Transcript Figure 11.3 Neuroglia.

Figure 11.3 Neuroglia.
Capillary
Neuron
Astrocyte
Astrocytes are the most abundant CNS neuroglia.
Neuron
Microglial
cell
Microglial cells are defensive cells in the CNS.
Fluid-filled cavity
Cilia
Ependymal
cells
Brain or
spinal cord
tissue
Ependymal cells line cerebrospinal fluid–filled cavities.
Myelin sheath
Process of
oligodendrocyte
Nerve
fibers
Oligodendrocytes have processes that form myelin
sheaths around CNS nerve fibers.
Satellite
cells
Cell body of neuron
Schwann cells
(forming myelin sheath)
Nerve fiber
Satellite cells and Schwann cells (which form myelin)
surround neurons in the PNS.
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Figure 11.3a Neuroglia.
Capillary
Neuron
Astrocyte
Astrocytes are the most abundant CNS neuroglia.
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Figure 11.3b Neuroglia.
Neuron
Microglial
cell
Microglial cells are defensive cells in the CNS.
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Figure 11.3c Neuroglia.
Fluid-filled cavity
Cilia
Ependymal
cells
Brain or
spinal cord
tissue
Ependymal cells line cerebrospinal fluid–filled cavities.
© 2014 Pearson Education, Inc.
Figure 11.3d Neuroglia.
Myelin sheath
Process of
oligodendrocyte
Nerve
fibers
Oligodendrocytes have processes that form myelin
sheaths around CNS nerve fibers.
© 2014 Pearson Education, Inc.
Figure 11.3e Neuroglia.
Satellite
cells
Cell body of neuron
Schwann cells
(forming myelin sheath)
Nerve fiber
Satellite cells and Schwann cells (which form myelin)
surround neurons in the PNS.
© 2014 Pearson Education, Inc.
Figure 11.4 Structure of a motor neuron.
Dendrites
(receptive
regions)
Neuron cell body
Cell body
(biosynthetic center
and receptive region)
Nucleus
Axon
(impulse-generating
and -conducting
region)
Nucleolus
Chromatophilic
substance (rough
endoplasmic
reticulum)
Axon hillock
Dendritic
spine
Impulse
direction
Myelin sheath gap
(node of Ranvier)
Schwann cell
Terminal branches
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Axon terminals
(secretory
region)
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Table 11.1 Comparison of Structural Classes of Neurons (2 of 3)
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Figure 11.16b Synapses.
Axon
Axosomatic
synapses
Cell body (soma)
of postsynaptic
neuron
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Figure 11.11 The action potential (AP) is a brief change in membrane potential in a “patch” of membrane that is
depolarized by local currents. (3 of 11)
The big picture
Membrane potential (mV)
1 Resting state
2 Depolarization
+30
3
3 Repolarization
0
Action
potential
2
Threshold
–55
–70
1
0
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4 Hyperpolarization
1
4
1
2
3
Time (ms)
4
Figure 11.17 Chemical synapses transmit signals from one neuron to another using neurotransmitters. (1 of 3)
Presynaptic
neuron
Presynaptic
neuron
Postsynaptic
neuron
1 Action potential
arrives at axon
terminal.
2 Voltage-gated Ca2+
channels open and Ca2+
enters the axon terminal.
3 Ca2+ entry
causes synaptic
vesicles to release
neurotransmitter
by exocytosis
4 Neurotransmitter diffuses
across the synaptic cleft and
binds to specific receptors on
the postsynaptic membrane.
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Mitochondrion
Synaptic
cleft
Axon
terminal
Synaptic
vesicles
Postsynaptic
neuron
Membrane potential (mV)
Figure 11.18 Postsynaptic potentials can be excitatory or inhibitory.
+30
0
Threshold
–55
–70
An EPSP is a local
depolarization of the
postsynaptic membrane
that brings the neuron
closer to AP threshold.
Neurotransmitter binding
opens chemically gated
ion channels, allowing
Na+ and K+ to pass
through simultaneously.
Stimulus
10
20
30
Time (ms)
Membrane potential (mV)
Excitatory postsynaptic potential (EPSP)
+30
0
Threshold
An IPSP is a local
hyperpolarization of the
postsynaptic membrane
that drives the neuron
away from AP threshold.
Neurotransmitter binding
opens K+ or Cl– channels.
–55
–70
Stimulus
10
20
30
Time (ms)
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Inhibitory postsynaptic potential (IPSP)