Medicine. Stress is defined as a nonspecific response of the body to any demand made upon it which results in symptoms such as rise in the blood pressure, release of hormones, quickness of breath, tightening of muscles, perspiration, and increased cardiac activity. It is caused by any adverse stimulus, physical, psychological or emotional, internal or external, that tends to disturb the homeostasis of the organism.
See also oxidative stress and nitrosative stress.