The Brain and Spinal Cord

Where does processing of information occur in the nervous system?

The control point of the central nervous system is the brain. Each of the major areas of the brain—the cerebrum, cerebellum, and brain stem—are responsible for processing and relaying information. Like the central processing unit of a computer, information processing is the brain's principal task. Figure 31–8 on the next page provides details about the major areas of the brain.

While most organs in the body function to maintain homeostasis, the brain itself is constantly changed by its interactions with the environment. Sensory experience changes many of the patterns of neuron connections in the brain, and stem cells in the brain produce new neurons throughout life. Many of these new cells originate in regions associated with learning and memory. Far from staying the same, the highly flexible brain reacts to and changes constantly with the world around it.

FIGURE 31–7 The Central Nervous System The central nervous system consists of the brain and spinal cord.

Most of the neurons that enter and leave the brain do so in a large cluster of neurons and other cells known as the spinal cord. The spinal cord is the main communication link between the brain and the rest of the body. The spinal cord is a bit like a major telephone line, carrying thousands of signals at once between the central and peripheral nervous systems. Thirty-one pairs of spinal nerves branch out from the spinal cord, connecting the brain to different parts of the body. Certain kinds of information, including many reflexes, are processed directly in the spinal cord. A reflex is a quick, automatic response to a stimulus. The way in which you pull your hand back quickly when pricked by a pin is an example of a reflex.

In Your Notebook Make a three-column table that lists the major structures of the brain described in Figure 31–8, their functions, and how they interact with at least one other brain structure.