From the desk of Lewis S. Blevins Jr. M.D. – The adrenals are paired glands, one on each side, that are located above the kidneys in the fatty tissues of the retroperitoneal space behind the stomach, intestines, and liver.
They develop near the gonadal ridge, from which the ovaries in women and testicles in men arise. As a result, it is possible to see adrenal tissue anywhere along the locations of the primitive gonadal ridge and even in the testicles and ovaries.
There is a lot of adrenal reserve built into the system. Many people live and do well with only one adrenal gland. I remember being told that one would likely do fine with one quarter of one adrenal gland.
It is useful to think of the adrenals as having multiple functions or as several hormone systems rolled into one.
The outer part of the adrenal cortex or rind of the adrenals is called, microscopically, the zona glomerulosa and is responsible for aldosterone production. Aldosterone is a mineralocorticoid hormone that regulates salt and water as well as potassium handling by the kidneys. The renin-angiotensin-aldosterone system is complex and will be reviewed separately.
The inner part of the adrenal cortex has two main parts. The zona fasiculata and the zona reticularis. This part of the adrenal is regulated by ACTH secretion by the pituitary gland. Cortisol, a glucocorticoid hormone with a multitude of critical actions in the body, is produced in the zona fasiculata while adrenal androgens, including DHEA-S are produced in the zona reticularis. Some compounds provided by the fasiculata can be converted to androgens.
The inner part of the adrenal gland, called the medulla, is part of the autonomic sympathetic nervous system and is composed of sympathochromaffin cells that secrete epinephrine and some norepinephrine. These are neurotransmitters that regulate many body processes involved in stress responses and cardiovascular function. Cortisol is necessary for the production of epinephrine. People with no adrenal tissue still have the flight or fight responses as the rest of the autonomic nervous system takes care of many important functions.
Adrenal disorders are a wide array of conditions that can affect one or more of the different components of adrenal function. There can be either deficiencies or excesses of the various hormones. Genetic conditions can result in low levels or high levels or even a combination of low and high levels depending on the underlying condition. The adrenals can also be involved by other disease processes including autoimmune, infectious and cancerous disorders. The adrenals may be affected by benign or malignant growth processes that can cause nodules, hyperplasia, and may be associated with normal, low, or high hormone levels. The adrenals may be overstimulated by ACTH or the renin-angiotensin syndrome. Many of the hormone abnormalities associated with adrenal disorders are subtle and our goals are to promote early diagnosis and treatment. We will cover some of not all of these major classes of acquired and genetic disorders over the course of our work at Adrenal World News.
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