Lecture on Divisions of the Nervous System

Overview

• The nervous system is a complex, interconnected network.
• Studying this system by breaking it into parts helps us understand its functioning.

Divisions of the Nervous System

Conceptual Framework

1. Information In (Receptors)

   • Special Senses: Seeing, hearing, tasting, touching, and feeling.
   • Visceral Receptors: Monitor internal functions (e.g., blood pressure, stomach stretch).

2. Processing (Central Nervous System - CNS)

   • Comprised of the brain and spinal cord.
   • Processes sensory inputs and makes decisions.
   • Decisions can be conscious or subconscious.

3. Response (Effectors)

   • Response organs that produce changes based on CNS decisions.
   • Includes all organs that can react to neural signals.

Peripheral Nervous System (PNS)

• Components: Nerves connecting the brain and spinal cord to the body.
• Divisions:
  • Sensory Division (Afferent): Carries information to the CNS.
  • Motor Division (Efferent): Carries information from the CNS to effectors.

Central Nervous System (CNS)

• Main hub for integrating sensory inputs and directing responses.

Motor Division Breakdown

Somatic Division

• Controls voluntary actions (e.g., skeletal muscle movements).
• Voluntary decisions like running, dancing, etc.

Autonomic Division

• Controls involuntary actions (e.g., heart rate regulation).
• Subdivided into:
  • Sympathetic Division:
    • Stress response ("fight or flight").
    • Increases heart rate, dilates pupils, increases alertness, induces sweating.
  • Parasympathetic Division:
    • Relaxation response ("rest and digest").
    • Slows heart rate, constricts pupils, facilitates digestion.

Sympathetic vs. Parasympathetic

• Sympathetic: Activated during stress, increases alertness, prepares body for action.
• Parasympathetic: Activated during rest, promotes digestion, reduces stress effects.

Key Takeaways

• Understanding the divisions helps in grasping how the nervous system operates.
• Sympathetic and parasympathetic systems balance stress and relaxation responses.
• The nervous system is one interconnected unit, but division aids in comprehension.