Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

What is the role of the myelin sheath in neurons?

1. Increase neurotransmitter release

2. Cover neurons and provide insulation

3. Conduct impulses towards the cell body

4. Facilitate energy production

The correct answer is: Cover neurons and provide insulation

The myelin sheath plays a crucial role in the functioning of neurons by covering them and providing insulation. This insulating layer is formed by glial cells, which wrap around the axon of a neuron. The primary function of the myelin sheath is to increase the speed at which electrical impulses, or action potentials, travel along the axon. By insulating the axon, the myelin sheath allows the electrical signal to jump between nodes of Ranvier—gaps in the myelin—through a process called saltatory conduction. This enhances the efficiency of nerve signal transmission and is vital for rapid communication within the nervous system. The other options suggest functions that do not align with the role of the myelin sheath. For instance, increasing neurotransmitter release pertains to synaptic functioning rather than the transmission of electrical impulses down the axon, while conducting impulses toward the cell body describes the function of dendrites. Facilitating energy production relates to metabolic processes within the cell rather than the specific insulating function of the myelin sheath. Thus, the correct answer accurately reflects the primary role of the myelin sheath in neuron physiology.