Final answer:
In an environment with no sodium, both skeletal muscle cells and cardiac muscle cells would be unable to contract and perform their functions.
Step-by-step explanation:
If a skeletal muscle cell is in an environment with no sodium, it would not be able to generate action potentials and contract. Sodium ions play a crucial role in depolarizing the cell membrane and initiating muscle contractions. Therefore, without sodium, the skeletal muscle cell would not be able to function properly.
Similarly, if a cardiac muscle cell is in an environment with no sodium, it would also be unable to generate action potentials and contract. Cardiac muscle cells rely on depolarization of the cell membrane to initiate contractions and maintain a regular heart rhythm. Without sodium, the cardiac muscle cell would lose its ability to contract and impact the overall functioning of the heart.