The adrenal (suprarenal) glands consist of a cortex (secretes mineralocorticoids, glucocorticoids, and androgens) and a medulla (secretes adrenalin). The adrenal glands lie at the T12 vertebral level, on the superior pole of each kidney, and are separated from the kidneys by the renal capsule. The left adrenal gland is positioned more medially than the right adrenal gland (Figure 11-5).
Vascular supply. Each gland receives an arterial supply from three arteries: superior adrenal artery (branch of the inferior phrenic artery), middle adrenal artery (branch of the aorta), and inferior adrenal artery (branch of the renal artery). Venous drainage of the right adrenal gland empties directly into the inferior vena cava, whereas that of the left adrenal gland empties into the left renal vein. Innervation. Sympathetic nerves innervate the adrenal medulla. The least splanchnic nerve, through the aorticore-nal ganglion, provides innervation. However, unlike other organs innervated by the sympathetic nerves, only pregan-glionic neurons enter the adrenal medulla. The adrenalin (epinephrine) hormones released into the blood stream act like a systemic postganglionic neuron to stimulate tissues around the body that have receptors for adrenalin.
The adrenal cortex is primarily regulated within the endocrine system by hormones from the pituitary gland (e.g., adrenocorti-cotropic hormone).
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