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The Central Nervous System

02 Nov. 2009. CNS1.ppt. 2. Development of the CNS. Similar in all "Amniotes"Blastoderm over yolk sacthree "germ layers"Ectoderm ("outside skin")Mesoderm ("middle skin")Endoderm ("inner skin"). 02 Nov. 2009. CNS1.ppt. 3. Nervous System Development. Develops from Ectoderm Rising of neural folds

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The Central Nervous System

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    1. 02 Nov. 2009 CNS1.ppt 1 The Central Nervous System Brain & Spinal cord

    2. 02 Nov. 2009 CNS1.ppt 2 Development of the CNS Similar in all "Amniotes" Blastoderm over yolk sac three "germ layers" Ectoderm ("outside skin") Mesoderm ("middle skin") Endoderm ("inner skin")

    3. 02 Nov. 2009 CNS1.ppt 3 Nervous System Development Develops from Ectoderm Rising of neural folds Sinking of neural plate forms neural groove Folds fuse to complete neural tube

    4. 02 Nov. 2009 CNS1.ppt 4 Nervous System Development Neural tube forms CNS (esp. spinal cord) Expands anteriorly to form brain Peripheral nerves develop from lateral "neural crest" cells

    5. 02 Nov. 2009 CNS1.ppt 5 Expansion of Brain Primary Forebrain Midbrain Hindbrain

    6. 02 Nov. 2009 CNS1.ppt 6 Expansion of Brain Secondary Forebrain Telencephalon Diencephalon Midbrain remains just midbrain Hindbrain Cerebellum Brain stem

    7. 02 Nov. 2009 CNS1.ppt 7 Expansion of Brain Final development Telencephalon = cerebrum Diencephalon = thalamus + hypothalamus Cerebellum Brain stem = Midbrain + pons + medulla oblongata

    8. 02 Nov. 2009 CNS1.ppt 8 Protection & Nutrition of CNS

    9. 02 Nov. 2009 CNS1.ppt 9 Protection Bone Cranial bones & vertebral arches Meninges Dura mater Arachnoid mater Pia mater Cerebrospinal fluid (CSF)

    10. 02 Nov. 2009 CNS1.ppt 10 Meninges Dura mater Arachnoid mater Pia mater

    11. 02 Nov. 2009 CNS1.ppt 11 Cerebrospinal fluid (CSF) Filtered from blood plasma in choroid plexuses

    12. 02 Nov. 2009 CNS1.ppt 12 Cerebrospinal fluid (CSF) Filtered from blood plasma in choroid plexuses Circulates in through ventricles, canals, & between meninges Returned to blood at superior sagittal sinus

    13. 02 Nov. 2009 CNS1.ppt 13 Ventricles of the Brain 2 Lateral ventricles (1, 2) in cerebral hemispheres Third ventricle (3) between hemispheres Fourth ventricle (4) in midbrain and medulla

    14. 02 Nov. 2009 CNS1.ppt 14 Cerebrospinal fluid (CSF) Supports (buoys) mass Cushions CNS - like waterbed Nourishes brain tissue Contains proper electrolytes for CNS

    15. 02 Nov. 2009 CNS1.ppt 15 Blood supply & Nutrition Brain is highly vascular blood delivers O2 and glucose supply Can't be deprived of O2. No capacity for anaerobic respiration. Brain cells die w/in 5-6 minutes when deprived Requires glucose (or ketone bodies) as fuel Can't use fats, amino acids.

    16. 02 Nov. 2009 CNS1.ppt 16 Blood-brain barrier CNS is sensitive to chemicals Capillaries have thicker, non-leaky walls. Protects brain from drugs, metabolites, toxins

    17. 02 Nov. 2009 CNS1.ppt 17 BRAIN Largest part of CNS Center of consciousness, communication Integrates sensory input Coordinates complex responses to environment Center of homeostatic regulation of nearly all physiological processes. Breathing, Heartbeat, Hunger/Satiety Reproductive "drive," Musculoskeletal coordination

    18. 02 Nov. 2009 CNS1.ppt 18 Parts of the Brain In order evolved, from lower posterior to higher anterior.

    19. 02 Nov. 2009 CNS1.ppt 19 Brain Stem Superior continuation of spinal cord Medulla oblongata Pons (bridge) Midbrain Reticular formation

    20. 02 Nov. 2009 CNS1.ppt 20 Medulla oblongata Conduction region for motor and sensory pathways to & from brain Decussation Crossing of tracts/fibers to opposite sides Left brain controls right motor activity. Regulation of heartbeat & force of contraction, " " breathing rhythm, " " blood flow through arteries, " " equilibrium (sense of balance). Origins of cranial nerves VIII - XII

    21. 02 Nov. 2009 CNS1.ppt 21 Pons (bridge) Connections to other parts of brain transverse fibers to/from cerebellum longitudinal fibers to above/below Regulation of breathing Origins of cranial nerves V - VIII

    22. 02 Nov. 2009 CNS1.ppt 22 Midbrain Conveys impulses to/from cerebrum  Superior & Inferior colliculi Reflex centers for movements of eyes, head, & torso in response to visual & auditory stimuli Tracking of moving objects Origins of cranial nerves III, IV

    23. 02 Nov. 2009 CNS1.ppt 23 Reticular formation Deep structure of whole brain stem Reticular Activating System Regulates alertness, wakefulness & sleep

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