General Properties of Synaptic Transmission Flashcards
Electrical synapses
Fusion of the pre and post synaptic buttons
Conduct through gap junctions without synaptic delay
Connected by connexons
Can be bidirectional
Chemical synapse
Unidirectional with a small delay
No cytoplasmic continuity
Most prevalent ype in CNS
NT rules
Synthesized and stored by neurons Released by presynaptic terminal (Ca dep) Diffuse across cleft Interact with post receptor Activate physiological process Terminated
Mech of NT release
AP reaches terminal Opening of V gated Ca channels Ca enters Ca binds to synaptotagim SNARE proteins induce vesicle formation to membrane NTs emptied into synaptic cleft
Activation of post neuron
NTs diffuse and pind to Ionotropic or metabotropic receptors
Postsynpatic potential that results in depolarization or hyperpolarization
Removal of NTs
Terminal reuptake
Glial uptake
Enzymes
Diffuse away
Ion channels in post membrane return to resting state
Ionotropic characteristics
Receptor attached to channel directly
Rapid
Used by glutamate, GABA, and glycine
Metabotropic charactersitcis
Delay in ooening but open for longer
CNS, PNS
CNS - GABA and glutamate
PNS - Ach and Norep
Excitatory signals
Nonselective cation channels
AMPA - Na and K
NMDA - Na/K/Ca
Non-NMDA receptors
AMPA - 4 subunits
Ka - slower than AMPA
NMDA receptors
Bind to Mg when hyperpolarized, depolarization releases the Mg and allows passage
More open to Ca.
Ketamine and PCP block this
Inhibitory chemical synapses
Opens Cl or K channels
Cl enters to increase negative charge (also shunting inhibition)
K leaves to make closer to potassium equilibrium potential
GABA postive and negative modulators
Pos - benzodiazepines (need GABA), ehtanol, barbituates (don’t need GABA), steroids increase open time
Neg - picrotoxin blocks channel, gabzine nblocks receptor, bicucullin blocks receptor
Presynaptic mechs of modulating synaptic strenght
Increase/decrease degradation Increase/decrease release Block NT release (botulinim) Inhibt NT synthesis Reduce NT reuptake or degrdation (MAO inhibt, AChE inhibit, SSRI)
