Flashcards in Physiology Chapter 2-Membrane potential Deck (19):
What is membrane potential?
Difference in electrical potential between the ECF and ICF.
What is membrane potential measured in?
What is resting potential?
Constant membrane potential in the cells of non-excitable cells.
What are the main ions responsible for the membrane potential?
Sodium, potassium and anions.
What is the equilibrium potential of potassium?
What two forces contribute to potassium's equilibrium potential?
The concentration gradient pushing it out of the cell and the electrical potential pulling it in.
What is the sodium equilibrium potential?
How do sodium and potassium affect the membrane potential?
The greater permeability exists for potassium and therfore drives the membrane potential towards its eqb potential. It is however maintained at -70mV due to the input of sodium.
How do excitable tissues use membrane potential?
They can rapidly and efficiently alter their membrane permeabilities to specific ions in response to appropriate stimulation bringing about fluctuations in membrane potentials.
What is polarization?
Charges are separated across the membrane, so the membrane has potential. Any time the value of the membrane potential is not 0mV, the membrane is in a state of polarization.
What is depolarization?
A reduction in the magnitude of the negative membrane potential.
What is repolarization?
The membrane returns to resting potential after having been depolarized.
What is hyperpolarization?
An increase in the magnitude of the negative membrane potential.
Changes in ion movement brought about by changes in membrane permeability are done in response to what?
What are different triggering events?
A change in the electrical filed in the vicinity of an excitable membrane.
An interaction of a chemical messenger with a surface receptor.
A spontaneous change in potential caused by inherent imbalances in the leak-pump cycle.
What are leak channels?
Membrane channels that are open all the time. Permit unregulated leakage of their chose ion across the membrane through the channels.
What are gated channels?
Have gates that can alternatively open, permitting ion passage through the channels or;
closed, preventing ion passage through the channels.
What are the four different types of gated channels?
Voltage gated, chemically gated, mechanically gated and thermally gated.