Synaptic Physiology II Flashcards
What strain of botulinum is the most common in the US?
type A
In the heart, parasympathetic neurons release _____ onto the pacemaker cells.
ACh
How does botulinum work?
it prevents the release of ACh across the synaptic cleft (pre-synaptic)
This is a protein that helps the Ca++ fuse the vesicle membranes.
synaptotagmin
What does botulinum neurotoxin predominantly affect?
the PNS nerve endings
How can a synapse be silent?
it doesn’t contain AMPA receptors (yet)
What is the NT for the NMDA receptor?
glutamate
In the heart, cAMP stimulates ____, which phosphorylates ____, allowing them to open.
PKA; Ca++ channels
_____ binds to presynaptic stimulatory nerve terminals and blocks the release of ACh.
Botulnum toxin
What is a silent synapse?
an excitatory pre-synaptic synapse that does not evoke any change upon firing to the post-synaptic cell
How can a pre-synaptic cell be strengthened by NMDA receptor activation?
the entry of Ca++ ions into the postsynaptic dendrite releases NO gas that diffuses back across the synapse to potentiate NT release
What tissue does tetanospasmin target?
nervous tissue
What is an AMPA receptor?
a postsynaptic glutamate receptor that is very similar to the ACh receptor
Where does tetanospasmin initially bind?
to peripheral nerve terminals
Synapses in the CNS can be selectively strengthened by the _____.
NMDA receptor
What are SNARE proteins?
proteins that teather two membranous structures together (ie synaptic vesicles)
What is tetanospasmin? Where is it encoded?
the tetanus toxin; on a plasmid
What proteins does tetanospasmin cleave?
synaptobrevin II
Where are electrical synapses important?
in the heart and smooth muscle; embryonic cells
What is synaptobrevin?
the v-snare protein
This prevents the release of ACh across the synaptic cleft (pre-synaptic).
botulinum toxin
What is the v-snare? What proteins makes it?
the vesicle snare; synaptobrevin, syntaxin, and SNAP-25
Increased K+ _____ the membrane.
hyperpolarizes
Odorants in the air are _____ for receptors found on the surface of 1a sensory neurons.
ligands
___ is the ligand for the opening of Ca++ channels in the heart muscle and neurons.
NE
How do silent synapses become normal again?
by activating NMDA receptors, which inserts AMPA receptors into the postsynaptic membrane –> normal response
In the heart, ACh binds to ______ receptors on the pacemaker cells, resulting in the opening of a K+ channel.
muscarinic
Synapses in the ___ can be selectively strengthened by the NMDA receptor.
CNS
How does tetanospasmin work?
it blocks the release of inhibitory NTs across the synaptic cleft
Botulnum toxin binds to ________ and blocks the release of _____.
presynaptic stimulatory nerve terminals; ACh
These are proteins that teather two membranous structures together (ie synaptic vesicles).
SNARE proteins
What is an NMDA receptor?
an excitatory synapse for glutamate that is plugged by a Mg++ ion and is highly permeable to Ca++ ions
What do gap junctions contain?
specialized protein pores (connexons) that bridge the gap btw the cells to connect their cytoplasms
This is the name for the tetanus toxin.
tetanospasmin
NE is the ligand for the opening of Ca++ in the _____ and ____.
heart muscle and neurons
____ is the causative agent of tetanus.
Clostridium tetani
What is synaptotagmin?
a protein that helps the Ca++ fuse the vesicle membranes
In olfaction, the activated G-proteins will activate _____ to synthesize the second messenger, ____.
adenylyl cyclase; cAMP
What is associative plasticity?
become potentiated on their own AND when combined with signals from post-synaptic celss
What is the 1a symptom of botulism?
flaccid paralysis/weakness
What triggers fusion of the SNARE proteins?
Ca++
The clostridia toxins include ____ and _____.
tetanus toxin; botulinum neurotoxin
An Mg++ ion plugs which kind of receptor?
an NMDA receptor
What is syntaxin?
a v-snare protein
What do the post-synaptic cells secrete, after Ca++ influxes into the cell?
additional AMPA receptors to increase the size of the glutamate-induced synaptic potentials
Where are silent synapses especially prevalent? Why?
the developing brain; to verify appropriate synapse formation
These are specialized protein pores (connexons) that bridge the gap btw the cells to connect their cytoplasms.
gap junctions
This is an excitatory synapse for glutamate that is plugged by a Mg++ ion and is highly permeable to Ca++ ions.
an NMDA receptor
When an odorant binds to its receptor, _____ is initiated.
a G-protein cascade
What toxin prefers the PNS nerve endings?
botulinum
Tetanus and botulism result from deadly toxins that are actually _____ that selectively cut SNARE proteins, thereby blocking exocytosis.
proteases
What is SNAP-25?
a v-snare protein
What opens the gate in an NMDA receptor? What removes the Mg++ ion?
synaptic activation; a post-synaptic AP
What is the key to neuronal associative learning and makes CNS synapses smart?
the NMDA receptor
In the heart, ACh binds to muscarinic receptors on the pacemaker cells, resulting in ______.
the opening of a K+ channel
NE is the ligand for the opening of _____ in the heart muscle and neurons.
Ca++ channels
Electrical current can spread from one neuron to another where there are _____.
gap junctions
This is a postsynaptic glutamate receptor that is very similar to the ACh receptor.
an AMPA receptor
