**Question:** Concentration of sodium channel in nerve in per square foot is

A. 10,000 channels
B. 1,000 channels
C. 100 channels
D. 10 channels

**Core Concept:** Sodium channels are transmembrane proteins found in excitable cells, such as neurons, that play a crucial role in the generation and propagation of action potentials. They are essential for the nerve impulse transmission process.

**Why the Correct Answer is Right:** In the context of nerve cells, the correct answer refers to the number of voltage-gated sodium channels present in a given area, which is approximately 1,000 channels per square foot. These channels are responsible for the inward flow of sodium ions during depolarization, a critical step in the generation and propagation of action potentials.

**Why Each Wrong Option is Incorrect:**

A. 10,000 channels (too high): This option greatly exceeds the actual number of sodium channels present in a nerve cell. An excessive number would be biologically implausible and not reflect the actual functionality of the sodium channels in nerve cells.

B. 1,000 channels (too low): This option is also incorrect because it significantly undervalues the actual number of sodium channels involved in nerve cell function. An underestimated number does not accurately represent the role of sodium channels in nerve impulse transmission.

C. 10 channels (too low): Similar to option B, option C significantly underestimates the number of sodium channels necessary for nerve cell function. A low number fails to depict the actual role of sodium channels in nerve impulse transmission.

D. 10 (incorrect unit): This option presents the number of sodium channels but uses an incorrect unit (square centimeter). The correct unit is "per square foot," which is more suitable for describing the distribution of ion channels in a biological context.

**Clinical Pearl:** Understanding the proper concentration of sodium channels in nerve cells is essential for grasping the role they play in the generation and propagation of action potentials, which is crucial for proper nerve cell function and communication. The correct answer of 1,000 channels per square foot provides a reliable estimate of the number of sodium channels necessary for efficient nerve impulse transmission.