Lecture 2 Flashcards
Goldman Equation
Equilibrium membrane potential equation (each term is a diffusible ion species)
Na+ Equilibrium Potential
under certain circumstances, the permeability of Na+ (inward) can be dominant, causing a dramatic change in MP
Cl- ions
- Large proteins (that may only exit through exocytosis) tend to have negative charges and cause the Cl- ion to be pushed out of the cell
- Cl ions tend to be more concentrated on the outside of the cell (not due to the active pump)
Na+ Channels
- In order to generate a signal, the membrane opens a channel permeable only to Na+ ion (Voltage-gated Na+ channel- this is shit at normal resting MP)
Depolarization is necessary to open this Na+ channel
Action Potential
a short-lived impulse/ signal that is activated by the change in MP
Threshold
minimum depolarization necessary to induce the opening of Na+ channels (all or none principle)
The all-or-nothing law
is an important principle that describes how nerve cells either fire at full strength or do not.
Frequency Coding
as the intensity of a stimulus increases, the frequency or rate of action potentials, or “spike firing”, increases
Refractory Periods
After we generate an AP and inactivate the Na+ channels, we have a period in which all or some Na+ channels are inactivated
Absolute RP
none of channels are reconfigured
Relative RP
some but not all of channels are reconfigured (generally 2-5 ms duration)
Depolarization Block
If you permanently depolarize the membrane, keep it at 20 mV (above threshold), the Na+ channels will be permanently inactivated, and you will not be able to generate another AP
After-Hyperpolarization
you want this to act at a later phase to bring MP back down to resting levels (K+ channels need to repolarize the membrane)
