What is the physiological response to stress primarily based on?

The physiological response to stress is primarily based on the pituitary complex, which is an essential part of the endocrine system. When a person experiences stress, the hypothalamus in the brain first responds by signaling the pituitary gland. This gland releases various hormones, including adrenocorticotropic hormone (ACTH), which in turn stimulates the adrenal glands to produce cortisol and adrenaline. These hormones prepare the body for a "fight or flight" response by increasing heart rate, respiration, and energy availability.

While other systems and parts of the brain, such as the limbic system which deals with emotion, do play roles in how stress is perceived and managed, the pituitary complex is central to initiating the physiological hormonal response that characterizes stress reactions. The brainstem and spine are involved in autonomic functions and reflexes, but they do not directly trigger the bodily changes associated with the stress response like the pituitary complex does.