The normal concentrations for intracellular and extracellular potassium in a neuron are [K+]in = 150 mM and [K+]out = 5 mM, respectively. Due to an electrolyte imbalance, a patient has the following intracellular and extracellular concentrations of potassium: [K+]in = 140 mM and [K+]out =2 mM. Using the Nernst equation (Chapter 4), calculate the equilibrium potential for potassium in the cells with normal K+ distributions and of the diseased patient. Refer back to Question #1. Will it be easier or more difficult to generate an action potential in the diseased neuron as compared to the normal neuron? Why?

Biochemistry
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ISBN:9781319114671
Author:Lubert Stryer, Jeremy M. Berg, John L. Tymoczko, Gregory J. Gatto Jr.
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The normal concentrations for intracellular and extracellular potassium in a neuron
are [K+]in = 150 mM and [K+]out = 5 mM, respectively. Due to an electrolyte
imbalance, a patient has the following intracellular and extracellular concentrations
of potassium: [K+]in = 140 mM and [K+]out =2 mM. Using the Nernst equation
(Chapter 4), calculate the equilibrium potential for potassium in the cells with
normal K+ distributions and of the diseased patient.
Refer back to Question #1. Will it be easier or more difficult to generate an action
potential in the diseased neuron as compared to the normal neuron? Why?
Transcribed Image Text:The normal concentrations for intracellular and extracellular potassium in a neuron are [K+]in = 150 mM and [K+]out = 5 mM, respectively. Due to an electrolyte imbalance, a patient has the following intracellular and extracellular concentrations of potassium: [K+]in = 140 mM and [K+]out =2 mM. Using the Nernst equation (Chapter 4), calculate the equilibrium potential for potassium in the cells with normal K+ distributions and of the diseased patient. Refer back to Question #1. Will it be easier or more difficult to generate an action potential in the diseased neuron as compared to the normal neuron? Why?
Expert Solution
Step 1

Recall that the Nernst equation for calculating reversal potential is:

Eion  = RT/Zf log [Co]/[Ci

where Eion is the reversal potential, R is the gas constant, T is the absolute temperature in Kelvin Z is the valency of the ion and is Faraday's constant and [Co],[Ci] is ion concentration outside and inside the cell.  

Reversal potential is also knowns as equilibrium potential. Equilibrium potential is the membrane potential required to produce electrochemical equilibrium. 

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