Anatomy Practice Exam 2025 – 400 Free Practice Questions to Pass the Exam

Myelin serves a critical function in the nervous system by segmentally encasing neuronal fibers, which facilitates faster transmission of electrical impulses along the axons. This insulating layer is composed of lipids and proteins, forming a myelin sheath around the axons of many neurons. The presence of myelin reduces the capacitance of the axon and allows for saltatory conduction, meaning that nerve impulses can leap from one node, or segment of unmyelinated axon, to the next. This significantly increases the speed of signal transmission, making myelination essential for efficient communication in the nervous system.

The other options do not accurately describe the primary role of myelin. For example, protecting the body's organs is more closely associated with connective tissue and membranes, while skeletal support is a function of bones and cartilage. Regulating body temperature pertains to thermoregulatory mechanisms in the body, which are unrelated to the function of myelin in neurotransmission. Thus, the choice that highlights myelin's role in enhancing both the speed and efficiency of neural communication is indeed the most accurate.