The main function of an axon is to: generate local potentials when neurotransmitters bind their membranes generate and transmit signals in the form of action potentials function as the biosynthetic center of the neuron form the myelin sheath

the solute can move "downhill," from regions of higher to lower concentration, relying on the specificity of the protein carrier to pass through the membrane. this process is called passive transport or facilitated diffusion, and does not require energy.