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•Star-like appearance
•Development of connections between nervous and non-nervous tissue
•Blood-brain barrier
•Remove neurotransmitters (e.g., glutamate) from synaptic cleft: high glutamate toxic
•Maintain normal electrolyte composition of interstitial fluid in CNS, especially K+
•Protect neurons against toxic substances and oxidative stress |
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•Function with astrocytes to protect neurons from toxic substances
•Protect the CNS from foreign matter through phagocytosis
–Bacteria
–Dead or injured cells
•Protect the CNS from oxidative stress |
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Definition
•Myelin forming cells
•One oligodendrocyte:
–Forms several myelin sheaths
–Myelinates sections of several axons |
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(CSF)
•Clear watery fluid bathing the CNS
•Secreted by ependymal cells of the choroid plexus
–Circulates through ventricles to subarachnoid space
–Reabsorbed by arachnoid villi
•Functions
–Cushions the brain
–Maintains a stable interstitial fluid environment
•Total volume of CSF = 125–150 mL
•Choroid plexus produces 400–500 mL/day
•Recycled three times per day |
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•Typical Capillaries
–Sites of exchange between blood and interstitial fluid
–Thin: single layer of endothelial cells
–Diffusion
–Special anatomy consisting of CNS capillaries that limit exchange |
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Cell Bodies
functional halves
–Dorsal: sensory functions
–Ventral: motor functions
•Spinal nerves are mixed |
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Definition
–Projection fibers
•Connect cerebral cortex with lower levels of brain or spinal cord
–Association fibers
•Connect two areas of cerebral cortex on same side of brain
–Commissural fibers
•Connect same cortical regions on two sides of brain
–Corpus callosum
•Primary location of commissural fibers |
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Definition
•Lateral Spinothalamic Tract
–Ascending Pathway
–Originates with sensory receptors in the peripheral nervous system
–The spinothalamic tract crosses to the contralateral side in the spinal cord
•Decussate
–Travels up the spinal cord eventually communicating sensory information to the thalamus and then the cerebral cortex |
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Definition
•Both Pyramidal Tracts originate in the primary motor cortex.
•The lateral tract crosses over in the medullary pyramids while the anterior pyramidal tracts crosses over in the spinal cord.
•Both tracts terminate in the ventral horn of the spinal cord where they communicate to motor neurons innervating skeletal muscle. |
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