Why is the White matter white?
The central nervous system is primarily composed of the brain and the spinal cord. These two organs’ main function is to send and receive impulses via the spinal cord to and from the brain. The brain comprises neurons which are the elemental cells that are essential in transmitting impulses. The main composites of the brain and the spinal cord are the white matter and the gray matter. These two function in conjunction with one another in order for the brain and the rest of the central nervous system to function properly. The gray matter is the one responsible for the processing of impulses. The white matter, on the other hand, is the one responsible for the passage of impulses, either towards or away from the brain, between the left and the right hemispheres or between the lobes contained in similar hemispheres.
White matter is composed of electrically insulating material that is found commonly in the deeper parts of the brain and in the superficial areas of the spinal cord. It is named white matter primarily because its color is white. The reason behind its color is that white matter is composed myelin and veined capillaries. Seventy to eighty-five percent of myelin is mostly composed of lipids while the remaining fifty to thirty percent are proteins. It is because of its lipid component that gives off a white color when exposed. This white-colored myelin functions as an insulator that allows transmission of nerve signals to relayed at a faster pace.
Aside from its function of transmitting information, white matter controls the unconscious functions of the body such as the regulation of vital signs as well as thirst and hunger control, release of hormones and controlling the limbic system, which are all contained in the brain.