WITH COMPLETE VERIFIED SOLUTIONS LATEST UPDATE
Neurotransmitter vs hormone
catecholamines are neurotransmitter and also hormones.
- Neurotransmitter: released from a neuron to an adjacent cell
- hormone: released from endocrine glands into circulation/ to adjacent cells
Biosyntheis
Sites:
- adrenal medulla: mainly epinephrine
- neurons of sympathetic nerves and CNS: mainly norepinephrine, some dopamine
Metabolism of free catecholamines
Catecholamines have a very short plasma half-life because they are taken into cells
quickly. They are metabolized in those cells
Mian metabolites of lab tests
- homovanillic acid (HVA) from dopamine
- Normetanephrine from norepinephrine