Term
| Which is more common, electrical or chemical transmission? |
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Definition
| Chemical. Also, electrical is not limited to nervous system. |
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Term
| Chemical Neurotransmission |
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Definition
| Neurons are seperated by a cleft. |
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Term
| Distances between cell membranes of electrical/chemical synapses |
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Definition
Electrical - 3.5 nm (usually 20)
Chemical 20-40nm No direct connection. Vessicles, active zone. Postsynaptic receptor. |
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Term
| Are chemical and electrical channels uni or bidirectional? |
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Definition
Electrical - usually bidirectional
chemical - unidirectional |
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Term
| Four criteria of a neurotransmitter |
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Definition
Must by synthesized by the presynaptic neuron.
Must be present in presynaptic terminal and released in amounts sufficient to exert an action on the postsynaptic terminal
When applied exogenously, it mimics the action of the endogenously released transmitter, activating the same ion channels or 2nd messengers
A specific mechanism exists for removing it from its site of action (usually the synaptic cleft). |
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Term
| Where does neurotransmitter synthesis occur? |
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Definition
| In the cell body or at the axon terminal. Stored in synaptic vessicles. Can be more than one type per axon. |
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Term
| What causes release of neurotransmitter from the synaptic cleft? |
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Definition
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Term
| What three ways can a neurotransmitter be inactivated? |
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Definition
| Degraded by extracellular enzymes, diffuse into the extracellular space, orbe taken back up into the presynaptic terminal and repackaged. |
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Term
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Definition
| Along with Ca2+, controls the docking and function of synaptic vesicles. It is a low-molecular-weight GTP binding protein. |
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Term
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Definition
Rab3A targets vesicles to their release sites. Complexed to GTP it binds synaptic vesicles. When Rab3A hydrolyzes its bound GTP to GDP, it prevents vesicles from leaving the active zone.
DURING FUSION AND EXOCYTOSIS: Rab3A-GDP dissociates from the vesicle. There is then an exchange of GTP for GDP. This Rab3A GTP then binds a new synaptic vesicle. |
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Term
| What mediates the interactions between the synaptic vesicle and the cytoskeletal elements of the nerve terminal? |
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Definition
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Term
| What trafficks target vesicles to active zones? |
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Definition
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Term
| What docks vesicles at active zones and primes them for release? |
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Definition
Vesicle proteins and corresponding nerve terminal proteins.
VAMPs to (SNAP-25 and syntaxin). Also, synaptotagmin to syntaxin and neurexin. |
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Term
| What modulates release of a neurotransmitter? |
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Definition
| Synaptophysin is a intergral membrane protein in synaptic vessels is phosphorylated by tyrosine kinases and may regulate release. |
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Term
| Direct gating of ion channels is mediated by what? |
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Definition
| Ionotropic receptors. Sometimes called ligand-gated. Usually five subunits, each with four transmembrane alpha helices. |
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Term
| What is indirect gating mediated by? |
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Definition
| Metabotropic receptors. Distinct from ion channel it regulates. |
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Term
| Examples of neurotransmitter receptors |
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Definition
| ACh, GABA, Glycine, AMPA, NMDA |
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Term
| Examples of secondary messenger receptors |
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Definition
| alpha and beta adrenergic, serotonin, dopa, muscarinic ACh receptors and receptors for neuropeptides. |
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Term
| What are the four second messenger pathways? |
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Definition
| cAMP cascade, Inositol Polyphosphate pathway, diacylglycerol, arachidonic acid. |
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Term
| Arachadonic acid is metabolized to? |
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Definition
| Mainly eicosanoids. Prostaglandins and thromboxanes by cyclooxygenase and leukotriense also. |
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