Ion Concentrations and Equilibrium Potentials

Vocabulary flashcards covering intracellular/extracellular ion concentrations and equilibrium potentials for squid giant axon and mammalian neurons based on the provided table.

the specific electrical voltage across a cell membrane that exactly balances the chemical concentration gradient of a particular ion, resulting in no net movement of that ion.

Equilibrium potential

Squid Giant Axon $Na^+$ intracellular concentration

50 mM

Squid Giant Axon $Na^+$ extracellular concentration

440 mM

Squid Giant Axon $Na^+$ equilibrium potential

+55 mV

Squid giant axon K⁺ intracellular concentration

400 mM

Squid giant axon K⁺ extracellular concentration

20 mM

Squid giant axon K⁺ equilibrium potential

-76 mV

Squid giant axon Cl^- intracellular concentration

40 mM

Squid giant axon Cl^- Extracellular concentration

560 mM

Squid Giant Axon Cl^- Equilibrium potential

-66 mV

Squid Giant Axon Ca²⁺ Equilibrium potential

145 mV

Squid giant axon Ca²⁺ intracellular concentration

0.4 uM

Squid giant axon Ca²⁺ extracellular concentration

10 mM

mammalian neuron Na⁺ intracellular concentration

18 mM

mammalian neuron K⁺ intracellular concentration

140 mM

mammalian neuron Cl^- intracellular concentration

7 mM

mammalian neuron Ca²⁺ intracellular concentration

100 nM

mammalian neuron Na⁺ extracellular concentration

145 mM

mammalian neuron K⁺ extracellular concentration

3 mM

mammalian neuron Cl^- extracellular concentration

120 mM

mammalian neuron Ca²⁺ extracellular concentration

1.2 mM

mammalian neuron Na⁺ equilibrium potential

+56 mV

mammalian neuron K⁺ equilibrium potential

-102 mV

mammalian neuron Cl^- equilibrium potential

-76 mV

mammalian neuron Ca²⁺ equilibrium potential

+125 mV

the equilibrium potential for any individual ion x can be determined with this equation

nernst equation

nernst equation

$$E=\frac{RT}{zF}\ln\left(\frac{\left\lbrack x\right\rbrack o}{\left\lbrack x\right\rbrack i}\right)$$

Simplified nernst equation for room temp

$$E=\frac{58}{z}\log_{}\left(\frac{\left\lbrack x\right\rbrack i}{\left\lbrack x\right\rbrack o}\right)$$

simplified nernst equation for body temp

$$E=\frac{61.5}{z}\log_{}\left(\frac{\left\lbrack x\right\rbrack i}{\left\lbrack x\right\rbrack o}\right)$$

The net electrochemical gradient acting on an ion, calculated as the difference between the membrane potential and the equilibrium potential

driving force

the membrane potential for a particular ion past which the ion flow reverses direction

reversal potential

Driving force equation

$$DF=Vm-Ex$$

negative driving force means

current is flowing inwards

positive driving force means

current is flowing outwards

goldman-hodgkin-Katz Equation uses

used to calculate the reversal potential

goldman-hodgkin-Katz Equation

$$E_{rev}=\frac{RT}{F}\ln\left(\frac{P_{k}\left\lbrack K_{}\right\rbrack_{o}+P_{Na}\left\lbrack Na\right\rbrack_{o}+P_{Cl}\left\lbrack Cl_{}\right\rbrack_{i}}{P_{k}\left\lbrack K_{}\right\rbrack_{i}+P_{Na}\left\lbrack Na\right\rbrack_{i}+P_{Cl}\left\lbrack Cl_{}\right\rbrack_{o}}\right)$$

Sodium cation driving force at resting membrane potential

-126 mV

Potassium cation driving force at resting membrane potential

+32 mV

Chlorine anion driving force at resting membrane potential

+6 mV

Calcium cation driving force at resting membrane potential

-195 mV

Ohm’s Law for Membrane Biophysics

I_x=g(V_m-E_x)