A client has been taught relaxation exercises before beginning a painful procedure. What chemicals are believed to be released in the body during relaxation to relieve pain

When a person experiences pain or stress, the amygdala, which is part of the limbic system of the brain, processes the event, so that the body could create an emotional response. The amygdala then sends a distress signal to the hypothalamus in the brain. The hypothalamus acts as the command center of the body. It communicates with the body by sending signals through the nervous system, so the appropriate action could be performed by the person, whether it is a fight or flight response. The hypothalamus then activates the sympathetic nervous system, specifically the autonomic nervous system, and then the adrenal glands. The adrenal glands then release epinephrine (commonly known as adrenaline), which is a hormone, into the bloodstream. The hormone circulates throughout the body through the bloodstream, and into various organs, where it exhibits certain physiologic changes. Due to adrenaline, the strength and pain threshold of the body increases, which allows the body to tolerate more pain in instances of stress or fear.