ADRENAL GLANDS

A pair of endocrine glands, located above the kidneys, which secrete hormones that control emotional reactions and basic life processes such as metabolism, blood pressure, and sexual development. The adrenal cortex, or outer layer, of each gland is essential to life. It secretes at least thirty different hormones collectively known as cortin. Three of them are especially active: cortisol, a close relative of cortisone, is a primary regulator of carbohydrate metabolism and liver function; aldosterone governs the sodium level, water balance, and kidney functions of the body; and corticosterone is a participant in all these mechanisms. Complete destruction or removal of the cortex leads to increasing weakness, loss of appetite and gradual death, although life can sometimes be prolonged by administering large quantities of salt. An undersecretion of cortin results in Addison’s disease, which is characterized by low basal metabolism, reduced temperature and blood pressure, darkening of the skin, headaches, lassitude, and sexual inadequacy. On the other hand, a tumor or abnormal growth of the cortex sometimes leads to excessive secretion, and may produce a rare condition known as Cushing’s syndrome. Typical symptoms of this disorder, which usually occurs in young women, are muscle weakness, excessive fatigue, reduced sex drive, headaches, skin disfigurement, spinal deformity, and obesity. The cortex also produces the adrenal androgens and estrogens—male and female sex hormones which work with gonadal secretions in regulating such secondary sex characteristics as change of voice and pubic hair. An oversupply of androgens in the male may produce accelerated puberty in young boys (pu- bertas praecox), as well as a heavy beard and unusually deep voice. Similar changes may occur in the female (virilism). An undersecretion of androgens delays sexual maturity and may lead to feminine characteristics in the male, a condition known as feminism. An oversecretion of estrogens in the male may also bring about this condition. The adrenal medulla, the inner core of the gland, secretes two similar hormones, epinephrine (adrenalin) and norepinephrine (noradrenalin). These are known as catechol amines, and are derived from phenylalanine, an amino acid which also metabolizes into thyroxin and phenylpyruvic acid. When these hormones are secreted into the bloodstream, they produce the physical changes associated with strong emotions such as anger and aggressiveness—that is, they release sugar into the bloodstream, increase the pulse rate, enlarge the air passages into the lungs, widen the pupils of the eye, and raise the blood pressure. The combined effect of these changes is to mobilize energy and prepare the organism to meet an emergency. If the individual remains under stress for prolonged periods, and the physical changes persist, they may result in psychophysiologic (psychosomatic) disorders such as gastric ulcer, colitis, or hypertension.