Download Synapses

Excitatory
A/P
The origin of an action
potential
Leads to an
action potential
in the post-synaptic
neuron
At the axon
hillock
The origin of an action
potential
Does not lead to an
action potential
in the post-synaptic
neuron
Inhibitory
A/P
The origin of an action
potential
Excitatory
The two types of
potential can cancel
each other out…
the process of
adding up all
incoming potentials
is called synaptic
integration
Inhibitory
At the end of an action potential,
what happens?
Synaptic Transmission
• Electrical signals are changed into chemical
signals through process called exocytosis
• Exocytosis is a process in which an
intracellular vesicle (membrane bounded
sphere) moves to the plasma membrane and
subsequent fusion of the vesicular
membrane and plasma membrane ensues.
Following an
action potential:
Neurotransmitters
will be released in
the synaptic cleft
and influence the
post-synaptic
neuron…
Need to get
through the
membrane
Exocytosis
The pre-synaptic terminal at rest
Action potential arrives 
Influx of calcium
Different types of
postsynaptic neurotransmitter
receptors
Ionotropic
Metabotropic
Ionotropic:
The receptor binds and performs as a gate for ions
Metabotropic:
The receptor binds and links to G-protein
G-protein coupled receptors
(metabotrophic receptors).
Ionotropic
Fast, but weak
Metabotropic
Slow, but strong
How do drugs influence
synaptic transmission?
Cocaine blocks the NET
A synapse that uses norepinephrine (NE)
Fluoxetine/Prozac blocks the SERT
A synapse that uses serotonin/5-HT
Agonists
• drugs that increase or mimic the effect of a
neurotransmitter
Antagonists
• a drug that decreases or block the effect of a
neurotransmitter