Module 03: Membrane Transport - Resting Membrane

Which ion gives the greatest contribution to resting membrane potential, and why?

K+, as most cells are more leaky to K+. As K+ leaks out of a cell, it leaves the ICF with a net negative charge.

If a cell's Vm = -70 mV and ENa+ = +50 mV, which way will Na+ ions move across the cell membrane?

Na+ ions will move into the cell.

Is a cell at true "rest" when it is maintaining resting membrane potential?

No, actually a cell uses active transport to create a gradient. The voltage simply appears to be unchanging.

The greatest electrical driving force on an ion to move into a cell is illustrated by which of the following examples?

Vm = -70 mV, ion = Ca++ (ECa++ = +110 mV)

The combination of a electrical and chemical concentration gradient across a cell membrane is referred to as a (an) __________ gradient.

electrochemical

The membrane potential of a single ion that exactly opposes the concentration gradient of an ion is known as __________.

equlibruim potential, Eion