1. Effects of Excitatory and Inhibitory Potentials on Action Potentials

2. Overview of A Neuron Found in brain, spinal cord and nervous system
Electrically excitable
Communicate via electrical and chemical synapses
Made up of a soma (cell body), dendritic tree and an axon

3. Axon Properties Where action potential is propagated
Contains voltage gated sodium and potassium channels
Resting membrane potential: ~ -65 mV

4. Action Potential
Occurs when membrane potential exceeds the threshold potential
Occurs when Na+ channels are activated (inflow of Na+)
Causes positive slope of action potential
K+ channels open slightly later (outflow of K+)
Causes downward slope of action potential

5. Transmission of Action Potential Across Synapse
Pre-synaptic cell action potential releases Ca2+ in the axon terminal
Axon terminal releases vesicles filled with neurotransmitters
Inhibit or help create an action potential
Excitatory Neurotransmitters:
Acetylcholine
glutamate
Inhibitory Neurotransmitters:
GABA
glycine

6. Post Synaptic Potentials
Inhibitory Post Synaptic Potentials (IPSP)
Decreases the potential of the membrane
Increases permeability of K+
K+ flows out of cell
Decreases the chances of an action potential
Excitatory Post Synaptic Potentials (EPSP)
Creates positive synaptic potential
Positive charged ions flow in
Allows Na+ into cell
Easier for Action Potential to fire

7. Ways to Achieve Action Potential
Temporal Summation
One neuron acting on another
Potential starts before the previous one ends
Amplitudes of potentials summate to create larger potential
Spatial Summation
Multiple cells provide input
Input is received in different areas
Input is summated to create a larger potential

8. Observations
Increasing the intensity does not increase the size of the action potential
Action potential is “all or none” response
Potentials can summate to elicit or inhibit an action potential
Must reach a specific threshold potential to create and action potential that will be propagated

9. Conclusion
Many different ways to elicit an action potential or to inhibit one
Temporal and Spatial Summation allow for greater complexity in neural networks
This allows for greater complexity in organisms
neuron can communicate with multiple neurons > greater efficiency.