Final answer:
Chromaffin cells are modified postganglionic sympathetic neurons that secrete catecholamines such as epinephrine and norepinephrine, and are part of the sympathetic nervous system.
Step-by-step explanation:
Chromaffin cells are specialized cells found in the adrenal medulla, which is part of the autonomic nervous system. Specifically, they are modified postganglionic sympathetic neurons that secrete catecholamines, including epinephrine (adrenaline) and norepinephrine (noradrenaline). These cells develop from the neural crest alongside the sympathetic ganglia, underscoring their role as neurosecretory cells within the sympathetic nervous system (SNS). Chromaffin cells respond to the stimulation from preganglionic sympathetic fibers by releasing their catecholamines directly into the bloodstream, which then act as hormones to affect distant cells, contributing to the body's fight-or-flight response. The adrenal medulla, through the action of chromaffin cells, effectively functions as a sympathetic ganglion.