In: Anatomy and Physiology
The resting membrane of a cell is mostly due to:
A. |
high permeability of the cell membrane to K+ |
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B. |
high permeability of the cell membrane to Cl- |
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C. |
high permeability of the cell membrane to Na+ |
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D. |
the activity of the electrogenic pump |
The resting membrane of a cell is mostly due to high permeability of the cell membrane to K+.
Explanation:
The resting membrane potential of a cell is defined as the electrical potential difference across the plasma membrane when that cell is in a non-excited state.
The permeability for K+ is much higher, due to presence of K+ “leak” channels present in the plasma membrane, which allow K+ to diffuse out of the cell down its electrochemical gradient.
When the membrane is at rest, K+ ions accumulate inside the cell due to a net movement with the concentration gradient. The negative charge within the cell is created by the cell membrane being more permeable to potassium ion movement than sodium ion movement. Potassium ions are maintained at high concentrations within the cell while sodium ions are maintained at high concentrations outside of the cell. The cell possesses potassium and sodium leakage channels that allow the two cations to diffuse down their concentration gradient.