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27 Cards in this Set
- Front
- Back
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What are 2 types of synapses where cells can communicate to eachtother?
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Electrical synapses=gap junctions btwn cells
Chemical synapses=requires neurotransmitters |
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In the adult brain, what type of synapse is most prevalent?
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chemical
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For electrical synapses, what junction forms between cells and how far does the signal propagate?
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gap junction=connexons
Only local communication |
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What steps occur when AP reaches the terminal bouton?
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1. AP causes depolarization which causes Ca++ to rush in through the open Ca++ channels
2. Ca++ causes the vesicles containing the neurotransmitter to fuse to the cell membrane and release the neurotransmitter into the intersynaptic space 3. NT binds to the postsynaptic cleft receptors 4. The NT on the postsynaptic receptors causes ion gates to open or close to evoke and EPSP or IPSP |
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What is an ionotropic receptor?
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ionotropic= cause ion channels to open when neurotransmitter binds to receptor
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A G-protein that activates intracellular signaling that leads to an ion channel opening to effect the excitability of a cell membrane is an example of what kind of neurotransmitter receptor?
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metabotropic
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What classes of receptors does Glutamate utilize?
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AMPA
NMDA Kainate |
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For each of the following receptors, identify if it is a ionotropic or metabotropic receptors:
1- AMPA 2-Kainate 3-GABA b 4-Serotonin 5-Purines 6-Glutamate 7-Dopamine 8-NMDA 9-NE, Epi 10-Histamine 11-Muscarinic |
1-ionotropic
2-ionotropic 3-metabotropic 4-both 5-both 6-metabotropic 7-metabotropic 8-ionotropic 9-metabotropic 10-metabotropic 11-metabotropic |
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What are end plate potentials?
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An increase in membrane potential from spontaneous minis which 1 vesicle of neurotransmitter is released that wasn't caused from an AP or stimulus
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What major proteins are essential for neurotransmitters to be released and what is their role?
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synaptobrevin=binds to vesicle membrane
syntaxin= binds to plasma membrane SNAP-25= binds to plasma membrane synaptotagmin=senses Ca++ levels |
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My face is getting tooooo wrinkly. What does my dermatologist want to inject in my face and what does it do?
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Botulinum toxin= BOTOX: blocks ACh to reduce muscle contraction and relax the face
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Oh no! A toxin cleaved my synaptobrevin AND my synaptotagmin! What toxin did that?
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Clostridial toxins produced from Clostridium bacteria
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How is glutamate synthesize and why is it synthesized?
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Glutamate can't cross the BBB so glutamine from glial cells is converted to glutamate by glutaminase
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When glutamate is released into the synaptic cleft, how does AMPA and NMDA create depolarized the post synaptic membrane?
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AMPA is excitatory and fast activation and desensitation so you need enough glutamate to get a good depolarization. NMDA is slowly excitatory and very permeable to calcium but is blocked by Mg++ unless there is enough glutamate released. The AMPA can sense how much to fire because of NMDA's reaction. Synapses have both receptors so their effects are additive
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What enzyme synthesizes GABA?
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glutamic acid decarboylase (GAD) synthesizes GABA from glutamate
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What is the most common GABAb receptor in the human brain?
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alpha1/beta2/gamma2
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What ion is GABAb receptors permeable to and what does this do to the cell membrane?
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Cl- flows into the cell causing stablization of a negative membrane potential to inhibit firing of signals
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What do barbiturate drugs do?
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enhances GABA receptor so is inhibitory
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What is an autoreceptor and an example of it?
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neuromodulator that acts on the same transmitter presynaptic terminal
ex) norepinephrine blocks Ca++ channels in presynaps |
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How does acetylcholine effect the excitability of a cell when it binds to the mAChR receptors?
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That receptor causes certain K+ channels to open which lowers the resting membrane potential so it can't reach threshold
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What Galpha unit does Norepinephrine activate and what are the downstream effects?
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Gs= activates cAMP --->PKA
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What Galpha unit does glutamate activate and what are the downstream effects?
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Gq=IP3 and DAG-->Ca++levels---->PKC
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What Galpha unit does dopamine activate and what are the downstream effects?
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Gi=inhibits cAMP
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What can reverse the effects of phosphorylation by neuromodulators stimulating intracellular pathways?
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phosphatases (PP1 PP2 PP2B)
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What does the modulating neurotransmitter acetylcholine act on and where is it stored?
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activates both ionotropic and metabotropic receptors
the cell bodies that release Ach in the brain are located in the septal nuclei and the nucleus basalis |
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Name some catecholamines and what kind of receptors do they target
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Epi, NE, dopamine bind to metabotropic receptors that activate or inhibit intracellular pathways
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What are the classes of modulating neurotransmitters?
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ACh
Catacholamines Serotonin Peptide neurotransmitters Unconventential- NO, endogenous cannabinoids |
