Answer
The adrenal glands are located superior to the kidneys in the retroperitoneal space.. Each gland is surrounded by a connective tissue capsule. Each gland (itself) comprises two different functional entities--the cortex which secretes steroid hormones, and the adrenal medulla which secretes catecholamine hormones.
Work Step by Step
The Adrenal Cortex
Histologically, the cortex is usually considered as comprising three zones -- zona glomerulosa, zona fasciculata, and zona reticularis.
The cells of the glomerulosa are arranged in small spheroid clusters and curved columns. These cells make up 15% of the cortex and they secrete the mineralocorticoid hormone aldosterone.
Cells of the zona fasciculata display as long 2-cell cords with generous amounts of cytoplasm. and lipid vacuoles. The zona fasciculata secretes glucocorticoids, mainly cortisol.
The zona reticularis is only about 10% of the volume of the cortex.
The cells are small and arranged in branching cords with few lipid vesicles. The reticularis cells secrete weak androgens like dihydrotesterone (DHT) They also secrete a small amounts of glucocorticoids.
The Adrenal Medulla :
Anatomically, and embryogenically , the adrenal medulla is really a modified sympathetic ganglion of the autonomic nervous system (ANS). The cells of the medulla lack axons, and they cluster around large blood vessels in the highly vascular tissue. However, they are innervated by preganglionic neurons of the ANS. This enables the ANS to exert direct control over adrenal medullary function and allows the chromaffin cells to respond quickly to ANS stimulation. The chromaffin cells secrete the catecholamine hormones epinephrine, and norepinephrine ( and a little dopamine). These hormones intensify sympathetic responses elsewhere in the body.
