presynaptic axon terminal postsynaptic membrane terminal button dendritic spine

PresynapticAxon Terminal

PostsynapticMembrane

Terminal Button Dendritic

Spine

(1) Precursor Transport

_ _ _

NT

(2) Synthesis

enzymes/cofactors

(3) Storage

in vesicles

Synapse

Vesicles

NT

Terminal Button

Dendritic Spine

Synapse

Terminal Button

Dendritic Spine

(4) Release

Receptors

Synapse

Terminal Button

Dendritic Spine

AP

Ca2+

Exocytosis

(5) Activation

Quantum releaseEach vesicle contains one quanta of

neurotransmitter (approximately 5000 molecules) – quanta release

(3) Transmitter Inactivation

1. Reuptake by presynaptic terminal2. Uptake by glial cells3. Enzymatic degradation4. Presynaptic receptor5. Diffusion6. 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 ActivationNS uses 40 families , act on 100 types of receptors; cause EPSPs and IPSPs,

Neuromodulators cause, via 2nd messengers, more complex metabolic effects in the PSM.

Ionotropic channel– directly controls channel– fast

• Metabotropic channel– second messenger systems– receptor indirectly controls channel ~

(1) Ionotropic ChannelsneurotransmitterNTChannel

Ionotropic Channels

NT

Pore

Ionotropic Channels

NT

Ionotropic Channels

NT

G protein: Protein Phosphorylation

Receptor

trans-ducer

primaryeffector

external signal: nt

2d messenger

secondary effector

Receptor

trans-ducer

primaryeffector

external signal: NT

2d messenger

secondary effector

GS

norepinephrine

cAMP

protein kinase

b adrenergic -R

adenylylcyclase

G protein: Protein Phosphorylation

RG

GDP

AC

PK

G protein: Protein Phosphorylation

R

AC

PK

G

GTP

ATP

cAMP

G protein: Protein Phosphorylation

R

AC

PK

G

GTP

ATP

cAMP

P

Pore