The long extensions of nerve cells are crucial for what purpose?

The long extensions of nerve cells, known as axons, play a critical role in efficient signal transmission throughout the nervous system. These extensions allow nerve cells to communicate over long distances by transmitting electrical impulses, or action potentials, from one part of the body to another.

The structure of the axon, including its length and the presence of myelin sheaths, enhances the speed and efficiency of these signals. Myelin, a lipid-rich substance, acts as an insulator, allowing the electrical impulses to jump between nodes of Ranvier, which reduces the time it takes for the signal to travel. This is essential for quick reflexes and overall coordination of body responses.

Each of the other choices, while important in their own contexts, do not directly relate to the primary function of nerve cell extensions. Protecting the cell, producing energy, and storing nutrients are not the main roles served by the long extensions of nerve cells. Instead, efficient signal transmission is the primary reason these structures are so vital in the nervous system.