M&R - Membrane Potential Flashcards
How are membrane potentials expressed?
As potential inside the cell vs outside
What is membrane potential?
The electrical potential difference across the membrane.
What are membrane potentials measured in?
mV
How is resting potential established?
Selectively permeable membrane results in ion channels carrying ions across the membrane. This rapid flow of ions down their conc gradients results in resting potential.
What direction does sodium move across a membrane?
into the cell
What direction does potassium move across a membrane?
Out of the cell
What direction does chloride move across a membrane?
Into the cell
What direction does calcium move across a membrane?
Into the cell
Which ion movement dominates membrane potential in most cells?
Potassium
What happens when the chemical (diffusion) and the electrical gradient across the membrane is equal?
There is no NET movement of ions but a negative resting potential.
What is the Nernst equation?
This allows us to calculate the membrane potential at which K+ will be in equilibrium.
What is the potential for the Nernst equation of potassium?
-95mV
What is the real cell membrane like?
As well as potassium channels there are also sodium, calcium and chloride.
This alters membrane potential
How is overall membrane potential calculated?
Goldman- Hodgkin - Katz
What is depolarisation?
A decrease in the size of membrane potential.
Cell interior becomes less negative
