3A Resting Membrane And Action Potentials (Electrophysiology I) Flashcards
Must exist across membranes of cells for the signals to be sent to any cells
electrical potential
electrical potential difference between the intracellular and extracellular fluid
membrane potential
electrochemical state of the cell at rest; no net movement of any ions across the cells
resting membrane potential (rmp)
rapid changes in the membrane potential that spread rapidly along the nerve fiber membrane
action potential
RMP of a large nerve fiber
-90mV
formation of RMP depends on:
- concentration gradient or concentration difference of an ion
- permeability of the ion across the cell membrane
main workforce responsible for establishing concentration gradients of K and Na
sodium potassium pump
concentration of Na and K intracellularly
Na = 10mEq/L K = 140mEq/L
concentration of Na and K extracellularly
Na = 142mEq/L K = 4mEq/L
K moves out of the cell to equalize the concentration and diffuses extracellularly through what channel?
potassium leak channel
moving out of K out of the cell causes the cytoplasm of the cell to be
electronegative since anions( negatively charged) the only ions left
exact point where the K moving out of the cell due to concentration gradient, equals the K moving back into the cell because of the electrical gradient
Equilibrium or Nernst Potential
electrical potential needed to attract K back into the cell to balance the concentration gradient
-94mV
used to calculate the diffusion potential when the membrane is permeable to SEVERAL DIFFERENT IONS
goldman equation
Keeps cells in “ready state” to fire an action potential
resting membrane potential
threshold potential
-55mV
channel that causes both depolarization and repolarization
voltage gated sodium channels
2 gates of voltage gated SODIUM channels
- activation gate - near the outside
* inactivation gate - near the inside
channel that increases rapidity of repolarization
voltage gated potassium channel
T/F: it is usually not possible without first repolarizing the nerve fiber in order for Na channels to open again
TRUE
Stages of Voltage gated Sodium Channels
- Resting stage -90mV
- Activation stage -90mV to +35mV
- Inactivation stage +35 to -90mV
Stages of Voltage gated potassium channels
- Resting stage
2. Slow Activation
period when voltaged gated sodium channel closes and the voltage gated potassium channels open
repolarization stage
stage wherein reestablishes the normal negative resting membrane potential
repolarization stage