Your Body Tries to Fight Stressors and Prevent and Heal Injury
When our bodies experience stress, they prepare to both fight and to prevent and heal injury.
To "rev" the body up, the hypothalamus activates the pituitary gland which releases ACTH which in turn, releases two types of chemicals. The first type is catecholamines, epinenphrine and norepinephrine. These chemicals have the effect of making the body more "aroused." Epinephrine is the substance that is commonly referred to as adrenaline. The chain of events makes our heart rate increase and makes us feel more energetic and alert.
To help heal injury, the second kind of chemical, corticosteriods, resist the negative effects of stress. (e.g., one corticosteriod, cortisol, decreases swelling that occurs when the body is injured.)
When our bodies experience too much stress, our health is affected too.