Differentiate between gray matter and white matter.

Gray matter and white matter are two distinct components of the central nervous system, which includes the brain and spinal cord. They are differentiated by their appearance, location, composition, and function.

Appearance and Location:
- Gray matter is so named because it appears grayish in color due to the presence of neuronal cell bodies and a lack of myelin. It is found on the outer layer of the brain, known as the cerebral cortex, and also in regions called nuclei deep within the brain and throughout the spinal cord.
- White matter appears white because it is composed mainly of myelinated axons, which are nerve fibers surrounded by a white, fatty substance called myelin. This myelin sheath helps to insulate the axons and increases the speed of electrical signal transmission. White matter is located beneath the gray matter cortex in the brain and surrounds the gray matter in the spinal cord.

Composition:
- Gray matter is composed primarily of neuronal cell bodies, dendrites, unmyelinated axons, glial cells, and capillaries. The lack of myelin contributes to its gray color.
- White matter consists mostly of myelinated axons and glial cells, particularly oligodendrocytes, which are responsible for the formation of the myelin sheath in the central nervous system.

Function:
- Gray matter is primarily involved in processing and interpreting information. It is where most of the brain's synaptic connections occur, and it plays a crucial role in various brain functions, including muscle control, sensory perception, memory, emotions, speech, decision making, and self-control.
- White matter is responsible for communication between different brain regions and between the brain and spinal cord. The myelinated axons in white matter act as highways for nerve impulses, allowing for rapid transmission of signals across different parts of the nervous system.

In summary, gray matter and white matter are essential components of the nervous system with distinct appearances, locations, compositions, and functions. Gray matter is involved in processing information and is composed of neuronal cell bodies and dendrites, while white matter facilitates communication between different brain regions and is composed of myelinated axons.