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After studying this chapter, you should be able to:

  • Name the three catecholamines secreted by the adrenal medulla and summarize their biosynthesis, metabolism, and function.

  • List the stimuli that increase adrenal medullary secretion.

  • Differentiate between C18, C19, and C21 steroids and give examples of each.

  • Outline the steps involved in steroid biosynthesis in the adrenal cortex.

  • Name the plasma proteins that bind adrenocortical steroids and discuss their physiologic role.

  • Name the major site of adrenocortical hormone metabolism and the principal metabolites produced from glucocorticoids, adrenal androgens, and aldosterone.

  • Describe the mechanisms by which glucocorticoids and aldosterone produce changes in cellular function.

  • Define the physiological and pharmacological effects of glucocorticoids.

  • Contrast the physiological and pathological effects of adrenal androgens.

  • Describe the mechanisms that regulate secretion of glucocorticoids and adrenal sex hormones.

  • Explain the actions of aldosterone and describe the mechanisms that regulate aldosterone secretion.

  • Describe the main features of the diseases caused by an excess or deficiency of each of the hormones of the adrenal gland.


The adrenal glands are endocrine organs that produce several hormones including catecholamines and steroid hormones. There are two adrenal glands, one sitting on top of each kidney (Figure 19–1). Each adrenal gland has an outer cortex that secretes the steroid hormones, mineralocorticoids, glucocorticoids and androgens, and an inner medulla that secretes the catecholamines, epinephrine, norepinephrine, and dopamine.


Human adrenal glands. Adrenocortical tissue is yellow; adrenal medullary tissue is blue. Note the location of the adrenals at the superior pole of each kidney. Also shown are extra-adrenal sites (gray) at which cortical and medullary tissue is sometimes found. (Reproduced with permission from Williams RH: Textbook of Endocrinology, 4th ed. St. Louis, MO: Saunders; 1968.)

The adrenal cortex secretes glucocorticoids (eg, cortisol) which are steroids with widespread effects on the metabolism of carbohydrate and protein; and a mineralocorticoid (aldosterone) essential to the maintenance of Na+ balance and extracellular fluid (ECF) volume.Mineralocorticoids and the glucocorticoids are necessary for survival. It is also a secondary site of androgen synthesis, secreting sex hormones such as testosterone, which can exert effects on reproductive function. Adrenocortical secretion is controlled primarily by adrenocorticotropic hormone (ACTH), from the anterior pituitary (Chapter 20), but mineralocorticoid secretion is also subject to independent control by circulating factors, of which the most important is angiotensin II, a peptide formed in the bloodstream by the action of renin.

The adrenal medulla is in effect a sympathetic ganglion in which the postganglionic neurons have lost their axons and become secretory cells. The cells secrete when stimulated by the preganglionic nerve fibers that reach the gland via the splanchnic nerves. Adrenal medullary hormones (epinephrine, norepinephrine, and dopamine) work mostly to prepare the body for emergencies, ...

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