Here are the essential concepts you must grasp in order to answer the question correctly.
Resting Membrane Potential
The resting membrane potential is the electrical charge difference across the plasma membrane of a cell when it is not actively sending signals. In skeletal muscle fibers, this potential is typically around -70 to -90 mV, primarily determined by the distribution of ions, especially potassium (K+), across the membrane. The negative charge inside the cell is maintained by the selective permeability of the membrane and the activity of ion pumps.
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Potassium Leak Channels
Potassium leak channels are integral membrane proteins that allow K+ ions to move out of the cell, contributing to the negative charge inside the cell. These channels are crucial for establishing and maintaining the resting membrane potential, as they enable K+ to flow down its concentration gradient. If these channels are blocked, the efflux of K+ is reduced, leading to a less negative resting membrane potential.
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Effect of Ion Concentration on Membrane Potential
The membrane potential is influenced by the concentration of ions inside and outside the cell, particularly K+. According to the Nernst equation, changes in ion concentration can significantly alter the resting membrane potential. If K+ leak channels are blocked, the concentration of K+ inside the cell would increase, resulting in a higher (less negative) resting membrane potential, which could affect muscle excitability and contraction.
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