Fundamentals of Biological Psychology University of Montana Professor Stuart Hall
Terms in this set (25)
Types of Postsynaptic Potentials (PSP)
- Excitatory (EPSP)
- Inhibitory (IPSP)
Excitatory Postsynaptic Potential
Depolarization of Postsynaptic Membrane.
Cell is moved towards firing an Action Potential.
Occurs when ion channels allow negatively charged ions to move out, and positively charged ions to move in.
Inhibitory Postsynaptic Potential
Hyperpolarization of Postsynaptic Membrane.
Cell is moved farther away from firing an Action Potential.
Occurs when more negatively charged ions are added to an already negatively charged receptor cell.
After an Action Potential has traveled down an axon, a neurotransmitter gets released, affecting whether that postsynaptic cell is more or less positive.
EPSP & IPSP
- They both travel from the site of generation
- Travel as a graded potential (aka cable properties)
This is where the EPSP and IPSP are summed.
There are different ways that they can be added up, to determine if the Threshold has been reached or not.
EPSP/IPSP Summation Types
Multiple EPSP and IPSP from different locations fire in such a way that they all converge at the Axon Hillock at the exact same time, so that they all have an influence there
The EPSP and IPSP arrive at the Axon Hillock close enough together in time (though not at the exact same time) so that they can be added to each other.
They build upon each other to eventually reach Threshold.
Absolute Refractory Period
What happens when Na+ channels are activated?
Chemical Events at the Synapse
The major sequence of events allowing communication between neurons across the synapse
1st Chemical Event at the Synapse
Neuron synthesizes chemical that serve as neurotransmitters
2nd Chemical Event at the Synapse
Neurons store neurotransmitters in axon terminals or transport them there
3rd Chemical Event at the Synapse
An action potential triggers the release of neurotransmitters into the Synaptic Cleft
4th Chemical Event at the Synapse
The neurotransmitters travel across the Synaptic Cleft and attach to a receptor on the Postsynaptic Membrane of the receiving neuron
5th Chemical Event at the Synapse
The neurotransmitters separate from the receptors
- This process should be controlled and time-limited
6th Chemical Event at the Synapse
The neurotransmitters are taken back into the Presynaptic Neuron, diffuse away, or are inactivated by chemicals
- This is most commonly what happens
- Called "re-uptake"
7th Chemical Event at the Synapse
The postsynaptic cell may send negative feedback to slow the release of further neurotransmitters
- This happens less commonly
- Purpose is to prevent too much neurotransmitter from being sent to the postsynaptic cell
A type of neurotransmitter effect where the receptor activates immediately and opens up almost any ion channel
- "Very straightforward"
A type of neurotransmitter effect where multistep process leads to a change in the postsynaptic cell being either depolarized or hyper polarized
- "Multiple steps"
Modulation of Neurotransmitter Release
- Presynaptic Receptor
- Axoaxonic Synapse
- Postsynaptic Inhibition
Sensitive to it's own neurotransmitter
The postsynaptic cell says feedback saying "that's too much, knock it off."
Sensitive to a different neurotransmitter
Inhibition or Facilitation
A different type of neurotransmitter is being released, and inhibiting or augmenting the presynaptic cell's activity
The neuron releases chemicals that travel back to the presynaptic terminal and modulate the amount of it's own neurotransmitters being released.