Nervous System Overview

The Nervous System

  • The right half of the brain controls the left half of the body.

Central Nervous System

  • Comprises the brain and spinal cord.
  • Acts as the body’s control center, coordinating activities via neuronal impulses.
  • Depicted in yellow in diagrams.

Peripheral Nervous System

  • Composed of nerves that transmit messages to/from the central nervous system.
  • Functions like telephone wires connecting homes.
  • Illustrated in green in diagrams.

Components of Peripheral Nervous System

  • Somatic Nervous System:
    • Relays information between skin, skeletal muscles, and central nervous system.
    • Consciously controlled, except for reflexes.
  • Autonomic Nervous System:
    • Controls involuntary actions from CNS to organs.
    • Subdivided into:
    • Sympathetic Nervous System: Activates in stress (fight or flight).
    • Parasympathetic Nervous System: Functions during rest.

Brain Structure

  • Divided into:
    • Cerebrum: Higher mental functions; covered with cerebral cortex.
    • Diencephalon: Includes structures like thalamus and hypothalamus.
    • Cerebellum: Coordinates muscle movements.
    • Brainstem: Composed of medulla oblongata, pons, midbrain; controls involuntary actions.

Cerebrum

  • Responsible for conscious activities, intelligence, memory, language, muscles.
  • Features sulci (shallow grooves) and gyri (elevated ridges).

Cerebellum

  • Develops muscle coordination and physical skill memory.
  • Injuries result in jerky movements.

Brainstem

  • Controls involuntary activities; resembles the brain of reptiles.

Locked-In Syndrome

  • Damage to motor tracts; individuals are aware but cannot move.

Brain Protection

  • Cranial Meninges: Three layers protect the brain.
  • Cerebrospinal Fluid (CSF): Cushions the brain, maintains temperature, removes wastes.
  • Blood-Brain Barrier: Limits harmful substances from entering brain.

Ventricles and Cerebrospinal Fluid

  • Four linked cavities filled with CSF, providing buoyancy and waste removal.

Blood-Brain Barrier

  • Composed of endothelial cells with tight junctions; selectively allows substances to pass.

Infectious Meningitis

  • Inflammation of meninges; symptoms include headache, fever, and stiff neck; can be viral (mild) or bacterial (severe).