"the hypothalamus gets the news that for this trigger the response is lack of emotions flight response and starts shutting down the emotions.

the brain stem gets the message that the hypothalamus has shut down the emotions and slows down the breathing and heart rate and blood pressure because there is no more emotional responses happening. Because there is this emotional disconnection from the physical going on the brain stem slows things down almost but not quite entering a dream or sleep state. more like a foggy, everything is moving in slow motion, just here but not physically doing anything state for physical functioning called autopilot, automatic instead of consciously participating.

now because of being afraid of heights I am in a dissociation state physically and mentally."

I don't understand how a flight response shuts down emotions, I would think it would be an avoidance response. I sure understand the trigger increasing heart and breathing rates. That is how I know I am being triggered. But for me, if I am with someone who triggers me I do say I can/t talk about it and remove self from situation. If I am alone I just experience the physical signs, feel strong emotion and think "fighting" thoughts about it.