Final answer:
The sympathetic nervous system's preganglionic and postganglionic fibers work to initiate a 'fight or flight' response, whereas the parasympathetic system, although similarly structured, operates differently due to the varying lengths of its preganglionic and postganglionic fibers and the locations of the ganglia.
Step-by-step explanation:
The sympathetic nervous system is a part of the autonomic nervous system responsible for the 'fight or flight' response. The preganglionic sympathetic fibers originate from the lateral horn of the thoracolumbar spinal cord and project to the sympathetic chain ganglia or to collateral ganglia. They release acetylcholine (ACh) to excite the ganglionic neuron. Postganglionic fibers carry the signal to target effectors, releasing norepinephrine or ACh for sweat glands and blood vessels, affecting the organ's physiology. A special preganglionic connection exists with the adrenal medulla, releasing hormones into the bloodstream for a widespread systemic effect.
The parasympathetic division operates similarly, with long preganglionic fibers that connect to terminal ganglia located near target effectors. The shorter postganglionic fibers then reach the effector organs. In comparing sympathetic and parasympathetic systems, a significant difference is the relative length of preganglionic and postganglionic fibers and the location of their corresponding ganglia.