Adrenal Cortex Hormones 2 PDF

# Endocrine System: The Adrenal Gland ## Adrenal Gland - Located on top of the kidneys. - Triangular shaped gland. - Consists of two parts: - **Medulla** - center of the gland - **Cortex** - outer layer ### Location and Structure - Adrenal glands are triangle-shaped glands located on t...

# Endocrine System: The Adrenal Gland ## Adrenal Gland - Located on top of the kidneys. - Triangular shaped gland. - Consists of two parts: - **Medulla** - center of the gland - **Cortex** - outer layer ### Location and Structure - Adrenal glands are triangle-shaped glands located on top of the kidneys. - 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 norepinephrine (adrenaline). ## Adrenal Gland Diagram A diagram shows the following: - Adrenal gland - Cortex - Medulla - Blood vessels - Kidney - Capsule ## Adrenal Cortex - Produces other hormones. - Cortisone and aldosterone. ### Adrenal Cortex Layers - Three areas: - Zona glomerulosa - Zona fasciculata - Zona reticularis ## Adrenal Gland Cross Section - A diagram illustrates the following: - Transverse Section - Capsule - Cortex - Medulla - Microscopic Section - Capsule - Zona Glomerulosa - Zona Fasciculata - Zona Reticularis - Medulla ## Hormones Produced by the Adrenal Cortex - **Glucocorticoid** - **Mineralocorticoids** - **Androgens** ## Adrenal Cortex Layers and Primary Products | Layer | Name | Primary product | |---|---|---| | Most superficial cortical layer | Zona glomerulosa | Mineralocorticoids (e.g aldosterone) | | Middle cortical layer | Zona fasciculata | Glucocorticoids (e.g cartisol) | | Deepest cortical layer | Zona reticularis | Weak androgens (e.g adrenosterone) | ## Corticosteroids - Hormones that are produced from the adrenal cortex. - Synthesized from enzymatic modification of cholesterol - Two categories; - Glucocorticoids - Mineralocorticoids ## Glucocorticoids - So referred because they were seen to increase the levels of plasma glucose. - Made in the fasciculata and reticularis layer near cortical medullary junction. - Cortisol is the major glucocorticoid - Cortisol deficiency can therefore result in hypoglycemia (below normal levels of blood glucose) ## Glucocorticoids Structures - **Cortisol** (Hydrocortisone) - **Corticosterone** - **Cortisone** ## Glucocorticoids Synthesis - Precursor: cholesterol - Major glucocorticoid: cortisol ## Synthesis of Hormones in Adrenal Cortex - Diagram showing pathway for synthesis of the following: - Cortisol - Aldosterone ## Major Pathways in Steroid Biosynthesis - Diagram showing the following: - Cholesterol - Pregnenolone - Progesterone - Deoxycorticosterone - Corticosterone - Cortisol - Aldosterone - 17-hydroxy pregnenolone - 17-hydroxy progesterone - Dehydroepiandrosterone - Androstenedione - Testosterone - Estrone - Estradiol ## Enzymes for Aldosterone Synthesis - **DE** = debranching enzyme; side chain cleavage enzyme; desmolase - **Deh.** = 3ẞ-hydroxysteroid dehydrogenase enzyme - **21** = 21a hydroxylase - **11** = 11 β-hydroxylase - **18** = Aldosterone synthase ## Aldosterone Biosynthesis - Synthesized in the Zona glomerulosa - ENZYMATIC MACHINERY is partly mitochondrial and partly endoplasmic. - Four Enzymes: - Cytochrome P450scc enzyme - Aldosterone synthase - 21-hydroxylase - 3ẞ-hydroxysteroid dehydrogenase ## Aldosterone Actions - Diagram showing the pathways and effects of aldosterone: - Inflammation - Oxidative Stress - Smooth Muscle Proliferation - Altered Vasoreactivity - Atheroslcerosis - Insulin Resistance - Thrombosis - Collagen Formation ## Body Fluid Compartments - About 55% of women's body weight and 60% of men's body weight are fluids - Intracellular fluid (ICF) - About 2/3 of body fluid - Extracellular fluid (ECF) - Interstitial fluid between cells is 80% of ECF - Plasma in blood is 20% of ECF ## Body Fluid Compartments Diagram - Diagram shows the following: - Total body mass of female - Total body mass of male - Total body fluid - Intracellular fluid (ICF) - Extracellular fluid (ECF) - Interstitial fluid - Tissue Cells - Blood Capillary ## Functions of Mineralocorticoids - Aldosterone exerts 90% of mineralocorticoid activity. - Cortisol also has mineralocorticoid activity, but only 1/400th that of aldosterone - Aldosterone increases renal tubular (principal cells) reabsorption of sodium & secretion of potassium. - Excess aldosterone ↑ ECF volume & arterial pressure, but has only a small effect on plasma sodium concentration ## Aldosterone Effect on Metabolism - Three Ways: - Increases urinary excretion of potassium ions. - Increases interstitial levels of sodium ions. - Increases water retention and blood volume. ## Mineralocorticoids - Synthesized in the glomerulosa. - Aldosterone is the major mineralocorticoid hormone. - Considered mineralocorticoid because it promotes salt and water retention in the kidneys. - Steroid hormones: Glucocorticoids, mineralocorticoids and sex steroids ## Disorders of the Adrenal Gland - **Hypoaldosteronism** - Results in excess loss of water/Na+. - Addison’s disease - low aldosterone & cortisol. - **Hyperaldosteronism** - **Cushing’s syndrome** - Hypersecretion of cortisol, androgens, aldosterone. ## Adrenal Glands Malfunction - **Cushing syndrome** - Hypersecretion of glucocorticoids by the adrenal cortex that is characterized by weight gain in the trunk of the body, but not arms and legs ## Cushing’s Disease - Proximal muscle wasting & weakness - Osteoporosis - Glucose intolerance - HTN, hypokalemia - Thromboembolism - Depression, Psyc - Infection - Glaucoma ## Addison’s Disease - Hyposecretion of glucocorticoids by the adrenal cortex characterized by bronzing of the skin. ## Glucocorticoid and Mineralocorticoid Hormones and their Effects - Diagram showing the effects of glucocorticoids and mineralocorticoids including: - Glucocorticoids - Inflammatory response - Immunological response - Liver glycogen deposition - Gluconeogenesis - Glucose output from liver - Glucose utilization - Protein catabolism - Bone catabolism - Mood - Gastric acid and pepsin - Na+ reabsorption - K+/H+ excretion - Mineralocorticoids - Adrenal suppression - Increased susceptibility to infection - Diabetes - Muscle wasting - Growth suppression in children - Osteoporosis - Psychosis - Peptic ulceration - Na+ and H2O retention - Hypokalemia - Hypertension - Muscle weakness ## Androgens - Produced in the zona reticularis. - Androgenic steroids are produced by the zona reticularis layer of the adrenal cortex. - Testosterone is a male sex hormone. - Assist the development of male characteristics and proper development of male sex organs during embryonic development. ## Plasma Concentrations and Secretion Rates of Adrenocortical Hormones | Hormone | 8 A.M. Plasma concentration (µg/dl) | Secretion Rate (mg/day) | Half-life (minutes)| |---|---|---|---| |Cortisol | 15 | 15 | 100 | | Corticosterone | 1 | 3 | 30 | | Deoxycocticosterone | 0.07 | 0.6 | 40 | |Aldosterone | 0.12 | 0.15 | 15 | |DHEA | 0.5 | 4* | <20 | |DHEAS | 150 | 15* | 1,200 | |Androstenedione | 0.12 | 1.5* | <20 | **Note:** - DHEA = dehydroepiandrosterone - DHEAS = dehydroepiandrosterone sulfate - *About 30% originates in the gonads. ## Effects of Stress and The Adrenal Glands - Diagram showing the effects of stress on the adrenal glands. - **Short-term stress response:** - Glycogen - glucose - ↑ Blood glucose - ↑ Blood pressure - ↑ Breathing rate - ↑ Metabolic rate - Change in blood flow patterns - **Long-term stress response:** - Sodium ions and water by kidneys - ↑ Blood volume - ↑ Blood pressure - Conversion of proteins and fats to glucose - Immune system suppressed ## Mineralocorticoid Deficiency - **Congenital** - **Acquired** ### Causes of Mineralocorticoid Deficiency - Addison’s disease - Adrenal hypoplasia - Congenital adrenal hyperplasia (21-hydroxylase and 5-hydroxysteroid dehydrogenase deficiencies) - Pseudohypoaldosteronism types I and II - Hyporeninmic hypoaldosteronism - Aldosterone biosynthetic defects - Drug induced