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Central Nervous System

At the center of everything… but separated by layers of membranes. Central Nervous System. It’s all about connections…. Brain  spinal cord via foramen magnum Spinal cord runs through vertebral canal, formed by vertebral foramina. Meninges mater (umm… matter ).

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Central Nervous System

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  1. At the center of everything… but separated by layers of membranes Central Nervous System

  2. It’s all about connections… • Brain  spinal cord via foramen magnum • Spinal cord runs through vertebral canal, formed by vertebral foramina

  3. Meninges mater (umm… matter) • Dura mater – “durable” tough, dense; protection from impact, friction • Arachnoid mater – cushion from impact • Subarachnoid space – CSF runs here • Pia mater – in the “pits” • direct contact • Carries blood vessels • Forms nerve sheaths • Helps form CSF

  4. More on the pia mater • Associated with choroid plexus • Secretes CSF • Combination of blood vessels & neuroglia • Remember which kind? Ependymal cells

  5. It’s not all black and white… but it is gray! • Gray matter = unmyelinated neuron cell bodies • Accumulate lipofuscin • Found primarily in cortex (surface of brain) • Highly folded/ridged = gyri • Increase surface area • Small pockets of gray found in interior • White matter = myelinated axons, neuroglia • Found in brain’s interior • In spinal cord, colors are reversed… outside white, inside gray

  6. Concept check! • 1. Describe the three layers of the meninges • 2. What is the function of the choroid plexus? • 3. Describe the locations of gray and white matter in the CNS • Why are they those colors?

  7. The Brain

  8. Three-Pound Marvel: The Brain • Billions of neurons, neuroglia • Most multipolar (1 axon, many dendrites) • Receive many signals, process them • Tracts of axons • Information conduit  other regions of brain, body

  9. Forebrain: Cerebrum and diencephalon • Largest, most anterior portion • Emotions • Memory • Motor movement • Thought • Contain basal nuclei, cerebral cortex

  10. Forebrain: Basal nuclei/ganglia • 4 pockets of gray matter – relay motor information to spinal cord • Permit coordinated, steady body movements

  11. Cerebral cortex • Convoluted gray matter covering brain • Large surface area (18 sq ft.)

  12. Blood-brain barrier • Cerebral cortex nourished by vessels in arachnoid layer • “Barrier” exists between bloodstream and CSF… Which neuroglia create this? • Astrocytes! • Prevents harmful substances from entering brain (also medications)

  13. Cerebral Hemispheres • Halves of cerebrum divided by longitudinal cerebral fissure • Some division of labor… • But you use both halves!

  14. Communication between hemispheres • Corpus callosum connects left and right hemispheres • Contributes to plasticity of brain

  15. Four lobes of the cerebrum Central sulcus Lateral sulcus

  16. Brain stem?

  17. Areas of specialization

  18. Deep, medial portion • Hypothalamus, thalamus, ventricles

  19. Thalamus • Sensation, spatial sense, motor signals to cortex • Surrounds 3rd ventricle

  20. Hypothalamus • Link nervous system to endocrine system via pituitary gland

  21. Ventricles • 4 connected cavities in the forebrain that contain CSF • Associated w/ choroid plexus, continue into spinal cord • Protect brain from trauma • Internal cushion • Swelling: hydrocephaly

  22. Brainstem: Midbrain & Hindbrain

  23. Midbrain • Strip of neurons, connects cerebrum to hindbrain. • Smallest region of the brain • Relay station for audio and visual info • Eye movement • Substantianigra: dopamine neurons

  24. Hindbrain

  25. Pons • Attached to midbrain • Organize & transmit sensory info from the body

  26. Medulla oblongata • Reg’s involuntary body functions • BP • Breathing • Heart rate • Swallowing

  27. Cerebellum • Posterior to pons • Means “little cerebrum” • In appearance only • Balance • Posture • Coordination of body movement

  28. The Spinal Cord

  29. Spinal Cord • Where does it start from? (picture) • Paper towel roll • Blanket • Model of spine

  30. White matter • 15 pairs nerve tracts • Ascending tracts • Dorsal • Sensory to the brain • Descending tracts • Lateral & ventral • Motor info to effectors • Extrapyramidal tracts • Info from medulla oblongata  posture & muscle tone

  31. Gray matter • Made of nerve cell bodies reflexes • Transfer info to white matter • Dorsal horn • sensory • Ventral horn • Motor • White mattermuscles • Intermediate gray matter • b/t “wings” • Sensory/motor for glands/muscles

  32. Spinal nerves • 31 pairs spinal nerves • Part of PNS • Reflex arcs for respective body regions

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