Summary of the structural and functional classification of the nervous system

Structural classification: Two subdivisions

1.) Central nervous system and the peripheral nervous system. The central nervous system includes the brain, spinal cord and a complex network of neurons. It acts as the command center for the nervous system.

2.) The peripheral nervous system (PNS) consists of the nerves and neurons that reside or extend outside the central nervous system. Consisting mainly of nerves extending from brain (cranial nerves) and spinal cord (spinal nerves). They carry impulses from sensory receptors to central nervous system and back to necessary glands or muscles.

Functional Classification- concerned only with peripheral nervous system structures & is divided into two subdivisions:

1) Sensory or afferent division- nerve fibers that carry impulses to CNS from sensory receptors. Somatic sensory fibers- delivers impulses from skin, skeletal muscle & joints.

Visceral sensory fibers- delivers impulses from visceral (internal) organs.

2) Motor/efferent division- nerve fibers that carry impulses from central nervous system to effector organs, the muscles and glands, thus bringing about (effecting) a response. Somatic/voluntary nervous system- allows for voluntary control of skeletal muscles, although some activities may be reflexive.

Autonomic/involuntary nervous system- regulates events that are involuntary or automatic, smooth muscle, cardiac muscle & glands. Sympathetic and Parasympathetic bring opposite effects.