Motor Neurons

Motor Neuron - isn't that some kind of car?

Our bodies have at least 40 billion neurons, without them we could not live.

A neuron (otherwise known as a nerve cell) is the most basic unit of the nervous system. These amazing cells are able to transport electrical impulses between themselves throughout our entire bodies. Although messages are carried through electrical impulses along the cells, the cells do not touch each other, so the messages are passed to the next nerve cell via a chain of chemical reactions.

When these cells are activated, the speed of these impulses can reach up to 435 kilometers an hour. These nerve cells are all coordinated and are classified into three different categories which include; the left and right hemisphere of the brain, the spinal cord and the peripheral nerves and muscles (peripheral meaning the limbs and torso of our bodies).

What are they made of?

A neuron is an individual cell consisting of a central cell body with many small fibres called dendrites branching out from it in all directions. Attached to it is another longer fibre called an axon, which carries the nerve impulses along so that it can reach the next neuron. The axon is protected by an insulated covering called a myelin sheath, which protects the nerve impulse, so that there is no interference in the message. Some of the axons have diameters as small as a spider web, others are larger and can be wider than 1mm. Depending on what sort of nerve cell it is and where it is situated they can be as long as 1 meter or so short they cannot be seen.

How do they work?

Basically the brain is the coordinator of the body, and the spinal cord acts as a carrier to deliver the messages. The highest levels of messages sent to the body, are as high up as the brain stem (which connects the brain to the spinal cord).

There are two major types of peripheral nerves:

1/ The sensory motor somatic nerve system. It is the sensory nerves that detect things such as heat and pain. These nerves are basically what we use to feel our way through life. The motor nerves are what gives us the capacity to move our way out of danger, and give us the ability of movement through our brain's command.

2/ The autonomic system. This consists of the sympathetic and parasympathetic subdivisions. This system is just as vital as the sensory and motor neurons. It functions on an unconscious level while we are awake and while we sleep. It regulates our heart rate, blood pressure, temperature, nutrient supply, oxygen levels, and regulates the function of our internal organs. The sympathetic and parasympathetic nervous system in basic terms effects how fast or how slow things in our bodies run. It is much more complex than this, functioning in a delicate balance. Generally these systems control the same organs in the body but cause opposite effects.

The sympathetic nerves are what are commonly referred to as the 'fight or flight' nerves. For example, if you see something dangerous and need to get away from it (such as a snake) it is this system that will trigger the release of adrenaline, so that you have the energy to run.

The parasympathetic system does the opposite, once you are out of trouble it will help to calm you down. If you remember ever getting a fright from something, after the danger passed you may remember you felt quite tired.

These two systems work in unison to control bodily functions and in most cases you have no control over them (unless you are using a pain management technique call biofeedback).

The peripheral nervous system is an incredible network of neurons that gives us the ability to function in life, some of which we have control over, some of which we have no idea what is happening. In both cases we should not take for granted what amazing individuals we are, and how we work with such harmonious beauty.

- Louise Ganey (RN)