Major Organs and Divisions of the Nervous System
Organization of the Somatic Nervous System
- In nerves, somatic nervous system (Gr. soma; body) axons carry signals that allow the central nervous system (CNS) to voluntarily or consciously monitor the external environment and regulate the body’s responses activities.
- The process begins when somatic receptors detect changes in the external (surrounding) environmental.
- Somatic receptors are modified nerve cell endings located in the skeletal muscles, joints, and sense organs (eyes, ears, mouth, and nose).
- When stimulated, the somatic receptors generate electrochemical impulses or action potentials in the axons of somatic sensory neurons (afferent neurons).
- Each axon runs the length of a nerve and conducts signals directly into the CNS.
- Somatic neurons supply the CNS with vital input information and their axons are typical enveloped by a series of Schwann cells. The rate of impulse conduction is increased by the structure and arrangement of these support cells.
- In the CNS, neurons called interneurons image, interpret, and integrate the input delivered by the sensory neurons (except for reflexes). Response activities are then planned and relayed to somatic motor neurons.
- The motor neurons (efferent neurons) conduct impulses out to the skeletal muscles (effectors), which produce required response movements. Somatic motor neurons are also covered by a series of Schwann cells because the muscle actions need to be coordinated and rapid.