What are the gaps in the myelin sheath around a myelinated nerve fiber called?

The gaps in the myelin sheath around a myelinated nerve fiber are called Nodes of Ranvier. These nodes are essential for the proper functioning of myelinated neurons, as they are areas where the axon membrane is exposed. This exposure allows for the rapid propagation of action potentials through a process known as saltatory conduction, where the electrical signal jumps from one node to the next rather than traveling along the entire axonal membrane. This mechanism increases the speed of signal transmission and enhances the efficiency of communication within the nervous system.

The other terms mentioned refer to different structures or functions within the nervous system: synapses are junctions between neurons where signal transmission occurs; dendrites are extensions of a neuron that receive signals from other cells; and axon terminals are the endings of an axon where neurotransmitters are released to communicate with other neurons. Understanding these distinctions is crucial for grasping the overall structure and function of neurons in the nervous system.