L5: Synaptic transmission I - General features Flashcards
What are two types of synapses? Compare and contrast their properties and function
Electrical synapse = ions through gap junctions, fast
Chemical synapses = slower because rely on neurotransmitters released and are dynamic, strength can be modified, can die
What are the 3 types of neurotransmission?
- classical: small-molecule and neurotransmitters
- neuropeptides: can do more to modify transmission than binding to receptor
- gaseous: e.g. NO → we make but cannot store
Describe the 2 different types of vesicle fusion.
classical/full fusion
- membranes merge ( full fusion of vesicle) and contents leaked out into cleft
kiss and run- partial fusion
- vesicle only merges partially to release neurotransmitter, then is reformed and recycled
Describe the sequence of events in classical chemical neurotransmission.
AP → Ca2+ → vesicle fusion → neurotransmitter released (kiss & run) → diffusion within synaptic cleft → binds to receptor → Na+ in → depolarisation → K+ out or Cl- in → repolarisation → neurotransmitter reuptake → vesicle recycled and refilled
What is the difference between spatial and temporal summation?
temporal summation = 2 excitatory events close in time; spatial summation = 2 excitatory events close in space (and time)
what is facilitation?
facilitation = fast-arriving APs cause increased signal and allows modulation of response (i.e. strength of muscle contraction)
Where do we see an example of facilitation within a single synapse?
NMJ -> fast arriving APs = signal increases for every subsequent AP to arrive
- each AP causes increase in (muscle) strength
- modulation within each synapse → changes in magnitude of response
what leads to long-term potentiation
pathway leads to more receptors inserted ⇒ stronger synapse (basis of memory)
what leads to long-term depression
long term depression = same signal for long-term potentiation but receptors removed → bond is not strengthened
