The potential generated due to freely diffusible ion across a membrane is measured by :
## **Core Concept**
The question tests understanding of the electrical properties of cell membranes, specifically the concept of equilibrium potentials generated by freely diffusible ions. This concept is crucial in physiology, particularly in understanding how ions move across cell membranes and generate electrical potentials.
## **Why the Correct Answer is Right**
The Nernst equation is used to calculate the equilibrium potential (also referred to as the Nernst potential) for an ion. This equation takes into account the concentration gradient of the ion across the membrane and the temperature. The Goldman-Hodgkin-Katz equation, on the other hand, calculates the resting membrane potential by considering the permeability and concentration gradients of multiple ions. However, when specifically considering the potential generated due to a freely diffusible ion across a membrane, the Nernst equation is the most directly relevant. This equation provides a way to calculate the equilibrium potential for a specific ion, assuming the membrane is selectively permeable to that ion.
## **Why Each Wrong Option is Incorrect**
- **Option A:** The Goldman-Hodgkin-Katz equation is used to calculate the resting membrane potential by taking into account the concentration gradients and permeabilities of multiple ions, not just one freely diffusible ion.
- **Option B:** This option seems to refer to an equation or concept not directly related to the standard equations used in physiology for calculating membrane potentials.
- **Option D:** While the resting membrane potential is an important concept, it is not specifically the potential generated due to a single freely diffusible ion but rather the result of multiple ionic influences.
## **Clinical Pearl / High-Yield Fact**
A key point to remember is that the Nernst equation is specifically used for calculating the equilibrium potential for a single type of ion, assuming the membrane is only permeable to that ion. This concept is foundational for understanding how action potentials are generated in neurons and muscle cells.
## **Correct Answer:** . Nernst Equation