PHIL 1000X Final: Neural Physiology
10 May 2018
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Department
Course
Professor
BLOCK XB
MODULE X6 - NEURAL PHYSIOLOGY
UNIT 3
Central Nervous System
Unit Objectives
When you have finished this unit, you should be able to:
1. Explain the difference between a neuron and a nerve, between a nerve and a pathway
(tract), between a tract and a nuclei, and between white matter and grey matter.
a. GREY MATTER - consists of unmyelinated nerve cell bodies, dendrites, and
axons. The cell bodies are assembled in an organized fashion in both the brain
and the spinal cord. They form layers in some parts of the brain and in other
parts cluster into groups of neurons that have similar functions. Clusters of cell
bodies in the brain and spinal cord are known as nuclei
. Nuclei are usually
identified by specific names—for example, the lateral geniculate nucleus
, where
visual information is processed.
b. WHITE MATTER - is mostly myelinated axons and contains very few cell bodies.
Its pale color comes from the myelin sheaths that surround the axons. Bundles of
axons that connect different regions of the CNS are known as tracts. Tracts in
the central nervous system are equivalent to nerves in the peripheral nervous
system.
2. Sketch a cross-section of the spinal cord, label it, and briefly describe the structure of the
spinal cord. Include the dorsal and ventral horns, dorsal and ventral roots and the dorsal
root ganglion.
a. Ventral horns - of the gray matter contain cell bodies of motor neurons that carry
efferent signals to muscles and glands
b. Dorsal roots carry sensory or afferent info to CNS
c. Ventral roots carry motor or efferent info to muscles and glands
3. Differentiate between ascending, descending and propriospinal tracts.
i. Prop - tracts of white matter that remain within the cord
ii. Ascending - Spinal neurons that carry sensory info to the brain
1. Occupy dorsal & external lateral portions of the SC
iii. Descending - neurons that carry efferent (motor) neurons from brain to
SC
1. Occupy ventral and interior lateral portions of the white matter
Document Summary
The cell bodies are assembled in an organized fashion in both the brain and the spinal cord. They form layers in some parts of the brain and in other parts cluster into groups of neurons that have similar functions. Clusters of cell bodies in the brain and spinal cord are known as nuclei . Nuclei are usually identified by specific names for example, the lateral geniculate nucleus , where visual information is processed: white matter - is mostly myelinated axons and contains very few cell bodies. Its pale color comes from the myelin sheaths that surround the axons. Bundles of axons that connect different regions of the cns are known as tracts . Tracts in the central nervous system are equivalent to nerves in the peripheral nervous system: sketch a cross-section of the spinal cord, label it, and briefly describe the structure of the spinal cord.
