Oligodendrocytes in the central nervous system (unlike the Schwann cells in the peripheral nervous system) form segments of myelin sheaths of numerous neurons at once.
Table of Contents
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 effect is 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 off the Central nervous system (CNS) to the peripheral nervous system. (The peripheral nervous system is the nervous system outside the CNS.) These are the efferent neurons that carry signals away from the CNS to the peripheral system.
These efferent fibers are divided into the somatic nervous system and the autonomic nervous system. The somatic fibers are responsible for the voluntary movement of our body, i.e. movement that you consciously thought about doing.
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 tutorial, Types and Causes of Brain Damage.
Nutrients in the soil are essential to the proper growth of a land plant. This tutorial deals with the properties of soi..
Bryophytes (nonvascular plants) are a plant group characterized by lacking vascular tissues. They include the mosses, th..
Plants in lentic habitats have features not found in terrestrial plants. They acquired these features as they adapt to t..
Meet the colorful takahē, an extremely rare flightless bird. Find out more about its unique features and why they matte..
With regard to the population size of a species and what factors may affect them, two factors have been defined. They ar..