CENTRAL NERVOUS SYSTEM At the center of everything… but separated by layers of membranes
Dec 14, 2015
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) 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
More on the pia mater
Associated with choroid plexusSecretes CSFCombination of blood vessels & neuroglia
○ Remember which kind?
Ependymal cells
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
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?
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
Forebrain: Cerebrum and diencephalon Largest, most anterior portion
EmotionsMemoryMotor movementThought
Contain basal nuclei, cerebral cortex
Forebrain: Basal nuclei/ganglia 4 pockets of gray matter – relay motor
information to spinal cordPermit coordinated, steady body
movements
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)
Cerebral Hemispheres
Halves of cerebrum divided by longitudinal cerebral fissure
Some division of labor… But you use both halves!
Communication between hemispheres Corpus callosum connects left and
right hemispheresContributes to plasticity of brain
Ventricles
4 connected cavities in the forebrain that contain CSF
Associated w/ choroid plexus, continue into spinal cord
Protect brain from traumaInternal cushion
Swelling: hydrocephaly
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
Cerebellum
Posterior to pons Means “little cerebrum”
In appearance only Balance Posture Coordination of body movement
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
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