Adrenal cortex aldosterone-producing

Aldosterone A hormone produced in and secreted by the zona glomerulosa of the adrenal cortex. Aldosterone acts on the kidneys to reabsorb sodium and excrete potassium. It is also a part of the renin-angiotensin-aldosterone system, which regulates blood pressure and blood volume. 

I. Replacement therapy. The adrenal cortex (AC) produces the glucocorticoid cortisol (hydrocortisone) and the mine-ralocorticoid aldosterone. Both steroid hormones are vitally important in adaptation responses to stress situations, such as disease, trauma, or surgery. Cortisol secretion is stimulated by hypophyseal ACTH, aldosterone secretion by angiotensin 11 in particular (p. 124). In AC failure (primary AC insuffiency ... 

The adrenal cortex (AC) produces the glucocorticoid cortisol (hydrocortisone) in the zona fasciculata and the mineralocorticoid aldosterone in the zona glomerulosa. Both steroid hormones are vitally important in adaptation responses to stress situations, such as disease, trauma, or surgery. Cortisol secretion is stimulated by hypophyseal ACTH aldosterone secretion by angiotensin II in particular (p. 128). In AC failure (primary adrenocortical insuf ciency, Addison disease), both cortisol and aldosterone must be replaced when ACTH production is deficient (secondary adrenocortical insuf ciency), cortisol alone needs to be replaced. Cortisol is effective when given orally (30 mg/day, 2/3 a.m 1 /3 p.m.). In stress situations, the dose is raised 5- to 10-fold. Aldosterone is poorly effective via the oral route instead, the mineralocorticoid fludrocortisone (0.1 mg/day) is given. 

Failure of the adrenal cortex to produce cortisol and aldosterone may be due to autoimmune or Infiltrative diseases. 

Hyperplasia or tumors of the adrenal cortex that produce excess aldosterone result in a condition known as primary aldosteronism, which is characterized by enhanced sodium and water retention, resulting in hypertension. 

In the presence of renin, an enzyme produced by specialized cells in the kidney, angiotensinogen is split to form angiotensin I. This prohormone is then acted upon by angiotensin-converting enzyme (ACE) as the blood passes through the lungs to form Ag II. Angiotensin II acts directly on the adrenal cortex to promote aldosterone secretion. 

Angiotensin II has two effects first, as a vasoconstrictor acting via receptors on vascular smooth muscle cells, and second, it stimulates the adrenal cortex gland to produce aldosterone (a mineralocorticoid steroid hormone, see Chapter 4). Aldosterone promotes the reabsorption of sodium from the renal tubule into the bloodstream and the resulting increase in osmolality (osmotic potential) of the blood causes water reabsorption in the nephrons. The outcome is an increase in blood volume and, therefore, pressure which inhibits (by negative feedback) further renin secretion from the JGA. 

Glucocorticoids and mineralocorticoids are uniquely produced by the adrenal cortex, and are collectively termed corticosteroids. Apart from aldosterone, glucocorticoid secretion is regulated by the pituitary hormone, corticotrophin. The principal corticosteroids synthesized in the body are illustrated in Figure 1.6. Glucocorticoids generally exhibit weak mineralocorticoid actions and vice versa. 

Aldosterone, produced by the adrenal cortex, acts at epithelial cells in the distal tubule of the nephron to increase the reabsorption of sodium and is therefore con-... 

The mammalian adrenal cortex is divided into three concentric zones the zona glomerulosa, zona fascicu-lata, and zona reticularis. The zona glomerulosa produces hormones, such as aldosterone, that are responsi-... 

The rate of aldosterone secretion is subject to several influences. ACTH produces a moderate stimulation of its release, but this effect is not sustained for more than a few days in the normal individual. Although aldosterone is no less than one third as effective as cortisol in suppressing ACTH, the quantities of aldosterone produced by the adrenal cortex and its plasma concentrations are insufficient to participate in any significant feedback control of ACTH secretion. 

Mineralocorticoids are involved in controlling electtolyte and fluid levels.9,44 The primary mineralo-corticoid produced by the adrenal cortex is aldosterone. Aldosterone increases the reabsorption of sodium from the renal tubules. By increasing sodium reabsorption, aldosterone facilitates the reabsorption of water. Aldosterone also inhibits the renal reabsorption of potassium, thus increasing potassium excretion. Mineralocorticoid release is regulated by fluid and electrolyte levels in the body and by other hormones, such as the renin-angiotensin system. 

Mineralocorticoids are also steroid hormones that are produced by the adrenal cortex. The principal mineralocorticoid in humans is aldosterone. Aldosterone is primarily involved in maintaining fluid and electrolyte balance in the body. This hormone works on the kidneys to increase sodium and water reabsorption and potassium excretion. 

The two principal groups of adrenal steroids are the glucocorticoids and mineralocorticoids. These hormones are synthesized from cholesterol within cells of the adrenal cortex. The primary glucocorticoid produced in humans is cortisol (hydrocortisone), and the primary mineralocorticoid is aldosterone. Glucocorticoids exert a number of effects such as regulation of glucose metabolism, attenuation of the inflammatory response, and suppression of the immune system. Mineralocorticoids are involved primarily in the control of fluid and electrolyte balance. 

Adrenocorticosteroids The group of steroid hormones produced by the adrenal cortex. These drugs include the glucocorticoids (cortisol, cortisone), min-eralocorticoids (aldosterone), and sex hormones (androgens, estrogens, progestins). 

Steroid hormones are produced in the adrenal cortex and the sex glands. All such hormones originate from cholesterol. Figure 16.4 shows the overall scheme for steroid hormone biosynthesis that is applicable to all tissues. The final products may be divided into the following groups mineralocorticoids (e.g., aldosterone), produced by the zona glomerulosa of the adrenal cortex glucocorticoids (e.g., cortisol), produced by the zona fasciculata of the adrenal cortex and the... 

The mineralocorticoid aldosterone is also produced by the adrenal cortex and promotes retention of H20 and Na+ and loss of K+ by the kidney. Cortisol is also an agonist of the aldosterone receptor but the level of cortisol is kept low by type 2 11 (Thydroxysteroid dehydrogenase, which converts cortisol to the inactive cortisone (11-dehydrocortisol). Accordingly inhibition of this enzyme by 18(i>-glycyrrhetinic acid (from liquorice) elevates cortisol with consequent effects of H20 and Na+ retention, oedema and hypertension. Further potential sites of interference by plant substances with steroid hormone metabolism include enzymes involved in steroid hormone synthesis such as the cytochrome P450-linked 11 -hydroxylase that catalyses the last step of corticosterone synthesis. 

Aldosterone a hormone produced by the adrenal cortex which is involved in the regulation of sodium and potassium in the blood. 

Angiotensin an oligopeptide which is produced from angiotensinogen (which in turn is made in the liver). It can cause the blood vessels to contract, leading to an increase in blood pressure. It also initiates the release of aldosterone from the adrenal cortex. 

Cortisol and aldosterone produced rn the adrenal cortex have a major role in physiology and pharmacology. 

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