[12] Resting Membrane Potential Flashcards
Define “resting membrane potential”.
It is the voltage (charge) difference across the cell membrane when the cell is at rest.
What is the typical value of the resting membrane potential in most human cells?
Approximately -70 millivolts
Which ions are primarily involved in establishing the resting membrane potential?
- Potassium (K+)
- Sodium (Na+)
- Chloride (Cl-)
How does the concentration of potassium (K+) inside and outside the cell affect the resting membrane potential?
The cell has a higher concentration of K+ inside than outside, which tends to push K+ out of the cell, making the inside of the cell negatively charged.
How does the sodium-potassium pump contribute to the resting membrane potential?
It actively transports 3 Na+ out of the cell and 2 K+ into the cell, maintaining the ion concentration gradients.
How does the concentration of sodium (Na+) inside and outside the cell affect the resting membrane potential?
The cell has a lower concentration of Na+ inside than outside, which tends to draw Na+ into the cell, but this effect is less than the effect of K+ due to fewer Na+ leak channels.
How does the permeability of the cell membrane to different ions affect the resting membrane potential?
The cell membrane is more permeable to K+ than Na+, so K+ has a greater influence on the resting membrane potential.
What is the relationship between the resting membrane potential and action potentials in neurons?
The resting membrane potential provides the baseline from which action potentials (nerve impulses) occur.
What happens during the depolarization phase of an action potential?
The membrane potential becomes less negative (more positive) due to the influx of Na+ ions.
What happens during the repolarization phase of an action potential?
The membrane potential returns to its negative value due to the efflux of K+ ions.
What is hyperpolarization in the context of membrane potential?
It’s when the membrane potential becomes more negative than the resting potential, usually due to an increased outflow of K+ ions.
How does the chloride ion (Cl-) contribute to the resting membrane potential?
Although Cl- is mainly extracellular, it does not typically contribute much to resting membrane potential as its concentration gradient tends to balance out.
What is an ion channel in the context of resting membrane potential?
It’s a pore-forming protein that helps ions pass through the cell membrane.
Why is the resting membrane potential important for cell function?
It allows cells to maintain homeostasis and is crucial for the function of excitable cells (like neurons and muscle cells), enabling them to generate action potentials.
