4. Synapses and Synaptic Transmission Flashcards
Electrical v Chemical Synapse
Electrical: 6 connexins form connexon in each cell which connect to form gap jcn; rapid, bidirectional
Chemical: neurotransmitter released over a synaptic cleft, interacts with ligand gated channels to produce AP; unidirectional and slower
Steps in chemical neurotransmission (very brief)
AP depolarizes
Ca influx
vesicles fuse and release neurotransmitters
transmitter binds post synaptic receptor
open/close ion channel
postsynaptic membrane potential change(+ or -)
NMJ neurotransmitter and receptor
ACh and nicotinic
Ligand v G-protein Transmission
Ligand is faster bc receptor and channels are part of the same molecular complex
G-protein is slower and acts indirectly with ion channel or thru other effectors
Lambert-Eaton Myasthenic Syndrome!!!!!
small cell paraneoplastic with Abs against L-type Ca channels
Myasthenia Gravis
AI dz that targets nicotinic ACh receptor at NMJ
Botox and Tetanus
Cleave SNARES. If for they ask which one, guess synaptobrevin
- Botox prevents release of ACh
- Tetanus selectively targets GABBAergic (inhibitory) synaptic transmission
Post Synaptic Potentials are ______ potentials?
Graded
EPSP
excitatory, opening channels with permeability to cations, drive membrane potential closer to threshold, increase likelihood of AP
-Ex. Glutamate or Aspartate
IPSP
inhibitory, permeable to anions(Cl) hyperpolarization or shunting of excitatory current; potential away from threshold, decrease likelihood of AP
-GABA(brain), glycine(spinal cord)
Temporal Summation
2 PSPs in same synapse occur at almost same time
Spatial Summation
2 different synapses but very close in location at close time interval
Autonomic dysfunction points you to _________ system
cholinergic
Generalized weakness, no sensory defects after exercising or eating bananas
Periodic Paralysis
-hyperK due to Na channel mutation(gain of fcn)
