Although stress aids in our survival, living in a chronic state of stress can be detrimental to both the body and the mind.
This is how it works:
When the brain perceives a threat, several structures within it are activated and go on alert such as the hypothalamus, amygdala, and the pituitary glands. These structures trade information with one another and send signals to the body to prepare for fight or flight.
The body then releases an overflow of hormones such as adrenaline, which makes the lungs and heart work harder to flood the body with oxygen. The adrenal glands will also release extra cortisol to help the body convert sugar into energy and the nerve cells will release norepinephrine that will tense the muscles and sharpen the senses to prepare for action.
When the threat is gone, epinephrine and norepinephrine levels drop. If danger occurs too often, those chemicals can damage the arteries. Chronic stress even at low levels keeps corticoids in circulation resulting in a weakened immune system, suppression of the reproductive system, loss of bone mass, and memory problems.