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.
Conduction of the action potential. In a myelinated axon (top), the myelin sheath prevents the local current (small black arrows) from flowing across the membrane.This forces the current to travel down the nerve fiber to the unmyelinated nodes of Ranvier, which have a high concentration of ion channels.earch Tips. View full-size image Conduction of the action potential In a myelinated axon (top), the myelin sheath prevents the local current (small black arrows) from flowing across the membrane.