The post-ganglionic nerve fibres of sympathetic nervous system are adrenergic ie; they release the neurotransmitter nor-adrenalin at their termination. The sympathetic nerves stimulate the adrenal glands to secrete adrenaline, The post-ganglionic para-sympathetic fibres are cholinergic i.e., they release a chemical substance acetyl choline, a neurotransmitter, at their endings for the transmission of nerve impulses.