How an emergency temporary response “stress” can create cascades of long-standing problems in human being?

That’s the greatness about our brain. When a rat sees a cat – it develops an immediate stress response and run away from the place immediately and the stress response goes away. The rat cannot generate a stress response by visualising the cat from his memory and projecting thoughts about the cat when actually the cat is not there. It cannot also develop a neural circuit about a particular cat by repeatedly firing a bundle of neurons and then develop a self-sustained neural network which can even fire spontaneously now & then with the mildest probability of the original stimulus at sub-conscious level without even telling the rat. 

But now you already know from above discussions we can do that. Thus, even in absence of the original stimulus we can continuously fire the neurons unknowingly and can produce the chemical of stress. Now just Imagine you have developed such 100 neural nets due to past negative experience and they fire every now & then with mildest predictive probability of the original event. And they do so without telling you. Thus, without your knowledge the stress button remains pressed for long time. 

Now here are the cascades of events that happens in our body – once our brain gets the stress signal, it’s hypothalamus (the controller of the hormonal system in our brain) starts producing hormone related to stress ( CRH – Cortico-trophin releasing hormone ), which in turn release the hormone from our pituitary (ACTH – Adreno-cortico Trophic Hormone) and this in-turn release adrenaline from our adrenal gland. The stress hormone prepares our body for a 3F response (Flight, Fight & Fright response). It increases the body fuels that we would need for 3F- blood glucose level, stored body fuel by means of cholesterol, slows down our non-emergency but productive body activities i.e. digestions, regeneration & recovery activities. It increases gastric acid secretions and causes palpitation, irritability, lack of sleep, depression, sexual dysfunction, headache, generalised body ache etc. It robs you of your dopamine system, you are robbed of your creativity and holistic thinking without the alpha activity in your brain and now you seek for addictions for the temporary escape from the situation to the heavens of dopamine at the cost of your health. As in 3F mode our body puts away its vital energy source for excess body fuels and it spend less energy for our immunity and regeneration process thus it increases chances of infections and degenerative diseases. Persisting long, it also can give rise to anxiety and panic disorders, diabetes, cholesterol problems, heart diseases etc.