The document outlines key concepts about synapses and neurotransmission. It discusses how action potentials reach the axon terminal and trigger the release of neurotransmitters from synaptic vesicles into the synaptic cleft. It describes the three main types of synaptic connections and the two main types of receptors: ionotropic receptors which open ion channels and metabotropic receptors which activate second messenger systems. Finally, it explains how neurotransmitters can have excitatory or inhibitory effects on the postsynaptic neuron through EPSPs and IPSPs, and how temporal and spatial summation of these potentials can trigger action potentials.

1. Synapse

2. Outline
 Review the Action Potential
 What happens when the action potential reaches the
axon terminal?
 Synaptic Connections
 Neurotransmission
 Types of Receptors
 Ionotropic vs. Metabotropic
 Excitation vs. Inhibition
 Temporal vs. Spatial Summation
 Neurotransmitters

3. Action Potential Demonstration

5. 3 Types of Synaptic Connections Between
Neurons

6. Neurotransmission at the Synapse

7. Lifecycle of Synaptic Vesicle

8. Two Types of Receptors
Ionotropic Metabotropic
 Channel opens in
response to ion binding
 Contains 4-5 subunits that
make up the receptor
structure
 Fast speed of action
• Channel opens in
response to second
messengers
• Contains 1 subunit that
makes up the receptor
structure
• Slow speed of action

9. Ionotropic Receptor

10. Metabotropic Receptor

11. Second Messenger Systems
 Downstream
effects through a
series of
enzymatic
reactions
 Nitric oxide

12. Receptors can have an excitatory or
inhibitory effect.
Excitatory Postsynaptic
Potential (EPSP)
Inhibitory Postsynaptic
Potential (IPSP)
 Promotes excitation of
the postsynaptic
membrane
 Graded potential that
decays over time and
space
 Cumulative effect of EPSPs
are the basis for temporal
and spatial summation
 Temporary
hyperpolarization of a
membrane- prevent action
potentials
 How?

13. Summation
Temporal Summation Spatial Summation
 Many stimuli in a close
span of time
 Repeated stimuli can have
a cumulative effect and
can produce a nerve
impulse when a single
stimuli is too weak
 Many neurons firing
simultaneously in the
same location
 Synaptic input from
several locations can have
a cumulative effect and
trigger a nerve impulse

15. Temporal Summation

16. Excitation or Inhibition of a Muscle

17. Long Term Potentiation (LTP)
 Creating new or stronger synapses
 Occurs by repeated stimulation, an increase in dendritic
receptors, an increase in neurotransmitters
 New synapses can be formed in the olfactory system and
in the hippocampus

18. Review of the Synapse

19. Neurotransmitters
Small Molecule Large Molecule
 Glutamate
 GABA
 Dopamine
 Norepinephrine
 Serotonin
 Acetylcholine
 Neuropeptides
 Lipids
 Gases