Subdivisions of the Nervous System

The CNS, comprising the brain and spinal cord, acts as the primary integration center for sensory and motor information. It is anatomically divided into gray matter, which contains neuron cell bodies, and white matter, which consists of myelinated axons responsible for signal transmission.

The PNS connects the CNS to the rest of the body. It is divided into the somatic nervous system, which controls voluntary skeletal muscle movements, and the autonomic nervous system (ANS), which regulates involuntary functions like digestion and heart rate.

The ANS is split into the sympathetic nervous system, managing 'fight-or-flight' responses, and the parasympathetic nervous system, managing 'rest-and-digest' functions. Additionally, the enteric nervous system independently manages the gastrointestinal tract, acting as a specialized subsystem.