The physical symptoms of anxiety include rapid heartbeat, pounding chest, shortness of breath, rapid breathing, sweating, lump in the throat, butterflies in the stomach, nausea, vomiting, and muscle tension. These physical symptoms are due to anxiety activating a part of the brain called the amygdala, which then triggers the sympathetic nervous system and the hypothalamic-pituitary-adrenal axis (HPA axis). This then leads to the release of adrenaline into the bloodstream from the adrenal glands. This circulating adrenaline, in addition to the sympathetic nervous system activating body organs such as the heart, lungs, blood vessels, sweat glands, muscles, and skin, culminate in the above physical changes seen with anxiety. This is also known as the fight or flight stress response.
