Exam 2 - Lecture 24 (Synapse 2) Flashcards
What are the 4 synaptic events that occur?
- APs open VG Ca2+ channels
- NTM release
- NMTs bind to their receptors
- Changes postsynaptic membrane potential
What happens to postsynaptic membrane potential when NTMs bind to their receptors?
it changes
What does each synaptic site generate?
postsynaptic membrane potentials
What 5 things happen after an excitatory synapse?
- Excitatory NTMs are released (ACh or glutamate)
- ACh and Glutamate bind to AChR and GluR
- Rs open ligand-gated ion channels for Na+
- Na+ influx into postsyn. membrane
- Generates depolarizing EPSP
What 5 things things after an inhibitory synapse?
- Inhibitory NTMs are released (glycine or GABA)
- Glycine and GABA bind to GlyR or GABA receptor
- Rs open ligand-gated Cl- channels
- Cl- influx
- Generates hyperpolarizing IPSP
What happens when excitatory and inhibitory synapses act at the same time?
They cancel each other out
Where do graded potentials travel?
To the axon hillock
What is present at the axon hillock and axon?
VG Na+ and K+ channels
When does the axon hillock generate APs?
When the sum of EPSPs and IPSPs goes over threshold membrane potential
Why are EPSPs and IPSPs referred to as graded potentials?
Because they vary in size as opposed to being all or none
What is spatial summation?
Summation of multiple separate signals arriving at different synaptic sites simultaneously (A+B; A+B+C)
What is temporal summation?
Summation of multiple signals arriving at a single synaptic site (AA; BBB; CCCC)
Where does the summed graded potential have to go over threshold voltage for an AP to occur?
at the axon hillock
What is the role of EPSPs and IPSPs in tetanus?
EPSPs are present with no IPSPs so neurons are constantly firing.
