Final answer:
The myelin sheath, created by glial cells, surrounds vertebrate axons providing insulation. It contains specific gaps, called nodes of Ranvier, that aid in the transmission of electrical signals. This structure enhances the speed of signal delivery, especially critical in human motor neurons.
Step-by-step explanation:
The insulating material that covers many vertebrate axons is known as the Myelin sheath. This specialized structure is initiated by glial cells and acts as an insulator to keep the electrical signal from dissipating as it travels down the axon. The myelin sheath essentially generates a cover around the axon, similar to the plastic or rubber insulating electrical wires. However, an important feature of the myelin sheath is the presence of gaps, referred to as nodes of Ranvier, which play a crucial role for electrical signals transmission along the axon. An axon covered with the myelin sheath can drastically increase the speed of electrical signal conduction. This is of great importance, considering that the axon from a human motor neuron can span up to a meter long – from the base of the spine to the toes.
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