Divisions of the Nervous System

Major Divisions

1. Central Nervous System (CNS)

   • Composed of the brain and spinal cord.

2. Peripheral Nervous System (PNS)

   • Consists of nerves running throughout the body.
   • Subdivided into:
     • Somatic Nervous System
       • Carries sensory signals from the body to the CNS.
       • Carries motor signals from the CNS to skeletal muscles.
       • Associated with voluntary movements (e.g., clicking a video).
     • Autonomic Nervous System
       • Sometimes called the involuntary nervous system.
       • Regulates the internal environment of the body.
       • Carries signals between internal organs and the CNS.
       • Involved in processes like digestion and heartbeat.

Autonomic Nervous System Subdivisions

1. Sympathetic Nervous System

   • Stimulates and mobilizes energy resources.
   • Involved in fight or flight responses.
   • Effects include increased heart rate, blood pressure, and sweat gland stimulation.

2. Parasympathetic Nervous System

   • Conserves energy.
   • Involved in rest and digest responses.
   • Effects include stimulating digestion, increasing salivation, and slowing heart rate.

These divisions play crucial roles in both voluntary and involuntary bodily functions, and are integral to the body's ability to respond to various internal and external stimuli.