Allostatic model explanation?

[playsimme]

This model is confusing as hell
I read through the oxford and it doesn't actually really touch on it. The purple book I'm skeptical about but it explains it alright..?
Anyone care to explain it clearly? I get it SORTOF but it's rather .. odd? Apparently it's biopsychosocial so .. ya that would be nice.

[Zafaraaaa]

Allostatic model pretty much says that the body constantly fluctuates and changes (through fluctuations and changes in allostatic systems like the HPA axis, autonomic Nervous system) to maintain stability to address unpredictable internal and external events - this means allostasis is the complete opposite of homeostasis which said that the body remains the same and constant to maintain stability

Because Allostasis results in bodily change & fluctuation through regulating activity of the HPA axis, and the autonomic nervous system (sympathetic and parasympathetic), and the immune and Cardiovascular systems - all these systems work to protect the body through everyday internal and external events that may be a threat. E.g. the HPA axis might provoke the adrenal glands to produce adrenaline & noradrenaline to help someone run away from a bear (LOL) or the sympathetic nervous system may increase a person's heart rate to flee from danger and then the parasympathetic N.S would bring one's heart rate back to normal after that danger has passed

In other words:
stressor --> allostatic response is turned "on" --> person successfully copes with stressor --> allostatic response turned "off" = when Allostasis is helpful
stressor --> allostatic response cannot be turned "on" properly --> nor can it be turned "off" properly --> Increased allostatic load = when Allostasis is damaging

Allostasis model adopts the Biopsychosocial framework to explain an individual's differing  bio, psych, social influences that may cause stress:
e.g.
Biological: the stressor (and its potential threat, if any) will determine whether the HPA axis and Sympathetic nervous system are to be activated
Psychological: How we interpret or "appraise" that stressor - a largely subjective process that may cause stress in one person but not in another
Social: The context in which that stressor occurs and our current circumstances will influence how much stress we'll experience

If this isn't right, someone correct me 

[playsimme]

Oh so it's that simple! Thanks for confirming! Btw - isn't the HPA a product of the sympathetic nervous system, so in reality the HPA is part of the sympathetic?

[Zafaraaaa]

Ummm I'm not too sure haha, I never thought about that - all I know is that the HPA axis is a part of the neuro-endocrine system (where the nervous system and endocrine systems interact) so umm it could be??