The Adrenal Gland is a part of the Endocrine system that produces hormones in the fluid surrounding the secretory cells. The Endocrine system is made up of the Pituitary, Thyroid, Parathyroid, Pineal and the Adrenal glands, but there are also different organs and tissues that possess the functions of the different glands of the Endocrine system, some of them are the liver, skin, small intestine, heart, pancreas, ovaries, kidneys, testes, stomach, adipose tissue, hypothalamus, thymus and the placenta. Hormones are important because they normalize the different cells in the body, thus producing the normal functioning of the body.
The Adrenal glands are also called as Suprarenal Glands because they lie above the kidneys and has a trodden pyramidal figure. "In adults, each adrenal gland is about 3-5 cm in height and 2-3 cm in width, and a little less than 1 cm thick",as stated in book of authors Gerard J. Tortora and Sandra Reynolds Grabowski, Principles of Anatomy and Physiology 10th ed. The adrenal glands are separated into two useful parts; the adrenal cortex which is located at the edge or the margin of the adrenal gland, and the adrenal medulla which is found at the interior part of the gland. Like most glands, the adrenal gland is also rich in blood vessels.
The Adrenal Cortex is divided into regions/zones that secrete their own hormone that have their own essential function. The outmost region is the zona glomerulosa it is located below the connective tissue covering, it has cells that are set in round huddles and domed columns that produce hormones called Mineralocorticoids that influences mineral hemostasis. The spacious of the three zones is the zona fasciculata; it is located at the center of the adrenal cortex and has cells arranged in long, straight columns that produce the hormone glucocorticoid responsible in glucose hemostasis. The innermost of the zone, zona reticularis has cells arranged in bough strings; these produce minute quantity of feeble androgens that have muscularizing end products.
The Adrenal Medulla on the other hand is a modified sympathetic ganglion of the autonomic nervous system (Tortora et.al), it also secretes hormones through the chromaffin cells, epinephrine and norepinephrine are the two hormones produced by the chromaffin cells of the adrenal medulla, and they act on the autonomic nervous system during cases of stress.
Like other glands of the body, the adrenal gland is important for it aids in the normal functioning of some parts of the body, that when the supply of hormones are insufficient could be fatal to the person. Bottom line is, the Adrenal glands are not so famous as other organs are, but the adrenal glands are also one of the most important parts that we have to consider.
Gerard J. Tortora and Sandra Reynolds Grabowski, Principles of Anatomy and Physiology 10th edition