MBS TEST

• Aldosterone


  Hormone secreted from Zona glomerulosa of adrenal cortex
• Mineralocorticoids


  • Affect mineral homeostasis
• Aldosterone


  Increases rate of sodium reabsorption by kidneys increasing sodium blood levels
• Glucocorticoids


  • Affect glucose homeostasis
• Cortisol

  Major glucocorticoid hormone (95%) secreted from Zona fasciculata
• Cortisol

  Increases fat and protein breakdown, increases glucose synthesis, decreases inflammatory response
• Androgens


  • Have masculinizing effects
• Dehydroepiandrosterone (DHEA)


  Only important androgen in females, converted to androgen and testosterone
• Aldosterone


  Transported in blood loosely bound to albumin and transcortin
• Actions of aldosterone


  1. Promotes Na+ absorption in exchange for K+ and H+ at collecting ducts of nephron

  2. Promotes Na+ reabsorption in epithelial cells of sweat glands, salivary and gastrointestinal mucosa

  3. Increases K+ excretion in sweat and saliva

  4. Stimulates Mg2+ excretion by kidney
• Aldosterone


  Maintains extracellular fluid concentration of sodium and extracellular fluid volume
• Regulators of aldosterone secretion

  • Plasma K+ concentration (most important)
  • Angiotensin II (principal regulator)
• Hyperkalemia (higher-than-normal levels of potassium in bloodstream) acts directly on zona glomerulosa to stimulate aldosterone secretion
• Excess secretion of aldosterone (Conn's syndrome) results in high blood pressure and low potassium levels
• Regulation of cortisol secretion

  1. Hypothalamus secretes CRH

  2. CRH stimulates pituitary to release ACTH

  3. ACTH prompts adrenal glands to release cortisol

  4. Cortisol inhibits release of CRH and ACTH through negative feedback
• Importance of cortisol


  • Stress response
  • Metabolism regulation
  • Maintaining blood pressure
• Metabolic effects of cortisol

  • Glucose sparing effect
  • Lipid catabolism
  • Oxidation of lipids for energy
  • Increases glucose
  • Protein catabolism
  • Gluconeogenesis in liver
• Cortisol in stressful situations

  • Glucose sparing effect
  • Lipid oxidation
  • Gluconeogenesis
  • Anti-inflammatory effects
  • Suppresses immune system
• Overproduction of cortisol (Cushing's syndrome) is caused by a benign pituitary tumor that leads to excess ACTH secretion
• Androgens


  Androstenedione and DHEA secreted from Zona reticularis
• Overproduction of androgens


  Causes abnormal growth and masculinization in both sexes
• Cholesterol is the precursor of steroid hormones
• 21-α-hydroxylase and 11-β-hydroxylase enzyme deficiencies result in decreased cortisol and aldosterone and increased testosterone synthesis
• In the case study, the woman has elevated androstenedione, DHEA-S, and 17α-hydroxyprogesterone levels, indicating a congenital adrenal hyperplasia disorder
• The case study woman has symptoms of Cushing's syndrome, including truncal obesity, hirsutism, virilism, hypertension, and low potassium levels
• The case study woman has an adrenal gland mass, likely causing the excess androgen production