Structure:
Norepinephrine is a biogenic amine hormone secreted by chromaffin cells.
These are postganglionic sympathetic neurons, and are thus part of the
sympathetic nervous system.
Function:
Norepinephrine, a catecholamine based upon it's chemical structure, is
a potent stimulant to constriction of arteries,
raising blood pressure, and redistributing blood flow to essential organs,
the brain, heart,
and the skeletal muscles. It has a smaller
effect on blood sugar, and on increasing the heart
rate. This set of responses has been called the "fight, or flight"
response. It shares some of the functions with epinephrine.
