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Figure 11.17
Chemical synapses transmit
signals from one neuron to another
using neurotransmitters.
1
2
3
4
Action potential
arrives at axon terminal.
Voltage-gated Ca
2+
channels
open and Ca
2+
enters the axon
terminal.
Ca
2+
entry causes
synaptic vesicles to
release neurotransmitter
by exocytosis
Neurotransmitter diffuses
across the synaptic cleft and
binds to specific receptors on
the postsynaptic membrane.
5
Binding of neurotransmitter opens ion channels,
resulting in graded potentials.
6
Neurotransmitter effects are terminated
by reuptake through transport proteins,
enzymatic degradation, or diffusion away
from the synapse.
Ca
2+
Ca
2+
Ca
2+
Ca
2+
Synaptic
vesicles
Axon
terminal
Mitochondrion
Postsynaptic
neuron
Presynaptic
neuron
Presynaptic
neuron
Synaptic cleft
Ion movement
Graded potential
Reuptake
Enzymatic
degradation
Diffusion away
from synapse
Postsynaptic
neuron
FOCUS
Chemical Synapse
 
409
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