BIOL 1410 Lecture Notes - Lecture 19: Central Nervous System, Multipolar Neuron, Unipolar Neuron

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TOPIC 19: NERVOUS SYSTEM
A) Nervous System: Overview
2 divisions:
1) Central Nervous System (CNS)
oad center or otrol eter
brain + spinal cord
processes + integrates info
2) Peripheral Nervous System (PNS) figure 13.7 & 13.29
consists of:
a) cranial nerves
to/from brain
b) spinal nerves
to/from spinal cord
2 divisions of PNS: figure 11.1
a) sensory/afferent division enters
has sensory receptors that detect stimuli (change in internal or
external environments)
b) motor/efferent division
nerves convey impulses away from CNS exits
innervates (supplies signals/nerves to) effectors = muscles +
glands (endocrine or exocrine)
relationship between CNS and PNS:
example:
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Nervous System Organization: figure 11.2
B) Nervous System: Histology
Cell Types:
1) Neurons
conduct impulses
make up CNS + PNS
mostly amitotic (irreplaceable) you cant make more of them
o exceptions = taste, olfaction, memory
structure:
a) cell body
typical organelles
RER called - Nissl Bodies
groups/clusters in CNS = nuclei (gray matter)
groups/clusters in PNS = ganglia
b) processes from cell body:
i. dendrites
receive incoming messages + relay to cell body
ii. axon
carry impulses away from cell body
axon hillock = where axon meets cell body
axon terminal = typically branched with synaptic end
bulbs (enlarged tips)
may be:
myelinated - wrapped in many layers of cell
membrane from Schwann cells (PNS) or
oligodendrocytes (CNS)
electrical insulation
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gaps in myelin sheath are called Nodes of
Ranvier
myelinated axon bundles in:
o CNS = tracts (white matter)
o PNS = nerves
o BE ABLE TO ANSWER THESE
QUESTION FOR THE EXAMS
unmyelinated no myelin
2) Neuroglia (glial cells)
Surround and support neuron cells = can undergo mitosis (prone to cancer
brain tumor)
types:
a) CNS neuroglia
i. oligodendrocytes
produce myelin around axon
ii. microglia
protective become phagocytic if detect infected, dead,
or damaged neurons (because iue ells at eter
CNS)
iii. astrocytes
surround blood capillaries to form part of blood brain
barrier (BBB)
help control capillary permeability
iv. ependymal neural epithelia
line brain ventricles + central canal of the spinal cord
secrete cerebrospinal fluid (CSF) + circulate it (cilia)
b) PNS neuroglia
i. Schwann cells
form myelin around axons in PNS
ii. Satellite cells
surround neuron cell bodies in ganglia protection +
support
Neuron Classification:
1) Structural/Anatomical types:
based on # of cell processes off of cell body
a) Unipolar
1 process that divides into two: central + peripheral
peripheral end has dendrites = sensory receptors (pain, touch
etc) - remainder is axon
always sensory
b) Bipolar
2 processes: 1 axon, 1 process with dendrites
sensory retina, nose (olfaction)
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Document Summary

Topic 19: nervous system: nervous system: overview. 2 divisions: central nervous system (cns) Processes + integrates info: peripheral nervous system (pns) figure 13. 7 & 13. 29. Consists of: cranial nerves to/from brain, spinal nerves to/from spinal cord. 2 divisions of pns: figure 11. 1: sensory/afferent division enters. Has sensory receptors that detect stimuli (change in internal or external environments: motor/efferent division. Nerves convey impulses away from cns exits innervates (supplies signals/nerves to) effectors = muscles + glands (endocrine or exocrine) Nervous system organization: figure 11. 2: nervous system: histology. Mostly amitotic (irreplaceable) you cant make more of them: exceptions = taste, olfaction, memory. Groups/clusters in cns = nuclei (gray matter) Groups/clusters in pns = ganglia: processes from cell body, dendrites. Receive incoming messages + relay to cell body: axon. Axon hillock = where axon meets cell body. Axon terminal = typically branched with synaptic end bulbs (enlarged tips)

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