Knowledge center. Amphetamines are drugs which stimulate the CNS (central nervous system) - they are psychostimulant drugs-when overused they can be psychologically and physically addictive. As well as giving the user an enhanced feeling of wakefulness and focus, they also reduce appetite.mphetamines stimulate the central nervous system and the sympathetic part of the peripheral nervous system. Experts say that amphetamines enhance the synaptic activity of three neurotransmitters-dopamine, serotonin and norepinephrine.
Propagation of action potential along myelinated nerve fiber. Saltatory conduction (from the Latin saltare, to hop or leap) is the propagation of action potentials along myelinated axons from one node of Ranvier to the next node, increasing the conduction velocity of action potentials.n addition to increasing the speed of the nerve impulse, the myelin sheath helps in reducing energy expenditure over the axon membrane as a whole, because the amount of sodium and potassium ions that need to be pumped to bring the concentrations back to the resting state following each action potential is decreased.
The uninsulated nodes of Ranvier are the only places along the axon where ions are exchanged across the axon membrane, regenerating the action potential between regions of the axon that are insulated by myelin, unlike electrical conduction in a simple circuit.n addition to increasing the speed of the nerve impulse, the myelin sheath helps in reducing energy expenditure over the axon membrane as a whole, because the amount of sodium and potassium ions that need to be pumped to bring the concentrations back to the resting state following each action potential is decreased.