So one of the things I think is important for everybody to understand really is if you’re going to talk about how something’s going to break down, you need to understand how it functionally works and the components of it when it’s working in a normal pattern. So the stress response system is actually quite detailed, and it’s not mainly, it’s not just hypothalamus, pituitary, adrenal. Although those are the primary organs involved. The stress response system is actually quite a bit more complex than that, and involves a lot of different structural and chemical components.

If you’re looking at just the central system, the CNS system (central nervous system) has the higher brain, which is, I guess to put it briefly, involved in assessing what your body perceives as a stress and is it something that you need to be stressed about; is it something that you need to flee from or fight.

The hypothalamus really is the key center as far as production of the stimulating hormones that affect the adrenal glands and other tissues. And actually it’s interesting because there’s a whole body of literature just talking about CRH by itself as a stress hormone, and all the different things that CRH, corticotrophin releasing hormone, does independent of the effects of cortisol. It parallels quite similarly the effects of cortisol. Then within the brain stem, the other primary location is down here [points to bottom box: LC/NE system in medulla and pons (norepinephrine)] when you’re talking about the acute stress response and catecholamine production.

Then there’s the peripheral components – the peripheral limbs of the HPA axis, the parasympathetic nervous system, the sympathetic nervous system and all the different neurological pathways and chemicals and connections involved there.

But if we’re going to try to simplify it, at least for the topic of this discussion, the primary hormonal components and primary structural components are these: the CNS structures which produce the CRH and AVP (vasopressin). Actually AVP in and of itself does not have a lot of ability to result in cortisol release, but it works together with CRH to do a synergistic effect on ACTH production. Then you have ACTH in the pituitary, which then gives rise to these three basic main hormones – obviously not an inclusive list. The adrenal makes quite a few other hormones besides these three.

But then there are all these other influential factors. There’s cytokines, and as you’ll find through our discussions today, you’re going to get an appreciation of the intricacy between the immune system and the stress response – different neurotransmitters, different amino acids, angiotensin-II (AT-II), catecholamines – there’s all of these different things that are playing a role in the stress response, usually to help up-regulate it.