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Adrenocortical Hormones

Adrenocortical Hormones. Dr. Meg- angela Christi Amores. Adrenal Glands. Functional anatomy: Normal weight: 4 grams Located on the superior poles of the kidneys 2 parts: adrenal medulla adrenal cortex. Adrenal Glands. adrenal medulla the central 20 per cent of the gland

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Adrenocortical Hormones

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  1. Adrenocortical Hormones Dr. Meg-angela Christi Amores

  2. Adrenal Glands • Functional anatomy: • Normal weight: 4 grams • Located on the superior poles of the kidneys • 2 parts: • adrenal medulla • adrenal cortex

  3. Adrenal Glands • adrenal medulla • the central 20 per cent of the gland • functionally related to the sympathetic nervous system • secretes the hormones epinephrine and norepinephrine • adrenal cortex • Secretes corticosteroids • all synthesized from the steroid cholesterol

  4. Adrenocortical hormones • mineralocorticoids • they especially affect the electrolytes (the "minerals") of the extracellular fluids-sodium and potassium • Aldosteroneis the principal mineralocorticoid • Glucocorticoids • they exhibit important effects that increase blood glucose concentration • cortisol is the principal glucocorticoid. • androgenic hormones

  5. Adrenal Cortex • 3 layers: • Zonaglomerulosa • Secrete aldosterone • Zonafasciculata • Secretes cortisol and corticosterone, androgens, estrogen • Zonareticularis • secretes the adrenal androgens dehydroepiandrosterone (DHEA) and androstenedione

  6. Adrenocortical hormones • All human steroid hormones, including those produced by the adrenal cortex, are synthesized from cholesterol • Cholesterol is provided by low-density lipoproteins (LDL) in the circulating plasma • Transport of cholesterol is regulated by feedback mechanisms

  7. Adrenocortical hormones • Mineralocorticoids • Aldosterone (very potent, accounts for about 90 per cent of all mineralocorticoid activity) • Desoxycorticosterone (1/30 as potent as aldosterone, but very small quantities secreted) • Corticosterone (slight mineralocorticoid activity) • 9α-Fluorocortisol (synthetic, slightly more potent than aldosterone) • Cortisol (very slight mineralocorticoid activity, but large quantity secreted) • Cortisone (synthetic, slight mineralocorticoid activity)

  8. Adrenocortical hormones • Glucocorticoids • Cortisol (very potent, accounts for about 95 per cent of all glucocorticoid activity) • Corticosterone (provides about 4 per cent of total glucocorticoid activity, but much less potent than cortisol) • Cortisone (synthetic, almost as potent as cortisol) • Prednisone (synthetic, four times as potent as cortisol) • Methylprednisone (synthetic, five times as potent as cortisol) • Dexamethasone (synthetic, 30 times as potent as cortisol)

  9. Adrenocortical hormones • Adrenocortical Hormones Are Bound to Plasma Proteins. • 90 to 95% cortisol bound to plasma proteins: • cortisol-binding globulin or transcortin and, to a lesser extent, to albumin • slows the elimination of cortisol from the plasma • Long halflife of 60 – 90 minutes • 60% of aldosterone bound to proteins • aldosterone has a relatively short half-life of about 20 minutes • Adrenocortical Hormones Are Metabolized in the Liver

  10. Adrenocortical hormones • mineralocorticoids • they especially affect the electrolytes (the "minerals") of the extracellular fluids-sodium and potassium • Aldosteroneis the principal mineralocorticoid • Glucocorticoids • they exhibit important effects that increase blood glucose concentration • cortisol is the principal glucocorticoid. • androgenic hormones

  11. Aldosterone • Increases Renal Tubular Reabsorption of Sodium and Secretion of Potassium • net effect of excess aldosterone in the plasma is to increase the total quantity of sodium in the extracellular fluid while decreasing the potassium • lack of aldosterone secretion can cause transient loss of 10 to 20 grams of sodium in the urine a day and accumulation of potassium

  12. Aldosterone • Excess Aldosterone Causes Hypokalemia and Muscle Weakness • Excess Aldosterone Increases Tubular Hydrogen Ion Secretion, and Causes Mild Alkalosis • Too Little Aldosterone Causes Hyperkalemia and Cardiac Toxicity

  13. Regulation of Aldosterone • intertwined with the regulation of extracellular fluid electrolyte concentrations, extracellular fluid volume, blood volume, arterial pressure • almost entirely independent of the regulation of cortisol and androgens

  14. Aldosterone Regulation • Increased potassium ion concentration in the extracellular fluid greatly increasesaldosterone secretion. • Increased activity of the renin-angiotensin system (increased levels of angiotensin II) also greatly increasesaldosterone secretion. • Increased sodium ion concentration in the extracellular fluid very slightly decreasesaldosterone secretion. • ACTH from the anterior pituitary gland is necessary for aldosterone secretion but has little effect in controlling the rate of secretion

  15. Adrenocortical hormones • mineralocorticoids • they especially affect the electrolytes (the "minerals") of the extracellular fluids-sodium and potassium • Aldosteroneis the principal mineralocorticoid • Glucocorticoids • they exhibit important effects that increase blood glucose concentration • cortisol is the principal glucocorticoid. • androgenic hormones

  16. Effects of Cortisol on Carbohydrate metabolism • Stimulation of Gluconeogenesis • Decreased Glucose Utilization by Cells • Elevated Blood Glucose Concentration and "Adrenal Diabetes."

  17. Effects of Cortisol on Carbohydrate metabolism • Stimulate gluconeogenesis* • *formation of carbohydrate from proteins and some other substances • Best-known metabolic effect of cortisol • Cortisol increases the enzymes required to convert amino acids into glucose in the liver cells • Cortisol causes mobilization of amino acids from the extrahepatic tissues mainly from muscle.

  18. Effects of Cortisol on Protein Metabolism • Reduction in Cellular Protein • Cortisol Increases Liver and Plasma Proteins • Increased Blood Amino Acids, Diminished Transport of Amino Acids into Extrahepatic Cells, and Enhanced Transport into Hepatic Cells

  19. Effects of cortisol on Fat Metabolism • Mobilization of Fatty Acids • increases the concentration of free fatty acids in the plasma • helps shift the metabolic systems of the cells from utilization of glucose for energy • Obesity Caused by Excess Cortisol - buffalo-like torso and a rounded "moon face” • excess deposition of fat in the chest and head

  20. Other effects of cortisol • Important in resisting stress and inflammation • Blocks the Inflammatory Response to Allergic Reactions • Effect on Blood Cells and on Immunity in Infectious Diseases

  21. Regulation

  22. Abnormalities of Adrenocorical Secretion • Addison’s disease (hypoadrenalism) • failure of the adrenal cortices to produce adrenocortical hormones • Mineralocorticoid, Glucocorticoid deficiency • Melanin pigmentation • Cushing’s syndrome (hyperadrenalism) • Hypersecretion by the adrenal cortex causes a complex cascade of hormone effects • Mostly an excess of cortisol secretion

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