Nuerotransmitters & Synaptic Transmission I Flashcards
How do some neurons and astrocytes communicate
Gap junctions formed by connexons
What do presynaptic receptors regulate
Exocytosis
What chemical synapses are commonly excitatory but proximal contacts often inhibitory
Axodendritic
What chemical synapses are commonly inhibitory and diminishes magnitude of action potentials
Axoaxonic
What chemical synapses are commonly inhibitory
Axosomatic
Which chemical synapse allows astrocytes to take up glutamate released by neurons and metabolize it to glutamine which is then returned back to neuron to be converted back to glutamate
Tripartite synapses
Which amino acids are neurotransmitters
Homocysteine Aspartate GABA Glycine Glutamate
Which gases are neurotransmitters
NO
CO
How are low molecular weight neurotransmitters synthesized
Loaded into small vesicles in the cytosol
How is Nitric Oxide (NO) synthesized
Calcium enters and forms calcium-calmodulin complex
Nitric Oxide Synthase activated
L-arginine converted to L-citrulline and NO
How are high molecular neurotransmitters synthesized
Propeptides loaded into large vesicles with cleaving enzymes
Stored farther from release sites than small vesicles
Energy-driven pump loads vesicles with what
Hydrogen ions
What tethers vesicles to cytoskeleton
Synapsin
What liberates vesicles
Calcium-calmodulin-dependent protein kinase
What facilitates movement of vesicles toward active zones
Rab protein
Which snare proteins are on the vesicle membrane
V-snare
Which snare proteins are on the nerve membrane
T-snare
V-snare synaptobrevin binds to which T-snare
Syntaxin
V-snare synaptotagmin binds to which T-snare
Neurexin
What forms fusion pore to release nuerotransmitters
Synaptophysin
What liberates vesicles by promoting phosphorylation of synapsin and promotes opening of fusion pore
Synapsin
How are small vesicles recycled
Endosomes
How are large vesicles retrieved
Retrograde (dyenin) transport
Ligands influence G-protein altering metabolism and gene expression
Metabotropic
How is ACH synthesized
From choline and acetylcoenzyme-A in presence of choline acetyltransferase
What neurotransmitter do lower motor neurons release
Acetylcholine
Ionotropic, peripheral and central
Nicotinic receptors
Metabotropic, 5 types, excitatory or inhibitory
Muscarinic receptors
Excitatory neurotransmitter throughout CNS
Glutamate
AMPA/Quisqualate and Kainate
Ionotropic
Na+ and K+ flow, NO Ca2+ flow
Agonists open a central pore, provided that glycine also occupies strychnine-insensitive binding site
NMDA
Depolarization extrudes Mg2+ but allows influx of Ca2+ and Na+ and efflux of K+
Non-NMDA receptor mediated
Metabotropic Glutamate receptors
1 & 5: postsynaptic and excitatory
2 & 3: presynaptic and inhibitory
4 & 6-8: presynaptic and inhibitory
Negative feedback suppresses release
Autoreceptors
Inhibitory nuerotransmitter throughout the CNS
GABA
Ionotropic chloride-passing receptor and allosteric binding sites for benzodiazepines and barbiturates
GABA(A)
Second messenger system suppresses Ca2+ channels and enhances K+ channels
GABA(B)
What drug augments GABA-mediated chloride currents reducing anxiety (anxiolytics)
Benzodiazepines
What enzyme converts serine to glycine
Transhydroxymethylase
Inhibitory neurotransmitter in the spinal cord, lower brain stem, and retina
Glycine
Structurally and functionally similar to GABA(A) receptor, ionotropic chloride-passing
Glycine
Which neurotransmitter receptor on motor neurons is blocked by strychnine
Glycine
What blocks release of Glycine
Tetanus Toxin
Which neurotransmitter is excitatory and inhibitory depending on synapse and causes feeling of happiness
Dopamine
All dopamine receptors are metabotropic
D1-like (D1 and D5): excitatory, couple to cAMP
D2-like (D2-4): inhibitory, couple to cAMP
Which neurotransmitter is excitatory and inhibitory depending on synapse and modulates sleep and wakefulness, attention, feeding, and emotional behaviors
Norepinephrine
All norepinephrine receptors are metabotropic
Alpha1 and Beta1: excitatory
Alpha2 and Beta2: inhibitory
Which neurotransmitter is excitatory and inhibitory depending on synapse and inhibits pain sensation
Serotonin
All (but one) serotonin receptors are metabotropic
5-HT1 and 5-HT5: inhibitory
5-HT2: excitatory
5-HT4, 5-HT6, and 5-HT7: excitatory
5-HT3: excitatory (IONOTROPIC)
Inhibitory at most synapses in the medulla and spinal cord (pain sensation)
Enkephalins
Excitatory and inhibitory depending on the synapse; widely throughout CNS (pain sensation)
Substance P
What is inhibited indirectly by 5-HT and Norepinephrine (although they excite enkephalinergic neurons)
Substance P
