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Understanding Central Nervous System Functions

Mar 31, 2025

Lecture Notes: Central Nervous System (CNS) Part Two

Overview

  • Continued discussion on the central nervous system
  • Focus on higher order brain functions and spinal cord
  • Topics include: Limbic system, reticular formation, memory, language, EEGs, sleep, meninges, CSF, blood-brain barrier, spinal cord anatomy

Brain Functional Networks

Limbic System

  • Emotional Brain
    • Structures: Cingulate gyrus, amygdaloid body, hippocampus
    • Functions: Emotion recognition, memory, emotional expression
  • Regions involved:
    • Cerebrum: Cingulate gyrus, amygdaloid body, hippocampus
    • Diencephalon: Hypothalamus (controls autonomic functions, emotions)
    • Associated with the hypothalamus and pituitary gland

Reticular Formation

  • Reticular Activating System (RAS)
    • Important for consciousness, alertness
    • Located in the brainstem (midbrain, pons, medulla oblongata)
    • Functions: Filtering sensory input, maintaining wakefulness
    • Sleep: RAS inhibited during sleep and by alcohol/drugs
    • Damage can lead to coma
    • Controls cardiovascular, respiratory functions

Higher Order Functions

Language

  • Broca's Area
    • Located in frontal lobe
    • Responsible for speech production
  • Wernicke's Area
    • Located in temporal/parietal lobe
    • Important for language comprehension
  • Cerebral Dominance
    • Typically left hemisphere dominant
    • Left: Language, math
    • Right: Artistic abilities, body language

Memory

  • Key Regions
    • Hippocampus and temporal lobes
    • Types: Short-term (temporary), Long-term (consolidation)
  • Amnesia
    • Anterograde: Can't form new memories
    • Retrograde: Loss of past memories

Brain Waves & EEGs

  • Types of Brain Waves
    • Alpha: Relaxed, awake
    • Beta: Alert, awake
    • Theta: Children, early sleep
    • Delta: Deep sleep
  • Consciousness
    • Syncope: Fainting
    • Coma: Prolonged unconsciousness

Sleep

  • REM and NREM Sleep Cycles
    • REM: Dreaming, muscle inhibition
    • NREM: Stages 1-4, with 3 and 4 as deep sleep
    • Controlled by hypothalamus and RAS

Brain Protection

Meninges

  • Layers: Dura mater, arachnoid mater, pia mater
  • Spaces: Epidural, subdural, subarachnoid (contains CSF)

Cerebrospinal Fluid (CSF)

  • Produced in ventricles, circulates in subarachnoid space
  • Functions: Cushioning, nutrient delivery

Blood-Brain Barrier (BBB)

  • Tight junctions between endothelial cells
  • Selective: Allows nutrients, blocks toxins
  • Absent in areas needing hormone release (e.g., pituitary gland)

Spinal Cord

Anatomy

  • Ends around L1/L2 vertebrae
  • Surrounded by vertebrae and meninges
  • Spinal Nerves: 31 pairs, mixed (sensory and motor)

Cross-Section

  • Gray Matter
    • Dorsal Horn: Sensory inputs
    • Lateral Horn: Autonomic outputs
    • Ventral Horn: Somatic outputs
  • White Matter
    • Ascending tracts: Sensory
    • Descending tracts: Motor

Disorders

  • TBI: Concussion, contusion
  • Spinal Cord Injury: Paraplegia, quadriplegia
  • Diseases: Polio, ALS

Pathways

  • Ascending: First, second, third-order neurons
  • Descending: Upper and lower motor neurons
  • Key Pathways: Dorsal column, spinothalamic, spinocerebellar

Conclusion

  • Explored complex brain functions
  • Detailed anatomy and function of spinal cord
  • Discussed neural pathways and disorders

Study Tip: Focus on understanding the functional roles of different brain regions and the spinal cord in relation to both sensory input and motor output. Review the structure and significance of the meninges and CSF in protecting the CNS.

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