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17 Cards in this Set
- Front
- Back
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What is the process of an excitatory postsynatpic response?
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Opening of cation-selective channel
--> excitatory current (EPSC) --> depolarizing excitatory potential (EPSP) |
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What is the process of an inhibitory response?
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Opening of Cl-selective GABA channels or K-selective ion channels
--> inhibitory current (IPSC) --> Inhibitory potential (IPSP) |
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What determines the firing probability of an individual neuron?
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Simultaneous excitatory and inhibitory inputs
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What type of potentials are always found at the NMJ?
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Always excitatory
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What are ionotropic receptors?
What is the structure? |
Ligand-gated ion channels that mediate fast changes in postsynaptic (5-30 ms) excitability
Made up of 5 subunits around pore |
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What makes an ionotropic receptor excitatory vs. inhibitory?
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Excitatory: cation selective
Inhibitory: Cl-selective (GABA and glycine receptors) |
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What do metabotropic receptors do?
How are they formed? |
Mediate slow changes in postsynaptic excitability (hundreds of ms)
Formed from single seven-transmembrane domain polypeptides coupled to G-proteins |
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What are the steps for metabotropic receptor activation? (4)
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1. NT binds receptor
2. GTP binds to receptor, beta and gamma subunits leave 3. Ga activates effector protein 4. Intermediate steps --> open or close ion channels |
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What is the nicotinic Ach receptor?
What does it mediate? |
Ligand-gated ion channel at the NMJ
Mediates fast synaptic transmission |
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What does the snake toxin alpha-bungarotoxin do?
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Bind to and blocks nicotinic ACHR --> muscle paralysis
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What is the process of nicotinic ACHR activity?
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Ach binds --> increases open potential of receptors (for msecs)--> individual channels let cations in --> summation of channels leads to EPSC --> depolarization --> AP
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How does Erev determine whether a channel is excitatory or inhibitory?
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Erev < threshold = inhibitory
Erev > threshold = excitatory |
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What happens to Erev when...
a. [Na]ec decreases b. [K]ec increases |
a. Erev gets more negative
b. Erev gets more positive |
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What is the permeability of nAchR to K and Na?
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Equal permeabilities
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When is PSP depolarizing?
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Erev > Vmem
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When is PSP hyperpolarizing?
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Erev < Vmem
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What drives the current at negative potentials?
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Na in --> depolarizing
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