CN2010 Membrane Physiology Problem 3 Key

CN2010 Membrane - D Comment briefly on the similarities and differences in the response to somatostatin in the three types of animals we have

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Problem 3 KEY Cell equivalent circuits These are the values used in the problem Parameter Units Young Senescent Hibernating C M x10 -10 F 1.0 * 1.0 1.0 V R x10 -3 V -60 -60 -60 g R x10 -9 S 3.0 3.0 12.0 τ R (calculated) x10 -3 sec 33.3 33.3 8.3 * V A x10 -3 V 15.0 15.0 15.0 g A x10 -9 S 20 * 3 20 V +A (calculated) x10 -3 V 5.2 -22.5 * -13 * τ +A (calculated) x10 -3 sec 4.3 16.7 * 3.1 * notes values provided in problem * to be calculated A1. What is the membrane capacitance (C M )? τ R = R M C M , so C M = 0.0333 sec x 3 x 10 -9 S = 1 x 10 -10 F. A2. What is the conductance of the activatable conductance (g A )? V +A = (g R V R + g A V A ) / (g R + g A ) so g A / g R = (V R - V +A )/(V +A - V A ) = 6.5, so g A = 1.95 x 10 -8 S. A3. What is C M ? C M = 1 x 10 -10 F. Unchanged B1. What is V +A ? V +A = (g R x V R + g A x V A ) g A / (g R + g A ) = -23 mV. B2. What is τ +A ? τ +A = C M / g +A = .017 sec (17 msec) C1. What is τ R ? τ R = C M / g R = .008 sec (8 msec) C2. What is V +A ? V +A = (g R x V R + g A x V A ) g A / (g R + g A ) = -13 mV. C3. What is τ +A ? τ +A = C M / g +A = .003 sec (3 msec)
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Unformatted text preview: D. Comment briefly on the similarities and differences in the response to somatostatin in the three types of animals we have examined (e.g. time course, amplitude). The response in both the hibernating and senescent animals is reduced in amplitude compared to awake, young adult animals, to a greater extent in the senescent animals. Comparing to the awake, young adult animals the response is much slower in senescent animals but a little faster in hibernating animals. Overall, at early times after application of somatostatin the response in the senescent animals will be much smaller than the response in either awake or hibernating young animals. The hibernating animal has a smaller overall response....
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This note was uploaded on 02/27/2012 for the course BIO 5571 taught by Professor P.taghert during the Fall '11 term at Washington University in St. Louis.

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CN2010 Membrane - D Comment briefly on the similarities and differences in the response to somatostatin in the three types of animals we have

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