Although it has been called the "Fight or Flight Hormone" adrenaline can be better described as 'Do it NOW!!! hormones." First things first, notice the 's.' Adrenaline isn't just one thing, but a cocktail of chemicals and hormones. For a more technical (but still a layman's) explanation look at what Wikipedia has to say about adrenaline.

(quote source)

Hmm. Usually to my layman's eye the author seems to know what he's speaking about BUT this time I'm surprised. I always thought adrenaline was a name for a single specific hormone rather than "a coctail of chemicals and hormones". Even the Wikipedia page the author himself links to doesn't seem to treat adrenaline as a collective term for many hormones; on the contrary it gives adrenaline one particular chemical formula, C9H13NO3

Is there more than 1 substance that can legitimately be called adrenaline?

Adrenaline = epinephrine. Different name, same chemical.

"Adrenergic receptors" is perhaps where things get more confusing. That is a family of hormone receptors (α1 α2 β1 β2...) that respond to endogenous hormones including epinephrine and norepinephrine, and medications that are adrenergic agonists.

Colloquially, people might say "adrenaline" to encompass all stress hormones, which is suggested by the phrase "Do it NOW!!! hormones." Stress hormones are not limited to adrenaline (epinephrine) but include multiple families of hormones that are released in response to stress. I like the way this is phrased in a journal of endocrinology:

In response to stress, the level of various hormones changes. Reactions to stress are associated with enhanced secretion of a number of hormones including glucocorticoids, catecholamines, growth hormone and prolactin, the effect of which is to increase mobilization of energy sources and adapt the individual to its new circumstance.

Here's a simplified diagram of adrenergic receptors and activity. I say simplified because there are multiple other steps involved, and it includes many different actions of the chemicals.

E= epinephrine, NE= norepinephrine, DA = dopamine, etc

Adrenergic receptors

  • Nice answer. My question is, what type of stress are we addressing here? Is it, "There's a cop in my rear view mirror with flashing lights on telling me to pull over!" (fight or flight) or "I can't deal with all the demands made of me at work anymore! (chronic stress.) Different hormone cocktails? – anongoodnurse Nov 8 at 3:00
  • Why hello there, my dear lurking @anongoodnurse! That's an excellent question. The cocktails of acute and chronic stress do in fact differ. From the recesses of my synapses, chronic stress tends to be cortisol-predominant, in part because surges of epinephrine are short-lived due to a half life of just a few mins, whereas cortisol is at least an hour. But I don't remember the relative %ages or the biochem of transitioning from acute to chronic... Do you have some wisdom to share on the matter? :D – DoctorWhom Nov 8 at 5:16
  • I didn't go into as thorough of detail on acute vs chronic in the answer as I could have because it wasn't really in his question, but it's an interesting point. The inflammation of chronic stress is one of my fav hot topics right now, in part because of the emerging neuropsych research on the relationship between chronic inflammation and the pathophysiology of depression, anxiety, and other mental illnesses. Seems chronic stress really is harmful - who'd have guessed? – DoctorWhom Nov 8 at 5:28
  • Hmm, you're making me reassess my question. When does an acutely stressful event cross over into a response consistent with chronicity? I don't know that. I would have mentioned catecholamines and secondarily cortisol, and stopped there. "Seems chronic stress really is harmful - who'd have guessed?" hehe. At least it doesn't cause most ulcers. Barry Marshall is my hero. – anongoodnurse Nov 8 at 14:36

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