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Chapter 7

VPHY 3100 Chapter 7: chapter 7 Textbook notes for better understanding


Department
Physiology and Pharmacology
Course Code
VPHY 3100
Professor
Li
Chapter
7

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9/9/17 2:11 PM
Chapter 7 The Nervous System
Neurons and supporting cells
- nervous system is composed of neurons, which produce and conduct
electrochemical impulse, and supporting cells, which assist the functions of the
neurons
- Central Nervous system= brain and spinal cord
o Seven major parts of the CNS and three broad regions of the brain
- Peripheral nervous system= cranial nerves arising from the brain and the
spinal nerves arising from the spinal cord
- Two types of cells in the nervous system
Neurons: the basic structural and functional units/ cells of the nervous
system
Glial cells: supporting cells aid the functions of the neurons and are about
five times more abundant than neurons
- Functional class of neurons (based on the direction in which they conduct
impulses)
o Afferent neurons= sensory neuron: conduct impulses from sensory
receptors into the CNS- detect environment
o Efferent neurons= motor neurons: conduct impulses out of the CAN to
effectors organs (muscles and glands)- control what to do
§ Somatic motor neurons or autonomic motor neurons
- Nuclei: CNS supporting cells (oligodendrocytes, microglia and astrocytes)
- Ganglia/ glia: supporting cells of the PNS (Schwann cells and satellite cells/
ganglionic gliocytes)
- Axons turn into bundlesà form fibers: CNS= tract and Nerves= PNS
Nerve: bundle of axons located outside the CNS, bundle of axons in the
CNS is a tract

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- Classification of Neurons
functional
morphological
neurotransmitter released
Supporting Cells: Gila à predominant Glia of vertebrates
- Astrocytes (CNS)- SUPER IMPORTANT
Must abundant type of glial cell
Multiple functions via end- feed on capillaries and neurons
Help regulate the external environment of neurons in the CNS
Cover the capillaries of the CNS and induce the blood- brain barrier;
interact metabolically with neurons and modify the extracellular
environment of neurons
Glucose uptake from blood; lactate delivery to neurons
o Neurons need lactate to sustain high rate of aerobic cell respiration
o **astrocyte end- feet take up glucose from blood capillaries and
use this to help supply energy substrates for neurons. Astrocytes
take up glutamate from synapses and convert it into glutamate,
which is then recycled to the neurons

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K+ re- uptake
o K+ diffuses out of neurons during the production of nerve impulses,
this function is important in maintaining the proper ionic
environment for neurons
Glutamate/ Glutamine shuttle to resupply neurons with neurotransmitter
o Neurotransmitter glutamate is taken into astrocytes and
transformed into glutamine
o Glutamine is then released back into the neuron, and can be used
by other neurons to produce GABA
Synaptogenesis and neurogenesis
o Hippocampus
Establish and maintaining the blood-brain barrier
o Prevent particular molecules in the plasma from entering the
central nervous system
- Oligodendrocytes ( CNS)
insulation of central axons
myelin sheath (“white matter”)
o unlike a Schwann cell which forms a myelin sheath around only one
axon, each oligondendrocyte has extensions, like the tentacles of
an octopus, that form myelin sheaths around several axons
o the myelin sheaths around axons of the CNS give this tissue a
white color; gray matter of the CNS is composed of high
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