General Adaptation Syndrome

General adaptation syndrome (GAS) is a general pattern of physiological responses due to a persistent stress state, also known as universal adaptation syndrome, and was proposed by the Canadian physiologist Hans Selye. In 1936, Selye observed through experiments that injecting mixed homogenates of tissues from allogeneic animals (such as bovine ovaries) or chemicals (such as alcohol and formaldehyde) into the abdominal cavity of experimental animals always causes hyperplasia of adrenal cortex, obvious atrophy of thymus, spleen and lymph nodes, significant decrease in eosinophils, and superficial ulcer of gastric mucosa to these animals. Independent of the type and nature of the injection, these reactions are nonspecific, and defined by Selye as stress.

Selye divided the GAS into three stages according to the process and manifestation of general adaptive response: (1) The alarm stage. The symptoms are weight loss and enlargement of adrenal cortex. Adrenal cortex secretes a lot of...