The cell membrane serves many functions. One of the cell membranes functions is to help the cell maintain homeostasis. How does the cell membrane do that ?

The cell membrane help to maintaining homeostasis by regulating the flow of substances through it and by recognizing potentially harmful agents to the cell.

Explanation:

Cellular membrane is constituted by a lipidic bilayer, whose characteristics allow it to behave as a semi-permeable membrane to the passage of substances.

The selective permeability of the membrane makes it possible to regulate the passage of water, molecules and ions through it into the cell and from there into the extracellular space, a characteristic that allows the maintenance of homeostasis.

Additionally, the cell surface can identify foreign and potentially harmful agents, which can affect the internal balance, preventing in most cases their passage into the cell.  

the cell cycle is the final answer! : )

voluntary muscles are controlled by the cerebellum.