The hypothalamus of the brain influences both portions of the adrenal gland but by different mechanisms. The adrenal cortex is essential to life, but the medulla may be removed with no life-threatening effects.
The cortex and medulla of the adrenal gland, like the anterior and posterior lobes of the pituitary, develop from different embryonic tissues and secrete different hormones. Each gland is divided into an outer cortex and an inner medulla.
The adrenal, or suprarenal, gland is paired with one gland located near the upper portion of each kidney.
