- Resting State of the Neural Membrane:

In the resting state of the neural membrane, the concentration of ions inside and outside the cell is different. This difference creates a concentration gradient that can drive the movement of ions across the membrane.

- Diffusion:

Diffusion is the process by which particles move from an area of higher concentration to an area of lower concentration. It is a passive process that does not require energy. In the context of neural membranes, diffusion plays a crucial role in the movement of ions across the membrane.

- Concentration Gradients:

Concentration gradients refer to the difference in concentration of ions across the neural membrane. These gradients are established by the selective permeability of the membrane and the activity of ion channels and pumps.

- Movement of Ions:

Ions such as potassium (K+) and sodium (Na+) play a vital role in the functioning of neurons. The resting membrane potential is maintained by the movement of these ions across the membrane.

- Answer Explanation:

In the given question, we are asked about the direction of ion movement based on diffusion due to concentration gradients in the resting state of the neural membrane. The correct answer is option 'C', which states that Na+ would move into the cell.

- Explanation:

1. Resting State: In the resting state, the concentration of Na+ ions is higher outside the cell compared to inside the cell. This establishes a concentration gradient that drives the movement of Na+ ions.

2. Diffusion: Due to the concentration gradient, Na+ ions tend to move from an area of higher concentration (outside the cell) to an area of lower concentration (inside the cell) through the selectively permeable membrane.

3. Sodium Channels: The movement of Na+ ions across the membrane is facilitated by specific ion channels called sodium channels. These channels allow the passive movement of Na+ ions in response to the concentration gradient.

4. Equilibrium Potential: As Na+ ions move into the cell, the concentration inside the cell gradually increases. Eventually, the concentration gradient reaches a point where the movement of Na+ ions into and out of the cell becomes balanced. This is known as the equilibrium potential for Na+.

5. Resting Membrane Potential: The resting membrane potential is the electrical potential difference across the neural membrane in the absence of any external stimuli. It is primarily maintained by the movement of K+ ions out of the cell, driven by the concentration gradient.

To summarize, in the resting state of the neural membrane, diffusion due to concentration gradients drives Na+ ions into the cell. This movement is facilitated by specific ion channels and plays a crucial role in maintaining the resting membrane potential.