The adrenaline glands are members of the endocrine system, normally existing in pairs in human beings and are physically situated on top of the kidneys. As vital components of the endocrine system, they play a chief role in the production of the hormones such as cortisol, epinephrine, and aldosterone, directly secreting these compounds into the bloodstream to influence internal changes in the body in order to adapt to certain sources of stimuli. The adrenal glands receive stimulation for hormone production from the nervous system, principally controlled by nerve signals originating from the hypothalamus which are then transported to the pituitary gland.

The adrenal glands are naturally present in pairs in the human body, located superiorly to the kidneys. With reference to the vertebral column, they can be more specifically found at the same height of the 12th vertebra of the spine. Individually, the adrenal glands are each made up of an outer capsule and an inner core, which are the adrenal cortex and the medulla respectively. Each section is responsible for the production of hormones that influence the operations of the body in their own distinct ways. The adrenal cortex is tasked with the production of cortisol, aldosterone, and the androgens; which are released with the purpose of responding to stress (cortisol and aldosterone) or in order to develop and maintain the secondary sexual characteristics (androgen). The medulla on the other hand produces epinephrine and norepinephrine which are secreted to trigger the fight-or-flight response in a human being, augmenting a person’s responses to threats, raising the person’s heart rate, constricting blood vessels, and widening air passages in order to better tolerate increased effort and improve mobility. In addition to its main functions, the adrenal glands also secrete the hormone aldosterone which facilitates the retention of sodium and water in the renal system.