The Basis of the Stress Reaction

The ubiquitous presence of stressful stimuli makes stress one of the most important causes of physiological or pathophysiological changes in an organism during its entire lifespan. The stressors can be divided (according to their nature) into physical, chemical, psychological, social and disturbing cardiovascular/metabolic homeostasis effects, which can affect multiple systems. Here we emphasize that although stress is classified according to its nature, multiple mechanisms are affected. We will focus on mechanisms of stress reaction with the aim of maximal brevity. The pathways that are activated in response to stressful stimuli with respect to specific types of stressors are described. The central processing of a stress response comprises central aminergic neurons, noncatecholaminergic brainstem neurons, hypothalamic nuclei and structures of the limbic system. As a response, specific efferent pathways are activated. Special attention is given to stress effects in the central nervous system and vital functions (heart function and respiration).