Adrenal glands
The adrenal glands (also known as suprarenal glands) are endocrine glands that sit at the top of the kidneys; in humans, the right adrenal gland is triangular shaped, while the left adrenal gland is semilunar shaped. They are chiefly responsible for releasing hormones in response to stress through the synthesis of corticosteroids such as cortisol and catecholamines such as epinephrine (adrenaline) and norepinephrine. They also produce androgens. The adrenal glands affect kidney function through the secretion of aldosterone, a hormone involved in regulating the osmolarity of blood plasma.
An image of Adrenal glands
Either of two secretory organs patched atop the kidneys.
Each consist of two parts having independent functions:the cortex and medulla.
The cortex is can be differentiated into three structures based on structural and anatomic characteristics.
Zona glomerulosa-The outermost layer of adrenal gland,
Zona fasciculata-the middle zone.Situated between the glomerulosa and reticularis,
Zona reticularis-The inner most cortical layer.
The adrenal medulla is the core of the adrenal gland, and is surrounded by the adrenal cortex. It secretes approximately 20% noradrenaline (norepinephrine) and 80% adrenaline (epinephrine)
The adrenal cortex,in response to adrenocorticotropic hormone secreted by anterior pituitary,secretes cortisol and androgens.
Adrenal androgens serves as a precursors that are converted by the liver to testosterone and estrogens.Renin from the kidney controls adrenal cortical production of aldosterone The adrenal medulla manufactures the catecholamines epinephrine and norepinephrine.
Associated Diseases of Adrenal glands
Several adrenal tumors cause symptoms because they result in the over- or underproduction of certain hormones by the adrenal gland.
In hyperaldosteronism the glands produce too much aldosterone.
In pheochromocytoma the glands secretes excessive amounts of catecholamines.
In endogenous Cushing’s syndrome the adrenal glands produce too much cortisol.
Adrenal insufficiency denotes a group of diseases characterized by underproduction of cortisol or aldosterone. They can be caused by problems in the glands themselves, or by impairment of the pituitary gland or hypothalamus. The ACTH stimulation test may assist in diagnosis.
Addison’s disease is a rare disorder in which the adrenal glands do not produce sufficient amounts of glucocorticoids (mainly cortisol). This can be caused by an autoimmune reaction, by certain infections or by some other rarer causes.
Congenital adrenal hyperplasias are genetic defects of enzymes involved in cortisol production and can affect sex characteristics of affected patients.
Waterhouse–Friderichsen syndrome is adrenal gland failure due to bleeding into the glands, caused by severe bacterial infection.
Isolated hypoaldosteronism can rarely occur due to aldosterone synthase deficiency
Absent adrenal gland, rare congenital condition