether going from one axon to the next or actually reaching its final destination — the action potential must cross a synapse.

These are little spaces between your nerve endings that the signal jumps across. As it reaches the synapse, the action potential causes the release of something called a neurotransmitter, which is a chemical messenger that aids in the sending of nerve impulses.

As the neurotransmitter crosses the synapse, it binds with receptors on the other side. These receptors then turn this chemical compound back into an electrical signal, which then continues down the axon. This process basically repeats itself until the action potential has made its way all the way to its eventual destination.

Peripheral Neuropathy: The Great Signal Blocker

Peripheral neuropathy, understandably enough, mostly does its damage by interrupting the normal function of your peripheral nervous system. This means that, in one way or another, your nerve fibers aren’t being allowed to do their jobs the way they normally would be.

This can happen in a variety of different ways, and depending on the specific type of damage being inflicted on your nervous system, different symptoms will present themselves.

Certain kinds of peripheral neuropathy are said to be demyelinating. This means that they actually cause nerve damage by eating away at the myelin sheath surrounding your thicker nerve fibers, slowing down their conductivity and making them vulnerable to further damage.

If the myelin sheath gets completely taken out, the neuropathy becomes axonal, which is more serious. Axonal neuropathy directly impairs the way your nerve endings work.

When motor nerves become damaged, your movement tends to be impaired. This might start with something like slight unsteadiness, but can eventually turn into full-blown balance problems. Trouble with activities like going up stairs or picking up small objects can also be an early indicator.

Sensory nerves respond to damage in one of two different ways. Positive symptoms mean that your sensory nerves are overacting, and will send signals that aren’t appropriate. This can mean overreacting to normal stimulation, or it can mean reacting to input that isn’t even there, to begin with. Negative symptoms mean that your nerves are either not sending enough information, or aren’t sending any at all. This can result in loss of sensation or even complete numbness in parts of the body.

Your autonomic nerves respond in a much more dangerous way to damage, as this causes disruption of involuntary body functions that can have serious consequences. Problems with gastrointestinal motility can lead to secondary digestive issues. Improper blood flow can cause a stroke. Autonomic neuropathy is more serious, but it’s also much more rare than sensory and motor nerve damage.

Neurons use axons to send a signal from one part of the body to another. Damage to neurons blocks this signal, leading to neuropathic symptoms.