Week2 - Email: [email protected] 2. What would happen...

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BIPN 100 TA: Earth Hasassri Section: Tuesday, 8-8:50AM, WLH 2206 O.H.: Thursday, 6-7PM, Espresso Roma Email: [email protected] Week 2 Handout 1. You suspect that a neuron you ordered from eBay doesn’t work properly, but before you decide to return it you measure the membrane potentials. The following ion concentrations exist at 37ºC (assume no other ions contribute to the membrane potential). The V rest was at -75 mV and the threshold potential was at –50 mV. Inside Outside Na + 14 mM 145 mM K + 165 mM 4 mM Cl 5 mM 60 mM a. Determine the equilibrium potentials for Na + , K + , and Cl . b. Assuming that Na + , K + , and Cl all have the same permeability, what is the membrane potential at physiologic concentrations using only these 3 ions? c. How does Part (b) compare with normal resting membrane potential? d. What is the driving force for each ion?
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BIPN 100 TA: Earth Hasassri Section: Tuesday, 8-8:50AM, WLH 2206 O.H.: Thursday, 6-7PM, Espresso Roma
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Unformatted text preview: Email: [email protected] 2. What would happen to an action potential under the following conditions: a. Increase the strength of the stimulus b. If a second stimulus was given during the peak of the action potential c. If a second stimulus of the same magnitude was given during the hyperpolarizing period of the action potential 3. Tetrodotoxin (TTX) was isolated from a puffer fish and administered to a neuron. a. What would happen to the action potential when a stimulus is given after administration of TTX? b. If you eat a puffer fish, would you die? Why or why not? 4. An action potential can reach peak amplitudes up to +50 mV. a. Why doesn’t the depolarization stop at 0 mV? b. What ion currents are responsible for depolarization? Repolarization? Hyperpolarization? 5. During which parts of the action potential does V m nearly reach E Na and E K ? Why does it only nearly reach these potentials?...
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This note was uploaded on 03/10/2011 for the course BIPN 100 taught by Professor French during the Winter '07 term at UCSD.

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Week2 - Email: [email protected] 2. What would happen...

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