Term
| What are the diff b/t electrical and chemical synapses? |
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Definition
| -Chemical use neurotransmitter, while electrical use gap junctions |
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Term
| How are gap junctions formed? How long is the delay between action potential in the two cells? |
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Definition
-Formed by hexameric subunits called **connexons
-There is only a 0.1ms delay |
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Term
| How does the neurotransmitter vesicle attach to the membrane? What stimulates it's fusion and release? |
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Definition
-A complex called **SNARE forms from *synaptobrevin on the vesicle and *syntaxin & SNAP-25 on the membrane
-This holds the vesicle in place until it is ready for release
-Ca2+ enters and binds to **synaptotagmin on the vesicle to stimulate its fusion with the membrane
For memory;
-The vesicle has both the synapto- proteins
-Ca2+"tags" the vesicle for it to be released
-Also, "Oh snap, the membrane has a syntax error" lol |
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Term
| Give diseases/toxins (3) that effect the presynaptic terminal and their mechanisms? |
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Definition
1. Botulinum toxin; affects the *SNARE protein at *NMJ, inhibiting release of **stimulatory ACh
-Produces **flaccid paralysis (like floppy babies)
2. Tetanus toxin; affects the *SNARE protein at *interneurons of spinal cord, inhibiting release of **inhibitory transmitter
-Produces **tetanic contractions
3. Lambert-Eaton Myasthenic Syndrome (LEMS); autoimmune disease that attacks calcium channels
-Get muscle weakness; more profound that in MG and with less occulomotor involvement |
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Term
| Described the steps in vesicle generation? |
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Definition
-Vesicle starts in a **clathrin coated pit and is associated with *clathrin triskelions (basically scaffolding)
-A *dynamin ring forms and pinches of membrane
-It is translocated by actin and uncoated with the assistance of *Hsc-70 & *auxilin
-Whole process takes about a minute |
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Term
| What are the different responses that a localized increase in Ca2+ and diffuse increase in Ca2+ can produce in the presynaptic neuron? |
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Definition
-Local gives release of *small-molecule neurotransmitter (in clear, small vesicles)
-Diffuse gives release of *both small & large-molecule neurotransmitter (larger, darker vesicles)
-The large proteins also have way faster transport down the axon; small ones use bulk flow of 2-3mm/day, large get about 300mm/day |
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Term
| What are the three classes of signaling molecules? |
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Definition
1. Cell-impermeant; received at surface
2. Cell-permeant; received intracellularly
3. Cell-associated; on surface, received at surface |
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Term
| What are the four classes of cellular receptors? Which function as neurotransmitter receptors? |
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Definition
1. Channel-linked
2. Enzyme-linked
3. G-protein-coupled
4. Intracellular
-The last three are metabotropic, and the first is ionotropic
-Only 1 & 3 receive neurotransmitter |
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Term
| What is the AMPA receptor? |
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Definition
-It is an **ionotropic transmembrane receptor for **glutamate in the CNS that mediates ***fast excitatory synaptic transmission
-Main excitatory signal receptor in the CNS |
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Term
| What is the NMDA receptor? |
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Definition
-Same as AMPA, but is ***slower & longer excitatory
-It is non-selective for cations
-Both are named for synthetic drugs that can bind them, however, this is misleading because both of them naturally bind *glutamate |
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Term
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Definition
-It is basically the reverse of AMPA
-Generates a **fast inhibitory response by allowing entry of *Cl- into the cell
-Main inhibitory receptor of the CNS
-Binds *γ-aminobutyric acid (GABA) |
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Term
| What are the two types of G-proteins? How are they activated |
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Definition
-Can be heterotrimeric with *α, β, and γ subunits
-Or can be monotrimeric and a member of the *Ras family
-Most are hetero
-Both are activated by receiving a phosphate from *GTP |
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Term
Give the G protein and response type for the following;
-Norepinephrine
-Glutamate
-Dopamine |
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Definition
-Norepinephrine; Gs->cAMP->stimulation
-Glutamate; Gq->DAG & IP3->stimulation(ish)
-Dopamine; Gi->lower cAMP->inhibitory |
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Term
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Definition
-Nerve growth factor
-Received at TrkA and can go the three typical ways (PI3K for survival, and Grb2[Ras path] & PLC for nerve outgrowth) |
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