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CNS General Structure

CNS General Structure. Composed of brain and spinal cord Brain enclosed in skull and surrounded by a tough three-layer membrane called meninges The meninges forms the blood brain barrier – determines what chemicals reach the brain. Cerebrospinal Fluid.

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CNS General Structure

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  1. CNS General Structure • Composed of brain and spinal cord • Brain enclosed in skull and surrounded by a tough three-layer membrane called meninges • The meninges forms the blood brain barrier – determines what chemicals reach the brain

  2. Cerebrospinal Fluid • Circulates between two layers in the meninges and also in spinal cord • Functions: • Shock absorber • Transport medium • Spinal Tap – extraction of cerebrospinal fluid to diagnose infection

  3. Spinal Cord • Carries sensory nerve messages to the brain and motor nerve messages from the brain to effectors • Emerges from skull through opening called foramen magnum and extends down through canal in backbone

  4. Spinal Cord Organization • Two types of nerve tissue • White matter – myelinated nerve fibres from sensory and motor neurons • Grey matter – nonmyelinated interneurons • Interneurons form nerve tracts that connect spinal cord with brain • Dorsal nerve tract – sensory info into spinal cord • Ventral nerve tract – motor info from spinal cord to effectors

  5. The Brain

  6. Brain Structure • Three distinct regions: forebrain, midbrain and hindbrain • Forebrain contains: • Olfactory lobes – receive info about smell • Cerebrum – major coordinating centre • Two hemispheres • Contain regions associated with speech, reasoning, memory, and other higher functions • Surface called cerebral cortex – made of grey matter with many folds to increase surface area

  7. Lobes of the Cerebrum • Cerebral cortex divided into parts called lobes: • the frontal lobe • the parietal lobe • the temporal lobe • the occipital lobe

  8. The frontal lobe • is the center for voluntary movement • is called the “motor area” (movement) • includes the prefrontal area, for intelligence, creativity, memory, and personality.

  9. The parietal lobe Collects, recognizes, and organizes sensations: feelings of • pain • temperature • touch • position • movement

  10. The temporal lobe • processes auditory (hearing) information • stores auditory (hearing) and visual (seeing) memories

  11. The occipital lobe • is at the back of the cerebral hemisphere • involves • vision • visual memory • eye movements

  12. Cerebral Hemispheres • Two cerebral hemispheres are not mirror images of each other • Right side associated with visual patterns or spatial awareness • Left side linked to verbal skills • Some people may have one side more dominant which may affect the way they learn • Corpus callosum – bundle of nerve fibres connecting two hemispheres

  13. Midbrain • Less developed than forebrain • Consists of four spheres of grey matter • Mostly composed of tracts of nerve fibers • Relay centre for some eye and ear reflexes

  14. Hindbrain • Joins to spinal cord • Major regions: • Cerebellum • Largest section of hindbrain • Controls limb movements and balance • Pons • Relay station passes info between two regions of cerebellum • Medulla oblongata • Controls involuntary muscle action (breathing movements, heart rate, etc)

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