Adrenal hormone

Adrenal hormone

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  Suprarenal Glands • Dividedinto two parts; each with separate functions • Suprarenal Cortex • Suprarenal Medulla ADRENAL GLAND HORMONES The Adrenal Gland The adrenal system vitally important for the survival of stress Preparation for flight or fight
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  The Adrenal Glands •Adrenal medulla • Adrenal cortex Three specific zones and each produces a specific class of steroid hormone Zona glomerulosa – mineralocorticoids (Aldosterone) Zona fasciculata – glucocorticoids ( Cortisole ) Zona reticularis - androgens
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  Steroid biosynthesis: 3main pathways “corticoid” = ..from the cortex “minerals” = Na+, K+,.. “gluco..” = increases sugar “andros” = male “gen..”= generate Mineralocorticoid Pathway Glucocorticoid Pathway Androgen Pathway Steroid biosynthesis: The 3 main pathways.
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  Biosynthetic pathway of Adrenalcortex hormones:
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  Mineralocorticoids • Aldosterone exertsthe 90% of the mineralocorticoid activity. Cortisol also have mineralocorticoid activity, but only 1/400th that of aldosterone. • Aldosterone increases renal tubular (principal cells) reabsorption of sodium & secretion of potassium • Aldosterone stimulates sodium & potassium transport in sweat glands, salivary glands, & intestinal epithelial cells Action s of aldost erone Regulation of aldosterone secretion
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  Renin-Angiotension-Aldosterone System Modeof Action of Aldosterone Associated Clinical Conditions Hyperaldosteronism: The overproduction of aldosterone by the adrenal glands Leads to arterial hypertension (high blood pressure) associated with hypokalemia, usually a diagnostic clue. Conn’s syndrome is primary hyperaldosteronism caused by an aldosterone-producing adenoma. Hypoaldosteronism: This condition may result in hyperkalemia. It can also cause urinary sodium wasting, leading to volume depletion and hypotension.
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  Hormones of theAdrenal Cortex (Glucocorticoids)  Glucocorticoids (including cortisone and cortisol)  Produced in the middle layer of the adrenal cortex  Promote normal cell metabolism  Help resist long-term stressors  Released in response to increased blood levels of ACTH Effect of cortisol on protein metabolism • Reduction of protein storage in all cells except those of liver – ↑ protein catabolism & ↓ protein synthesis • Cortisol increases liver & plasma proteins • Mobilizes aminoacids from non hepatic cells, thus increase blood amino acid level. • ↑ amino acid transport to liver cells & ↓ transport of amino acids into other cells Functions of glucocorticoids REGULATION OF CORTISOL SECRETION
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  Hormones of theAdrenal Cortex  Sex hormones  Produced in the inner layer of the adrenal cortex  Androgens (male) and some estrogen (female)  stimulates or controls the development and maintenance of male characteristics in vertebrates by binding to androgen receptors. Androgens Different class of Androgens  Dihydroepiandrosterone (DHEA)  Androstenediol  Androstenedione  Dyhydrotestosterone Functions of Androgen Hormones  Testes formation Androgens regulates certain Y chromosome genes, particularly SRY, control development of the male phenotype, including conversion of the early bipotential gonad into testes.  Androgen effects: Acts as paracrine hormone required by the Sertoli cells in order to support sperm production During puberty, they stimulate the germ cells to differentiate into sperm.  Spermatogenesis  Inhibition of fat deposition  Increase muscle mass
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  Hormones of theAdrenal Medulla  Produces two similar hormones (catecholamines)  Epinephrine  Norepinephrine  These hormones prepare the body to deal with short-term stress Biosynthesis of catecholamines A catecholamine (CA) is has a catechol (benzene with two hydroxyl side groups) and a side-chain amine. They have a half-life of a few minutes when circulating in the blood. They can be degraded either by methylation by catechol-O- methyltransferases (COMT) or by deamination by monoamine oxidases (MAO). Features of Catecholamines Two catecholamines, norepinephrine and dopamine, act as neuromodulator in the CNS and as hormones in the blood circulation. High catecholamine levels in blood are associated with stress, which can be induced from psychological reactions or environmental stressors such as elevated sound levels, intense light, or low blood sugar level.
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  Effects of Catecholamine Catecholaminescause general physiological changes that prepare the body for physical activity (fight-or-flight). Some typical effects are increases in heart rate, blood pressure, blood glucose levels, and a general reaction of the sympathetic nervous system. Action of Epinephrine on a Liver Cell 1. Epinephrine is lipophobic and needs to bind to specific receptor proteins on cell surface. 2. Acting through intermediary G proteins the hormone bound receptor activates the enzyme adenenylyl cyclase which converts ATP to cAMP 3. Cyclic AMP performs as a 2ndary messenger and activates protein kinase-A an enzyme that was previously inactive 4. Protein kinase–A phosphorylates and activates the enzyme phosphorylase which catalyses the hydrolysis of glycogen into glucose.
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  IP3/CA++ Second-Messenger System 1.The hormone epinephrine binds to specific receptor proteins on the cell surface. 2. Acting through G- proteins, the hormone-bound receptor activates the enzyme phospholipase C, which converts membrane phospholipids into inositol triphosphate (IP3) 3. IP3 diffuses through the cytoplasm and binds to receptors on the endoplasmic reticulum 4. The binding of IP3 to the receptor stimulates the endoplasmic reticulum to release Ca++ into the cytoplasm 5. Some of the released Ca++ binds to the receptor protein called calmodulin 6. The Ca++/Calmodulin complex activates other intracellular proteins – producing the horomone effects Disorders of the Adrenal Gland 1. Hypoaldosteronism loss of water/Na+ Addison’s disease – low aldosterone & cortisol 2. Hyperaldosteronism 3. Cushing’s syndrome Hyper secretion of cortisol, androgens, aldosterone
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  Cushing’s syndrome Cushing's syndromeassociated with prolonged exposure to inappropriately high levels of the hormone cortisol. This can be caused by taking glucocorticoid drugs, or diseases that result in excess cortisol, ACTH, or CRH levels. Cause: Most common cause of Cushing's syndrome is exogenous administration of glucocorticoids prescribed by a health care practitioner to treat other diseases. Effect of steroid treatment of a variety of disorders such as asthma and rheumatoid arthritis, or in immunosuppression after an organ transplant. Signs and symptoms Rapid weight gain, particularly of the trunk and face with sparing of the limbs (central obesity). Growth of fat pads along the collar bone and on the back of the neck (buffalo hump) and a round face often referred to as a “moon face.” Thinning of the skin (which causes easy bruising and dryness, particularly the hands) Hyperhydrosis (excess sweating), Telangiectasia (dilation of capillaries),