What is the function of the myelin sheath?

The primary function of the myelin sheath is to speed up the transmission of electrical signals along the axons of neurons. It acts as an insulating layer, which allows electrical impulses, known as action potentials, to travel more efficiently. This insulation prevents the loss of electrical charge and enables the signals to jump between the Nodes of Ranvier, which are gaps in the myelin sheath. This process is called saltatory conduction and significantly increases the speed at which signals can be transmitted compared to unmyelinated axons. This efficiency is crucial for rapid communication within the nervous system.

In contrast, the other options refer to different aspects of neuronal structure and function. For instance, while the nucleus of a neuron is important for cell metabolism and genetic information processing, it is not specifically protected by the myelin sheath. Storing neurotransmitters is a function carried out by synaptic vesicles in the axon terminals, not by the myelin sheath. Similarly, connecting sensory and motor neurons is the role of interneurons or other pathways in the nervous system, rather than a function of the myelin sheath itself.