Animal cells generally have a higher concentration of Na+ outside of the cell than inside the...

Animal cells generally have a higher concentration of Na+ outside of the cell than inside the cell and a membrane potential around -70 mV. When an Na+ moves into an animal cell, how does that movement impact the membrane potential? How does that movement impact the Na+ concentration gradient?

Explain what an equilibrium potential for an ion is, what the resting membrane potential is, and how they are different.

Solutions

Expert Solution

Answer (part 1)

Na+ is usually present at a much higher concentration outside of a cell than inside. If a channel route or carrier protein gets open, Na+ ions will move down their concentration gradient and move to the interior of the cell, making the inside of the cell more positive relative to outside.

Because of this, the sodium equilibrium potential (the electrical potential difference across the cell membrane that exactly balances the Na+ concentration gradient) will be positive. So, in a system where Na+ is the only permeant ion, the membrane potential will be positive.

Answer (part 2)

The electrical potential difference across the cell membrane that exactly balances the concentration gradient for an ion is known as the equilibrium potential.

Resting Membrane Potential (RMP) is the voltage (charge) difference across the cell membrane when the cell is at rest. RMP is a product of the distribution of charged particles (ions).

gladiator answered 1 year ago

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