Membrane-02 Flashcards
How many mV is the Resting Membrane Potential (RMP), explain why it is like this regarding K+, Na+ and Cl- ions?
about -70 mV because the membrane is most permeable to K+, but Na+ and Cl- ions also contribute.
Why is the Resting Membrane Potential -70 mV and not -90 mV regarding K+, Na+ and Cl- ions?
The membrane is primarily permeable to K+, but Na+ and Cl- ions also diffuse, making the RMP closer to -70 mV.
What equation is used to calculate the membrane potential considering K+, Na+ and Cl- ions and how does the equation do this?
The Goldman Equation takes into account the permeability of K+, Na+, and Cl- ions.
What happens to the inside of the cell when the membrane becomes more permeable to Na+, and what is the new mV?
The membrane potential becomes positive inside, reaching ENa+ = +60 mV.
which direction (in or out) is Cl- pushed across the cell membrane and why, what is the result of this?
Cl- ions are pushed out of the cell due to large anion proteins inside, leading to a higher concentration of Cl- outside.
what stage of action potential generation do Na+ channels open, what does this allow Na to do, and what is the result of this?
Na+ channels open during depolarization, allowing Na+ to enter the cell, which generates an action potential.
what is the gist of how a signal is generated, what type of membrane is required to do this and what does it have?
a short, fast change in membrane potential used as a signal, typically occurring in excitable membranes with voltage-gated Na+ channels.
what is the All or None Principle?
Once the threshold is reached, the action potential has the same magnitude regardless of stimulus strength.
What stage does the Refractory Period occur after, what happens to the NA channels and what is the result of this?
The period after an action potential when Na+ channels are inactivated and the membrane cannot produce another AP.
What is the difference between Absolute and Relative Refractory Periods in terms of Na+ channels and what is the result of this?
Absolute RP: No Na+ channels are reconfigured; Relative RP: Some channels are reconfigured, allowing a potential AP.
What happens to Na+ channels during a Depolarization Block?
Keeping the membrane depolarized (above threshold) prevents Na+ channels from reactivating, blocking further action potentials.
How do the K+ channels cause After-Hyperpolarization?
Extra K+ channels open after an AP, causing the membrane potential to drop below the resting membrane potential, leading to hyperpolarization.
How can the effect of a Depolarization Block be increased and what is the result of this regarding Na+ channels?
By increasing K+ in the extracellular space (e.g., with KCl injection), leading to permanent Na+ inactivation.
What is the gist of what happens during After-Hyperpolarization, what is the charge of the membrane like?
The membrane potential temporarily drops below the resting potential, becoming more negative than usual.
