Adrenal Gland Anatomy and Physiology

The adrenals are golden yellow retroperitoneal organs, laying just superior to the kidneys (suprarenal glands) bilaterally at the level of T11-12. They’re richly vascularized organs, with two distinct components that have separate functions, the outer cortex and inner medulla. The cortex has three layers: zona glomerulosa, zona fasciculata, and zona reticularis. The zona glomerulosa produces mineralocorticoids, which play an important role in regulating blood pressure and electrolyte balance. The zona fasciculata makes glucocorticoids, which are necessary for life and modulated by the hypothalamic-pituitary-adrenal axis. Glucocorticoids regulate the immune system, blood sugar, and metabolism. The zona reticularis produces androgens and plays a role in developing secondary sexual characteristics. The innermost layer of the adrenal is the medulla, producing norepinephrine and epinephrine, which activate alpha- and beta-adrenergic receptors.