14.1 - Hormones of adrenal cortex – mineralcorticoids and adrenal androgens. Abnormalities of adrenocortical secretion.

sections

mineralcorticoids

aldosterone

adrenal androgens

abnormalities of adrenocortical secretion

overproduction of androgen

overproduction of aldo sterone

addisons disease

cushings disease

mineralcorticoids

• Mineralocorticoids – secreted from zona glomerulosa are a class of corticosteroid hormones of the adrenal cortex

• Involved in homeostasis of water, sodium ions (Na), and potassium ions (K+).

• Lipophilic hormones

• The mineralocorticoid- Aldosterone acts on certain cells in the kidneys to increase their reabsorption of sodium ions from the urine.

• Are involved in the regulation of electrolyte and fluid balance

• principal mineralocorticoid is aldosterone.

• Aldosterone acts on kidneys to provide active reabsorption of na+ ions and passive reabsorption of water, as well as active secretion of K+ ions.

• Water follows sodium

• This occurs in response to fluid and electrolyte deficiency in the blood

• causes an increase in blood pressure and blood volume

• aldosterone is Stimulated by angiotensin II, increased plasma Potassium, or fall in plasma Sodium. Inhibited by ANP and BN

aldosterone

Aldosterone activates mineralocorticoid receptors which usually have a high affinity for cortisol. Consequently by intracellular mechanisms- cortisol is converted to cortisone so that aldosterone can now bind to the receptor, therefore stimulating expression of SGK hormone enzyme. An enzyme that blocks the removal of the Na+/K+ pump. This facilitaes Na+ influx and k+ efflux.

adrenal androgens

• secreted by cells of the adrenal cortex-zona reticularis

• DHEA- dihydroepiandosterone

• Androstenedione—promotes metabolism and protein anabolism ad growth

• Male sex hormones. They stimulate / control the maintenance and development of male characteristics

• Testosterone is an androgen– needed for sperm production- testosterone made in testes not the adrenal cortex

• Although androgens are described as male sex hormones, both males and females have them at varying levels.

• levels increase during early 20- puberty, gradually fall during old age

• Involved in testes formation, male aggression, development of muscle tone and mass.

• In females, androgens contribute to sex drive (libido).

abnormalities of adrenocortical secretion

The adrenal glands can become either overactive or underactive.

• Cushing's syndrome and Addison's disease

1. Cushing’s syndrome -overactive adrenal glands from excessive production of cortisol.

   • Muscle weakness

   • Obesity

   • high blood pressure,

   • moon face

2. Addisons disease-low level of cortisol production from adrenal cortex

   • low blood pressure

   • fatigue

   • weight loss

   • hypoglycemia

overproduction of androgen

is rare but may result in excessive hair growth and menstrual period disturbances.

overproduction of aldosterone

leads to hyperaldosteronism and cause high blood pressure

addisons disease

cushings disease