Brain
The brain's primary role is to function as the body's control
center. This organ receives and interprets nerve signals
from every part of the body and initiates the appropriate
response. These responses include adjustments in internal
bodily functions (eg, heart rate and temperature),
movement, speech, and emotions and consciousness.
• Spinal cord
The spinal cord is a cylinder of nerve tissue that runs down
the center canal in the spine. The nerve fibers in the spinal
cord transmit sensory information toward the brain and
motor signals to the appropriate parts of the body. The
spinal cord also handles some automatic motor
responses to sensory information by itself.