As it turns out, nerves are a bit more complicated than you might think. For one thing, they can be both sensory and motor. This means that they carry messages in both directions: to the brain and from the brain. In addition, these nerve cells—or neurons—are involved with practically every bodily function imaginable. And then there’s that whole issue of touch…
But while nerves have all these different functions, they also rely on a few key structures for their very existence. First off, the synapse is an area at which a neuron releases chemicals called neurotransmitters. Upon contact with a receptor on another neuron, these neurotransmitters allow neurons to communicate. The axon terminal is where the neurotransmitters are stored and waiting for release by the axon—a part of the neuron that carries electrical impulses away from the cell body. Finally, dendrites are small fibrous protrusions that send information back to the cell body.
Here’s another look at how it all works: scientists believe that there are around 10 to 100 billion neurons in each of our brains-with about one trillion connections between them. They also make up about 60% of the gray matter in our skulls, with the rest made up of supporting cells called glial cells. Those glia can indeed support neurons by providing them with oxygen and nutrients, as well as remove waste products and cellular debris.
So why do we need so many neurons? Well, first off, they’re all different. Each is specialized to carry out a different function—some are sensory while others help us move or even process pain (ouch!). The more we learn about these cells, the more complex their role in bodily function becomes.
So what happens when something goes wrong with your nerves? Well, that depends on what part of your nervous system is affected. For example, peripheral nerves are those that run through your limbs to organs like your muscles and skin. In fact, there are around 1 million of them in the human body! They can be affected by several kinds of diseases. One example is polyneuropathy, or nerve degeneration. This condition can cause you to lose feeling in a particular limb or your entire body—and it can also cause problems like pins-and-needles sensations (also called paresthesia). Ehlers-Danlos syndrome type IV (EDS IV) is another kind of disease that affects peripheral nerves, as well as internal organs like the heart and stomach.
