Most closely identified with the brain and the spinal cord, the central nervous system is the system in the body that collects all information from and coordinates the activity of the body.

The brain responsible for coordinating body function, integrating sensory information, and regulate the homeostasis of the body. It is divided into two hemispheres that communicate with one another through a bundle of nerve fibers called the corpus callosum, and a smaller bundle called the anterior commissure. The brain consists of billions of nerve cells and trillions of glia that are housed in different areas of the brain, separately known as the cerebral cortex, cerebellum, brain stem, hypothalamus, thalamus, hippocampus, midbrain, and basal ganglia. The tissues that make up the brain is known as gray matter of white matter. Each area of the brain is responsible for a specific set of functions. 

The spinal cord is responsible for transmitting signals from the brain to the rest of the body. 

In humans, the brain is protected by the skull and the spinal cord is protected by the vertebrae. They are both encased in cerebrospinal fluid that works to create a special environment for nervous tissue and a buffer against physical damage.