What is the name of the insulating layer that surrounds neurons to increase signal transmission speed?

The correct answer is myelin sheath. The myelin sheath is a fatty layer that surrounds the axons of many neurons. Its primary function is to insulate the axons, which allows electrical signals to be transmitted more rapidly along the nerve cells. This insulation is crucial for efficient communication between neurons, as it facilitates a process known as saltatory conduction, where the action potential jumps from one node of Ranvier to the next. This not only increases the speed of signal transmission but also conserves energy in the neuron.

In contrast, the axon is the long, slender projection of a neuron that transmits electrical impulses away from the cell body. While it plays an essential role in signaling, it does not provide insulation. Dendrites are the branching structures of a neuron that receive signals from other neurons, but they are not involved in the insulating process. Finally, a neuron is the basic functional unit of the nervous system, encompassing various components, including the cell body, dendrites, axon, and myelin sheath. Each of these components contributes to the overall function of signaling in the nervous system, but it is the myelin sheath that specifically enhances signal transmission speed.