Lecture Notes: Basic Functioning of the Nervous System

Introduction

• The brain is a complex organ involved in a variety of functions like emotions and decision-making.
• The nervous system's basic function involves:
  • Sensory information (afferent) going to the brain/spinal cord.
  • Integration of information in the CNS (Central Nervous System).
  • Motor output (efferent) from CNS to effector organs (muscles, glands).

Components of the Nervous System

Central Nervous System (CNS)

• Brain and Spinal Cord: Integrate and control body functions.
• Endocrine System: Modifies ongoing functions (growth, metabolism).
• Nervous System: Controls fast-reacting functions (heart rate, breathing).

Peripheral Nervous System (PNS)

• Composed of nerves (bundles of axons) extending from the CNS.
• Spinal Nerves: Emerge from the spinal cord, innervate body parts.
• Cranial Nerves: Emerge from the brain, innervate head regions.

Nervous System Functional Divisions

Sensory Division

• Somatic Sensory Fibers: Convey information from skin, muscles, bones.
• Visceral Sensory Fibers: Convey information from organs.

Motor Division

• Somatic Nervous System: Controls voluntary muscle movements.
• Autonomic Nervous System: Controls involuntary functions (heart rate, digestion).
  • Sympathetic Division: "Fight or flight" response.
  • Parasympathetic Division: "Rest and digest" response.

Brain Protection and Development

• Skull and Meninges: Protect the brain; layers include dura mater, arachnoid mater, pia mater.
• Cerebrospinal Fluid (CSF): Cushions the brain against impact.
• Brain Development: Neural plate forms the central nervous system.

Brain Structure and Function

Brainstem

• Controls fundamental processes (breathing, heart rate).

Diencephalon

• Involved in emotional responses and unconscious processing.

Cerebrum

• Seat of consciousness; responsible for higher cognitive functions.
• Gray Matter: Decision-making, impulse initiation.
• White Matter: Pathways for neural impulses.

Hemispheres and Lobes

• Frontal Lobe: Motor commands, problem-solving, speech (Broca's area).
• Parietal Lobe: Sensory processing, language understanding (Wernicke's area).
• Temporal Lobe: Auditory processing.
• Occipital Lobe: Visual processing.
• Insula: Balance, self-awareness, linked to emotions.
• Gustatory Cortex: Taste processing.

Integration and Coordination

• Corpus Callosum: Connects the two hemispheres.
• Association Fibers: Connect areas within the same hemisphere.
• Commissural Fibers: Connect corresponding areas in opposite hemispheres.
• Projection Fibers: Connect the brain with the spinal cord.

Conclusion

• Understanding the nervous system involves recognizing the roles of different structures and how they coordinate to control body functions. The brain's complexity and adaptability (neuroplasticity) allow for dynamic responses to environmental changes.