In most resting cells, the concentration of sodium ions ishigher outside of cells compared with the intracellular fluid. Whencells are stimulated, sodium ion channels open, and sodium diffusesfrom the outside of the cell to the inside of the cell. Sodium ionconcentrations in a resting cell are an example of ___________, andsodium ion movement in a stimulated cell is an example of___________.
| the energy of motion; stored energy |
| potential energy; kinetic energy |
| kinetic energy; potential energy |
| chemical work; energy stored in chemical bonds |
