Central Nervous System
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Transcript of Central Nervous System
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CENTRAL NERVOUS SYSTEM
At the center of everything… but separated by layers of membranes
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It’s all about connections… Brain spinal cord via foramen
magnum Spinal cord runs through vertebral canal,
formed by vertebral foramina
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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 contactCarries blood vessels Forms nerve sheathsHelps form CSF
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More on the pia mater Associated with choroid plexus
Secretes CSFCombination of blood vessels & neuroglia
○ Remember which kind? Ependymal cells
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It’s not all black and white… but it is gray! Gray matter = unmyelinated neuron cell
bodiesAccumulate lipofuscinFound primarily in cortex (surface of brain)
○ Highly folded/ridged = gyriIncrease 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
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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 CNSWhy are they those colors?
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The Brain
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Three-Pound Marvel: The Brain Billions of neurons, neuroglia
Most multipolar (1 axon, many dendrites)Receive many signals, process them
Tracts of axonsInformation conduit other regions of brain,
body
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Forebrain: Cerebrum and diencephalon Largest, most anterior portion
EmotionsMemoryMotor movementThought
Contain basal nuclei, cerebral cortex
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Forebrain: Basal nuclei/ganglia 4 pockets of gray matter – relay motor
information to spinal cordPermit coordinated, steady body
movements
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Cerebral cortex Convoluted gray matter covering brain Large surface area (18 sq ft.)
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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)
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Cerebral Hemispheres Halves of cerebrum divided by
longitudinal cerebral fissure Some division of labor…
But you use both halves!
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Communication between hemispheres Corpus callosum connects left and
right hemispheresContributes to plasticity of brain
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Four lobes of the cerebrum
Central sulcus
Lateral sulcus
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Brain stem?
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Areas of specialization
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Deep, medial portion Hypothalamus, thalamus, ventricles
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Thalamus Sensation, spatial
sense, motor signals to cortex
Surrounds 3rd ventricle
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Hypothalamus Link nervous
system to endocrine system via pituitary gland
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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
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Brainstem: Midbrain & Hindbrain
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Midbrain Strip of neurons, connects cerebrum to hindbrain.
Smallest region of the brain
Relay station for audio and visual info
Eye movement Substantia nigra:
dopamine neurons
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Hindbrain
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Pons Attached to midbrain Organize & transmit sensory info from
the body
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Medulla oblongata Reg’s involuntary body functions
BPBreathingHeart rateSwallowing
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Cerebellum Posterior to pons Means “little cerebrum”
In appearance only Balance Posture Coordination of body movement
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The Spinal Cord
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Spinal Cord Where does it
start from? (picture)
Paper towel roll Blanket Model of spine
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White matter15 pairs nerve tractsAscending tracts
○ Dorsal○ Sensory to the brain
Descending tracts○ Lateral & ventral○ Motor info to
effectorsExtrapyramidal tracts
○ Info from medulla oblongata posture & muscle tone
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Gray matter Made of nerve cell
bodies reflexes Transfer info to white
matter Dorsal horn
sensory Ventral horn
MotorWhite mattermuscles
Intermediate gray matterb/t “wings”Sensory/motor for
glands/muscles
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Spinal nerves 31 pairs spinal nerves Part of PNS Reflex arcs for respective body regions