The adrenal glands are triangular shaped hormone-producing glands situated on top of the kidneys. They measure about one-half inch in height and 3 inches in length. Structurally each gland consists of a medulla (the center of the gland), which is surrounded by the cortex.
The medulla is responsible for producing epinephrine and nor epinephrine (Adrenaline and Nor-Adrenaline)). The adrenal cortex produces cortisol (glucocorticoid) and Aldosterone. The adrenal cortex also makes sex hormones but in small amount.
Control of Secretion: Cortisol is secreted in response to a stimulating hormone called adrenocorticotropic hormone (ACTH) from the master gland ‘pituitary’ situated in the brain. ACTH is itself secreted under control of the hypothalamic peptide corticotropin-releasing hormone (CRH). Aldosterone is controlled by the body’s sodium, potassium and water concentrations.
Diseases resulting from abnormalities of this pituitary and adrenal axis either cause a deficiency status or excess status of the hormone cortisol.
Control of Cortisol Secretion
Adrenal Cortex produces Cortisol that regulates glucose, protein, and fat metabolism. It contributes towards the control of water and electrolyte concentrations.
This hormone mainly increases the glucose concentration of the blood by causing the liver to produce more glucose. It causes protein and fat breakdown to ensure that more amino acids and triglycerides are available for conversion to glucose by the liver. It tones down the inflammatory process.
The hormone aldosterone acts on the kidney to cause increased reabsorption of sodium and water with increased excretion of potassium. This helps to maintain the proper balance of these important ions. It is the main hormone that controls the electrolytes and water along with a small contribution from cortisone.
The medullary hormones are mainly responsible for the maintenance of blood pressure, heart rate, and heart function. They are responsible for the fight or flight response seen during a stressful situation. They are called Adrenaline and Nor-Adrenaline.
The adrenal gland also secretes certain amounts of Sex steroids in both men and women, this in addition to those produced by Testes and Ovaries. Certain steroid in this aspect like DHEA-S has some therapeutic consideration recently as women deficient in these can have distinct symptoms.