please i need the answers for all parts since i have incompleted ones The follow

ID: 83853 • Letter: P

Question

please i need the answers for all parts since i have incompleted ones

The following concentration values (in mM) have been calculated for an example cell shown below: Calculate the equilibrium potentials for each of three ions, assume RT/F = 58 mV INLUDING the 2.3 constant! (round up your answers to the nearest whole number) Consider a neuron that initially has: a resting membrane potential of -20 mV (as established by Na^+/K^+ ATPase) no voltage- or ligand-gated channels initially, no leak channels What will be the effect on the membrane potential of adding leak Na^+ channels to this cell? Considering the reversal potential of Sodium, determine the electrical gradient, the concentration gradient, and net ion flow (IN, OUT, or NONE) for each of the membrane potential below:

Explanation / Answer

The formula to calculate equilibrium potential for an ion is------

Ex= RT/ZxF Ln([X]0/[X]i)

Where,

Ex = Nernst potential for ion X

[X]o = Concentration of X outside the cell

[X]i = Concentration of X inside the cell

zx = Valence of ion X

R = Gas constant

T = Absolute temperature

F = Faraday's constant

Thus according to problem, RT/ZxF=58mV

Then, ENa = 58 Log10(127/8) = 69.6 or 70 mV.

Then, Ek = 58 Log10(6/117) = -74.8 or -75 mV.

Then, ENa = -58 Log10(95/6) = -69.5 or -70 mV.

Na+ leaks means flow of Na+ ions from outside to inside the cell following the conc gradient of Na+ ions. Na+ leaks decrease the – potential inside the cell. If only Na+ leak channels added to the cell then at some point of time it produces action potentials because in normal case Na and K both are leak simultaneously in opposite direction, thus maintain the –potential inside cell. But only increase in leaking Na+ decrease the –potential inside cell.

Electrical gradient

Conc. gradient

Net ion flow

100 mV

70 mV

20 mV

out

0 mV

out

-20 mV

out

-70 mV

none

None

-100 mV

out