ICPP S6 Resting Membrane Potential Flashcards
What is meant by membrane potential?
The magnitude of an electrical charge that exists across a plasma membrane.
Membrane potential is always measure as the potential inside relative to potential of the extracellular solution.
True or false?
True
Do animal cells have -ve or +ve membrane potentials at rest?
Negative
What animal cells have the largest magnitude of membrane potential?
Cardiac and skeletal muscle.
What cells have the small magnitude of resting membrane potential?
Erythrocytes
What are 2 factors in the generation of a resting membrane potential?
Asymmetric ionic across the membrane.
Selective ion channels in the plasma membrane.
What are the electrolyte concentrations of Na+, K+ and Cl-?
Na+ - 140mM
K+ - 4.5mM
Cl- - 114mM
Are anions, other than Cl-, in higher concentration intracellularly or extracellularly?
Extracellularly
Intracellular - 40mM
Extracellular - 167mM
What 2 factors cause movement of ions across a plasma membrane?
Chemical/ Diffusion gradient
Electrical gradient
If chemical and electrical gradient are equal and opposite what does this mean in terms of ionic movement?
No ionic movement will occur.
What is the main determinant for the resting membrane potential and why?
The large number of open K+ channels at rest.
Means that K+ can leave and anions can not, leading to charge separation building up.
What is meant by the term equilibrium potential?
The membrane potential where the net flow through any open channels is 0.
What can be said about chemical and electrical forces in terms of equilibrium potential?
They are in balance.
What can we calculate the equilibrium potential using?
Nernst equation
If a membrane is only permeable to K+ only what will its membrane potential be?
Ek.
