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CENTRAL NERVOUS SYSTEM (SPINAL CORD (White matter ((consists of myelinated…
CENTRAL NERVOUS SYSTEM
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NEURONS
Commonly called afferent fiber, extends from receptor to the cell body
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GLIAL CELLS
-90% of the cells in the CNS
-communicate with neurons
and among themselves by chemical signals
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Microglia
Defense the brain as scavenger (immune defense cells of CNS) and release nerve growth factor to help neurons and other glial cells survive
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BRAIN
Brain stem (medulla, pons, midbrain, and diencephalon)
oldest part that controls heart & respiration rates, motor reflexes
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Cerebellum ((frontal, parietal, temporal, and occipital lobes)
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SPINAL CORD
long (about 45 cm), slender cylinder (2 cm in diameter) of nerve tissue that extends from the brain stem
Pair spinal nerves emerge from the spinal cord formed between the bony, winglike arches of adjacent vertebrae
The spinal cord extends only to the level of the first or second lumber vertebra (about waist level)
White matter
consists of myelinated nerve cell bodies, composed of tracts of axons carrying information to and from the brain. Ascending tracts take sensory information to the brain. Descending tracts carry efferent signals from the brain to the cord.
Gray Matter
consists of unmyelinated nerve cell bodies, dendrites, axon terminals. Sensory fibers from the dorsal roots synapse with interneuron in the dorsal horns. The ventral horns are organized into somatic motor and autonomic nuclei. Efferent fibers leave the spinal cord via ventral root.