Divisions of the Nervous System

Major Divisions

• Central Nervous System (CNS)
  • Comprised of the brain and spinal cord.
• Peripheral Nervous System (PNS)
  • Consists of nerves running throughout the body.

Subdivisions of the Peripheral Nervous System

• Somatic Nervous System

  • Carries sensory signals from the body to the CNS.
  • Carries motor signals from the CNS to skeletal muscles.
  • Associated with voluntary movement.
  • Example: Clicking a video involves a signal from the brain to the finger.

• Autonomic Nervous System (ANS)

  • Sometimes called the involuntary nervous system.
  • Regulates the internal environment of the body.
  • Carries signals between internal organs and the CNS.
  • Involved in regulating functions like digestion and heartbeat.

Subdivisions of the Autonomic Nervous System

• Sympathetic Nervous System

  • Stimulates and mobilizes energy resources.
  • Involved in fight or flight responses.
  • Example: Increases heart rate, blood pressure, and stimulates sweat glands during frightening situations.

• Parasympathetic Nervous System

  • Conserves energy.
  • Involved in rest and digest responses.
  • Example: Stimulates digestion, increases salivation, and slows heart rate during meal times.

Summary

• CNS: Brain and spinal cord.
• PNS: Nerves throughout the body, with somatic (voluntary) and autonomic (involuntary) subdivisions.
• ANS: Further divided into sympathetic (fight or flight) and parasympathetic (rest and digest) systems.