Myelin is a substance that forms the myelin sheath associated with nerve cells. This sheath is a layer of phospholipids that increases the conductivity of the electrical messages that are sent through the cell. Diseases such as multiple sclerosis are a result in a lack of this myelin sheath, with the resultant effect being that the conductivity of signals is much slower severely decreasing the effectiveness of the nervous system in sufferers.
In total, there are 43 main nerves that branch of the CNS to the peripheral nervous system (the peripheral system is the nervous system outside the CNS. These are the efferent neurones that carry signals away from the CNS to the peripheral system.
Somatic Nervous System
These efferent fibres are divided into the somatic nervous system and the autonomic nervous system. The somatic fibres are responsible for the voluntary movement of our body, i.e. movement that you consciously thought about doing.
The Autonomic Nervous System
The autonomic nervous system incorporates all the impulses that are done involuntarily, and are usually associated with essential functions such as breathing, heartbeat etc. However this type of system can further be broken down into the sympathetic and parasympathetic systems which keep one another in check in a form of negative feedback such as the release of insulin and glucagon in sugar control of the blood.
All of the actions executed by the autonomic nervous system are unconsciously done.
These informational pulses executed in our nervous system allow us to do our daily functions. The processing of this information is done in the CNS, the brain, a highly developed mass of nerve cells. The inner workings of the brain are investigated on the next page.