Flashcards in 03b: The Synapse (Pre/Post) Deck (25)
Electrical synapse formed by (X).
X = gap junctions (connexins)
(Chemical/electrical) synapses are directional.
You'd find synaptic delay in (chem/electrical) synapse.
(Chem/electrical) synapses are more amenable to modulation by controlling factors. Why?
Chemical; multiple biochem steps involved
In order to cause muscle response to nerve stimulation, Ca has to be applied where and when?
In immediate vicinity of synaptic region, just before the arrival of AP
T/F: NT release from pre-synaptic terminal can occur without AP if Ca is present intracellularly.
Ca is ideal for role of internal messenger because its (intra/extra)cellular concentration is at such (high/low) values at rest.
T/F: Each MEPP represents response of muscle to single ACh molecule.
False - reponse to quantum of NT
EPP are usually (X) times (smaller/larger) than MEPP.
X = 2-3 (or n) times larger
(X) proteins are implicated in control of exocytosis.
X = SNARE
Tethers vesicles to cytoskeletal structures
Sensese elevation of Ca and triggers formation of fusion pore
Botulinum toxin function
Inhibits transmitter release via proteolysis of SNARE proteins
List three mechanisms of NT removal from synaptic cleft.
1. Degradation by enzymes
2. Diffusion away from cleft
3. Reuptake by transporters (use Na gradient)
List the types of post-synaptic receptors.
T/F: Ionotropic receptor is itself an ionic channel.
T/F: The machinery that converts electrical impulse to chemical signal and back is all confined to synaptic region.
The "reversal potential" at NMJ occurs when (product/sum/difference) of (X) equals (Y). What is the value of this potential?
X = currents of K and Na
Y = 0
NMJ ratio of permeability for ACh-induced current.
Na/K = 1.25
NMJ: At potentials more negative than reversal potential, current is (positive/negative), which means net flow of (X) is directed (inward/outward).
X = positively-charged ions
At NMJ, the reversal potential is more (positive/negative) than resting potential. Thus, response is (de/hyper)-polarization and synapse is (excitatory/inhibitory).
Positive; depolarization; excitatory (EPSP)
By definition, an IPSP response drives the (X) away from (Y) potential.
X = membrane potential;
Y = threshold
T/F: Inhibitory synapse can achieve its effect without evoking visible change in membrane voltage.
True - stabilizes membrane at/near resting potential
Explain the (EPSP/IPSP) provoked by GABA.
Increases Cl-selective conductance, "clamping" membrane potential around E(Cl), which is at the resting potential