Is the return to negative potential as K+ exits through voltage-gated K+ channels hyperpolarization, repolarization, threshold, depolarization, or all-or-none?
Answer (1)
Repolarization is the process where the membrane potential returns to its resting (negative) state.
K+ exiting through voltage-gated channels is a key event in repolarization.
Other options like hyperpolarization, threshold, depolarization, and all-or-none do not accurately describe this process.
The correct answer is \boxed{Repolarization}.
Explanation
Understanding the Question The question asks us to identify the correct term that describes the return to a negative potential as potassium ions (K+) exit through voltage-gated K+ channels. We need to consider the definitions of the given options and choose the one that best fits this description.
Analyzing the Options Let's analyze each option:
Hyperpolarization: This refers to a state where the membrane potential becomes more negative than the resting potential. While K+ efflux can contribute to hyperpolarization, the question specifically asks about the return to a negative potential, not necessarily going beyond the resting potential.
Repolarization: This is the process where the membrane potential returns from a depolarized state (more positive) back towards the resting membrane potential (negative). The exit of K+ ions is a key event in repolarization.
Threshold: This is the specific membrane potential that must be reached to trigger an action potential. It's a point, not a process of returning to a negative potential.
Depolarization: This is the opposite of what the question describes; it's when the membrane potential becomes less negative (more positive).
All-or-none: This principle refers to the fact that an action potential either fires completely or not at all, regardless of the stimulus strength, once the threshold is reached. It doesn't describe the return to a negative potential.
Determining the Correct Term Based on the definitions, repolarization is the term that accurately describes the return to a negative potential as K+ exits through voltage-gated K+ channels.
Final Answer Therefore, the correct answer is Repolarization .
Examples
Understanding repolarization is crucial in various real-world applications, such as designing drugs that target specific ion channels to treat neurological disorders. For example, medications that prolong repolarization can be used to manage certain types of cardiac arrhythmias by extending the refractory period of heart cells. This concept also applies to understanding nerve impulse transmission and muscle contraction, where proper ion channel function is essential for normal physiological processes. By grasping the principles of repolarization, students can better appreciate the complexities of cellular communication and its implications for health and disease.
