Final answer:
Sodium ions enter cells via facilitated diffusion through sodium channels and are actively transported by the sodium-potassium pump.
Step-by-step explanation:
In your body, sodium ion (Na+) concentration levels are higher outside of your cells than on the inside. Sodium ions would enter your cells primarily through a process called facilitated diffusion.
This process utilizes membrane proteins that form sodium channels, allowing Na+ ions to move down their concentration gradient into the cell without expending cellular energy.
Another important mechanism that helps maintain the sodium gradient is the sodium-potassium pump, which actively transports sodium out of the cell and potassium into the cell using ATP.