1. Explain both the anatomical and functional divisions of the nervous system. Include the subdivisions of each.
The nervous system is divided into two main components: the central nervous system (CNS) and the peripheral nervous system (PNS) (Walker, 2002, 77). The central nervous system consists of the brain and spinal cord, and functions as the command center for the nervous system. The CNS coordinates the activities of the entire body. It receives and analyzes information through the PNS from the sense organs and other receptors throughout the body, and sends out response information to muscles and glands based on past experience. The peripheral nervous system is composed of the nerves that extend from the brain and spinal cord, which function to relay messages between the CNS and the rest of the body. The PNS has three components, one which relays information to the CNS and two which relay information from the CNS.
The sensory component of the PNS gathers information from the various sensory organs of the body (eyes, ears, nose, pain sensors) and relays this information concerning what is happening in the external environment to the CNS (Walker, 2002, 77). The two components emanating from the CNS are the somatic and autonomic nervous systems. The somatic component relays information from the CNS to body components to make them react in appropriate ways to the messages it has received from the sensory nerves. For example, the somatic component relays information to skeletal muscle to cause contraction, enabling the body to respond to external events under conscious control. The autonomic component of the PNS is not under voluntary control. It relays information to the internal organs of the body, controlling their activities in response to the information it has received from the sensory nerves. For example, it can increase the heart rate when extra oxygen is needed by the tissues, and raises blood glucose le...