Resting membrane potential is close to the isoelectrical potential of:
**Core Concept**
The resting membrane potential is a critical concept in cellular physiology, reflecting the difference in electrical charge between the interior and exterior of a cell. At rest, neurons and other excitable cells maintain a negative electrical potential due to the distribution of ions across the plasma membrane. This potential is close to the isoelectrical point, where the electrical charges inside and outside the cell are balanced.
**Why the Correct Answer is Right**
The resting membrane potential is close to the isoelectrical potential because of the balance between the negative charge of potassium ions (K+) inside the cell and the positive charge of sodium ions (Na+) outside the cell. The cell membrane is selectively permeable, allowing K+ ions to leave the cell while preventing Na+ ions from entering. As a result, the electrical potential across the membrane becomes negative, close to the isoelectrical point. The Nernst equation and the Goldman-Hodgkin-Katz equation are mathematical models that describe this ion distribution and its effect on the resting membrane potential.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is not provided, so it cannot be evaluated.
* **Option B:** This option is not correct because the resting membrane potential is not close to the isoelectrical point due to the presence of other ions, such as chloride (Cl-) and calcium (Ca2+), that contribute to the membrane potential.
* **Option C:** This option is not correct because the action potential, not the resting membrane potential, is a rapid depolarization of the membrane, which is not close to the isoelectrical point.
**Clinical Pearl / High-Yield Fact**
The resting membrane potential is a critical determinant of neuronal excitability, and alterations in this potential can lead to various neurological disorders, such as epilepsy and neuropathic pain.
**Correct Answer:** Not provided. Please provide the correct options for a complete explanation.