Final answer:
Ions move down their concentration gradient from higher to lower concentrations and are influenced by electrical gradients across the cell membrane, creating an electrochemical gradient vital for nerve and muscle function.
Step-by-step explanation:
The diffusional and electrical gradients relate to the behavior of ions in that ions tend to move from areas of high concentration to areas of lower concentration, which is known as moving down the concentration gradient. This movement is due to the kinetic energy that causes them to spread out or diffuse. In addition to the concentration gradient, there is an electrical gradient across the plasma membrane caused by the differential distribution of ions across the membrane. Ions are driven by both the concentration difference and the membrane potential.
Positive ions (cations) are attracted to the negative interior of the cell, thus moving against the electrical gradient while seeking lower concentration areas. Negative ions (anions) are typically repelled and move towards areas with a higher positive charge. These forces together create what is known as the electrochemical gradient, which is crucial for the functioning of muscle and nerve cells. Passive transport, including diffusion, does not require the cell to expend energy, as ions move according to this gradient. However, when cells require ions to move against the concentration gradient, active transport mechanisms that use energy come into play.