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Presynaptic
Axon Terminal
Terminal
Button
Postsynaptic
Membrane
Dendritic
Spine
(1) Precursor
Transport
(2)
Synthesis
_
_
_
enzymes/cofactors
NT
(3) Storage
in vesicles
NT
Terminal
Button
Dendritic
Spine
Synapse
Vesicles
(4) Release
Terminal
Button
Dendritic
Spine
Synapse
Receptors
Terminal
Button
AP
Dendritic
Spine
Synapse
Exocytosis
2+
Ca
(5) Activation
Quantum release
Each vesicle contains one quanta of
neurotransmitter (approximately 5000 molecules)
– quanta release
(3) Transmitter Inactivation
1.
2.
3.
4.
5.
6.
Reuptake by presynaptic terminal
Uptake by glial cells
Enzymatic degradation
Presynaptic receptor
Diffusion
Combination of above
(6) Termination
(1) Termination by...
Diffusion
(2) Termination by...
Enzymatic degradation
(3) Termination by...
• Reuptake by presynaptic terminal
• Uptake by glial cells
(4) Termination by...
Autoreceptors
A
2. Receptor Activation
NS uses 40 families , act on 100 types of
receptors; cause EPSPs and IPSPs,
Neuromodulators cause, via 2nd messengers, mor
complex metabolic effects in the PSM.
Ionotropic channel
– directly controls channel
– fast
• Metabotropic channel
– second messenger systems
(1) Ionotropic Channels
Channel
NT
neurotransmitter
Ionotropic Channels
NT
Pore
Ionotropic Channels
NT
Ionotropic Channels
G protein: Protein Phosphorylation
external
external signal:
signal: NT
nt
norepinephrine
Receptor
b adrenergic -R
transducer
primary
effector
GS
adenylyl
cyclase
2d messenger
cAMP
secondary effector
protein kinase
G protein: Protein Phosphorylation
A
C
R
G
GDP
PK
G protein: Protein Phosphorylation
A
C
R
G
ATP
GTP
cAMP
PK
G protein: Protein Phosphorylation
A
C
R
G
ATP
GTP
P
cAMP
PK
Pore