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Dopamine (DA) neuron

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SYNTHESIS- neurotransmitter is produced by enzymes. STORAGE- stored in vesicles ... from a pre-release state. into a fusion with release. sites on the membrane. ... – PowerPoint PPT presentation

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Title: Dopamine (DA) neuron


1
axons
Dendrites
terminals
Cell body (Soma)
Dopamine (DA) neuron
2
Most information comes in here
axons
Dendrites
terminals
Cell body (Soma)
Dopamine (DA) neuron
3
Chemical signals Generate EPSPs Or IPSPs
axons
terminals
Cell body (Soma)
Dopamine (DA) neuron
4
If excitation caused By EPSPs is great Enough to
cross the threshold, An Action Potenial is
generated.
axons
terminals
Cell body (point of origin)
Dopamine (DA) neuron
5
Action Potentials travel along the axon
axons
terminals
Cell body (point of origin)
Dopamine (DA) neuron
6
AXON
Towards terminals
Towards soma
7
Excitation above the threshold Opens
Voltage-gated Na channels
Na
AXON
Towards terminals
Towards soma
8
Na ions rush into cell, causing Action Potential
(ascending limb)
Na
Na Na Na
AXON
Towards terminals
Towards soma
9
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
K moves out To restore resting Potential (i.e.,
Descending limb)
AXON
Towards terminals
Towards soma
10
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
11
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
12
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
13
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
14
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
15
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
16
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
17
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
18
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
19
Action Potential is propagated down The Axon
K
Na
Na Na Na
K
AXON
Towards terminals
Towards soma
20
Action Potentials travel along the axon
axons
terminals
Cell body (point of origin)
Dopamine (DA) neuron
21
axons
terminals
Cell body (point of origin)
Dopamine (DA) neuron
22
axons
terminals
Cell body (point of origin)
Dopamine (DA) neuron
23
axons
terminals
Cell body (point of origin)
Dopamine (DA) neuron
24
axons
terminals
Cell body (point of origin)
Dopamine (DA) neuron
25
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axons
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causing neurotransmitter release from the
terminals
Cell body (point of origin)
Dopamine (DA) neuron
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axons
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causing neurotransmitter release from the
terminals
Cell body (point of origin)
Dopamine (DA) neuron
27
Stages of Synaptic Transmission
  • SYNTHESIS- neurotransmitter is produced by
    enzymes
  • STORAGE- stored in vesicles
  • RELEASE- released into the synapse
  • POSTSYNAPTIC ACTION- acts on postsynaptic
    receptors
  • INACTIVATION- broken down by enzymes or taken up
    into cells

28
SYNAPSE Point of functional connection
DA terminal
  • Transmitter is
  • synthesized from a
  • precursor molecule by
  • enzymes in the
  • presynaptic cell


Synaptic cleft
Postsynaptic cell
29
SYNAPSE Point of functional connection
DA terminal
2. Transmitter is stored in presynaptic vesicles

Synaptic cleft
Postsynaptic cell
30
Electrical impulse action potential
DA terminal

Synaptic cleft
Postsynaptic cell
31
DA terminal
Synaptic cleft
Postsynaptic cell
32
DA terminal
Ca
3. Release. Action Potential opens voltage- Gated
Ca channels
Synaptic cleft
Postsynaptic cell
33
DA terminal
Ca
Ca
Ca
Ca
3. Release. There is an influx of Ca into
the terminal
Synaptic cleft
Postsynaptic cell
34
DA terminal
3. Ca influx promotes several processes
that lead the vesicles to go from a pre-release
state into a fusion with release sites on the
membrane. Transmitter is released
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Synaptic cleft
Postsynaptic cell
35
DA terminal
.
Transmitter diffuses across synaptic cleft
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Synaptic cleft
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Postsynaptic cell
36
DA terminal
Transmitter diffuses across synaptic cleft
.
Synaptic cleft
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Postsynaptic cell
37
DA terminal
4. Postsynaptic Action. a) Transmitter binds to
postsynaptic receptors
.
Synaptic cleft
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DA Receptor proteins
Postsynaptic cell
38
DA terminal
4. Postsynaptic Action. b) Transmitter
binding induces intrinsic biological activity
(i.e. signal transduction effects)
in postsynaptic cell.
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.
Synaptic cleft
.
Physiological and biochemical effects (EPSPs or
IPSPs)
Postsynaptic cell
39
DA terminal
.
  • 5. Inactivation.
  • Transmitter is transported back into presynaptic
    terminal
  • by protein transporter (i.e.,
  • uptake or reuptake).

.
.
Synaptic cleft

Postsynaptic cell
40
DA terminal
5. Inactivation. b) Transmitter is broken down
(i.e. metabolized) by enzymes.
.
Synaptic cleft
.

Postsynaptic cell
41
STUDIES OF THE BEHAVIORAL EFFECTS OF DRUGS
  • DRUGS MODIFY THE PROCESS OF CHEMICAL TRANSMISSION
    IN THE NERVOUS SYSTEM
  • Alter neurotransmitter synthesis
  • Block storage of transmitter
  • Stimulate or reduce release
  • Stimulate or block receptors
  • Block the enzymatic breakdown or uptake of
    transmitter
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