Monday, April 5, 2010

Adrenal Glands

The adrenal glands are orange-colored endocrine glands which are situated on top of the kidneys. They are triangle-shaped, measuring about one-half inch in height and 3 inches in length.

The adrenal gland is composed of two parts: 1) the cortex, which secretes steroid hormones such as cortisol, aldosterone, and testosterone; 2) the medulla, which is the inner part that produces epinephrine and norepinephrine, which are commonly called adrenaline and noradrenaline respectively. When the glands produce more or less hormones than your body needs, you can become sick.

The cortex of the adrenal gland is devoted to the synthesis of corticosteroid hormones from cholesterol. Some cells belong to the hypothalamic-pituitary-adrenal axis and are the source of cortisol and corticosterone synthesis. Under normal unstressed conditions, the human adrenal glands produce the equivalent of 35 to 40 mg of cortisone acetate per day. Other cortical cells produce androgens such as testosterone, while some regulate water and electrolyte concentrations by secreting aldosterone. In contrast to the direct innervation of the medulla, the cortex is regulated by neuroendocrine hormones secreted by the pituitary gland and hypothalamus, as well as by the renin-angiotensin system.

Adrenal Glands Animation