Stress or sensory information comes from our environment into our brain from our sight, smell, sound, touch, and taste. The amygdala is responsible decide if any stress or sensory information is dangerous or harmful. The limbic system is the hypothalamus control center to evaluate neurochemicals to perceptions of fear, anger, disgust, sadness, happiness and surprise. When the brain perceptions trigger the amygdala, the autonomic nervous system initiates survival of necessary organs to fight, flee, freeze, or fawn. The kidneys use renin, angiotensin, erythropoietin, iron, and antidiuretic hormone to maintain fluid and temperature balance in the blood vessels, heart, respiratory system, and lymph system. The pancreas uses glucagon and insulin to regulate glucose as the main source of energy for fight or flight as well as growth and development. The pineal gland uses melatonin and serotonin for regulation of sleep and cognition as well as alertness as awareness in fight or flight. The thyroid and parathyroid regulate all organ systems required for homeostasis of bodily functions at rest and for survival
