How do some symptoms of illness being “an impending sense of doom” work, chemically?

Question

I don’t mean like mental Illness but like if
you have something physically wrong
with you just happen and you’re gonna
die. I read that the wrong type of blood
transfusion can cause that feeling as a symptom of something being seriously wrong with your body. What makes the doom feeling feel so different than other
feelings, chemically?

I know similar questions have been asked before, I’m not asking why it’s a symptom, I’m trying to ask how does the doom feeling happen, what kind of things does the body and brain do to produce that feeling, versus a normal adrenaline rush when you are in danger.

In: 7

Answer 1

It was explained to me to think about that same feeling during a typical hangover. But more overwhelming.