Table 6.

Definitions of stress, stress system, homeostasis, adaptation, adaptedness, adaptability, resilience, adaptive homeostasis, adaptive stress response (hormesis), adaptive stress system, and adaptive signaling pathways

Stress is a state of threatened homeostasis, 132 depending on severity and duration, stress can have quite a different impact on the organism—from beneficial to harmful: chronic eustress (too little stress), acute stress (optimum stress) initiate beneficial adaptive stress response, while when stress increases beyond a certain level ‐ acute distress (too much stress), and chronic stress (burnout)—it leads to harmful health effects and can cause numerous diseases. In this context, adaptogens act like chronic eustress activating adaptive stress response, resilience and overall survival.

Stress system is the neuroendocrine–immune complex, Adaptive stress system includes all physiological systems involved in the process of adaptation to stress. 133

Homeostasis is a complex dynamic equilibrium/steady state, maintained by coordinated physiological processes in the organism. 132 , 134 In other words, homeostasis is the ability of a living organism or cell to maintain the state of internal balance despite changes in the conditions around it, while stress—is temporary inability to maintain this steady state.

Adaptation as an active process of responding to challenges which includes behavioral, physiological, structural, and genetic changes upon environmental impacts that are beyond the biologically adequate ranges. 135

Adaptedness is a result of adaptation process when a positive outcome, that is, survival and reproduction, is achieved in the face of adversity. Adaptedness is a state that has a capacity for adaptation. 136

Adaptability is an ability of an organism to alter itself or its responses to the changed circumstances or environment. Adaptability shows the ability to learn from experience and improves the fitness of the learner as a competitor. 137

Resilience is the ability to maintain or quickly return to a stable physical and psychological equilibrium despite experiencing stressful events. 138

Adaptive homeostasis is defined as the transient reversible adjustments of the homeostatic range in response to exposure to signaling molecules or events. 131 Adaptive homeostasis is the cellular or organismal capability to adjust the homeostatic range in response to herbal adaptogens. 17 In this context, adaptogens increase homeostatic range to the level of adaptive homeostasis activating adaptive stress response resulted in increased resilience and overall survival, Figure 1.

General adaptation syndrome–three phase response including nonspecific reactions (thymus atrophy, adrenal, hyperplasia, stomach ulceration, increased secretion of cortisol and catecholamines, etc.) of organisms evoked to stress: (i) alarm phase, (ii) phase of nonspecific resistance, following which symptoms disappear, and (iii) phase of exhaustion, when the same symptoms reappear, followed by death. 139 , 140 Adaptive stress response (hormesis) is the ability of a cell, tissue, or organism to better resist stress damage by prior exposure to a lesser amount of stress is known as adaptive response. It is observed in all organisms in response to a number of different cytotoxic agents.