The adrenals are a pair of three cornered glands capping the upper end of the kidneys. (See fig. IV). Each adrenal is a double gland composed of a cortex -an outer layer and a medulla-an inner layer, making up the bulk of the gland. The amount of blood passing through the adrenals is very great compared to their size.
More than three dozen hormones are produced by these glands. A number of these are essential to life. They stimulate the healthy growth of the brain sex cells, develop mental concentration and physical endurance and generate a vigorous muscular and nervous constitution.
The functioning of the adrenal medulla is intimately linked with the sympathetic nerve action. Fear, pain, exposure to cold, low blood pressure, and emotional upsets stimulate the release of epinephrine (also called adrenaline) and norepinephrine. Through repeated excitement, anger, fear, etc., the adrenal glands may be exhausted of their reserve supply of adrenaline. Adrenal deficiency is characterized by indecision, a tendency to worry and an inclination to weep at the slightest provocation.