The brain is an incredibly complex organ that controls almost every aspect of daily life, from involuntary actions like breathing or yawning to voluntary tasks like walking or solving math problems. While the brain is the body’s intellectual powerhouse, it is also very fragile and is affected by its environment. The body’s external environment can influence the brain as much as its internal environment. These influences can produce a multitude of reactions within the brain that then cascade through the body; reactions can be positive, negative, or neutral.
- When the body faces a stressor of some form, the first place to react is the amygdala, which is often called the ‘fear of the amygdala is a little more complex than that, one of its main responsibilities is to experience emotions like anger, happiness, fear, or stress. The amygdala will send a distress signal to the hypothalamus, the part of the brain responsible for managing hormones, influencing the nervous system, and maintaining homeostasis in the body.
- The hypothalamus will trigger the pituitary gland to release a flood of Adrenocorticotropic hormone (ACTH) into the body. ACTH is important for regulating the amount of cortisol, or stress hormone, released into the body by the adrenal gland. ACTH travels to the adrenal glands, which are found above the kidneys.
- The adrenal glands then release adrenaline and cortisol into the bloodstream. Both adrenaline and cortisol are ‘stress hormones’ that cause physical manifestations of stress.
- Physical manifestations include things like sweating, increased heart rate, faster breathing, increased blood pressure, and more. These reactions are also known as the ‘fight or flight’ response, which were evolutionarily designed to combat environmental stressors by either running away or fighting.
Physiology Tip:
Once the stressor has been dealt with or the body is no longer in a stressful situation, the same pathway of organs and hormones will be involved in deactivation. The amygdala will stop signaling to the hypothalamus, which will in turn stop the pituitary gland from releasing ACTH. Without this hormone present in the body, the adrenal gland will lessen the amount of cortisol and adrenaline released into the blood stream.