Membrane Potentials: Action Potential Generation and Propagation
Refer to pages 376 to 383 to help you answer the following questions.
An action potential will only be fired if the membrane potential of an excitable cell reaches a certain value. What is the general name for this particular membrane potential?
An action potential is fired when, and only when, this particular membrane potential is reached because it is this membrane potential that a large population of v______--g______ s______ c______ is sensitive to. Therefore, when this value is reached and an action potential is fired, ______ ions flow ______ (into or out of) the cell.
The flow of this ion across the membrane causes the membrane potential to become more ______ (positive or negative). Consequently, this first phase of an action potential is also known as the d______ phase.
The next phase of the action potential is known as the ______ phase, which serves the function of reestablishing the cell's resting membrane potential.
During this phase, how does the sodium permeability to the cell membrane compare to the sodium permeability when the cell is at rest? Explain your answer.
During this phase, how does the potassium permeability to the cell membrane compare to the potassium permeability when the cell is at rest? Explain your answer.