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Physiology of Adrenal Medulla

Physiology of Adrenal Medulla. Hormones of the Adrenal Medulla. Adrenaline (epinephrine) Noradrenaline (norepinephrine). 80% of released catecholamines are epinephrine. Hormones are secreted and stored in the adrenal medulla and released in response to appropriate stimuli. tyrosine.

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Physiology of Adrenal Medulla

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  1. Physiology of Adrenal Medulla

  2. Hormones of the Adrenal Medulla • Adrenaline (epinephrine) • Noradrenaline (norepinephrine) • 80% of released catecholamines are epinephrine. • Hormones are secreted and stored in the adrenal medulla and released in response to appropriate stimuli.

  3. tyrosine di-hydroxyl-phenylalanine dopamine norepinephrine epinephrine Catecholamine Synthesis tyrosine hydroxylase L-aromatic amino acid decarboxylase dopamine-B-hydroxylase phenylethanolamine-N-methyltransferase

  4. Mechanism of Action • Receptor mediated – adrenergic receptors. • Peripheral effects are dependent upon the type and ratio of receptors in target tissues. Relative effects of epinephrine and norepinephrine on  and  adrenergic receptors. Guyton

  5. Differences between Epinephrine and Norepinephrine • Epinephrine >> norepinephrine – in terms of cardiac stimulation leading to greater cardiac output ( stimulation). • Epinephrine >> norepinephrine –in terms of increasing metabolism. • Epinephrine < norepinephrine – in terms of constriction of blood vessels – leading to increased peripheral resistance – increased arterial pressure.

  6. Effects of Epinephrine • Metabolism • Glycogenolysis in liver and skeletal muscle: • Mobilization of free fatty acids • Increase metabolic rate. • can lead to hyperglycemia. -Increases O2 consumption.

  7. Effects of Epinephrine • Cardiovascular • Heart rate & cardiac contractility • BP Respiration: Oxygen consumption & respiratory rate.

  8. Pheochromocytoma • A catecholamine-secreting tumor of chromaffin cells of the adrenal medulla. • adrenal pheochromocytoma (90%). • Extra-adrenal pheochromocytoma.

  9. Signs and Symptoms of Pheochromocytoma • resistant hypertension (95%) • headache • sweating • palpitations • chest pain • anxiety • glucose intolerance • increased metabolic rate classic triad

  10. Diagnosis and Treatment • High plasma catecholamine. • Increased metabolites [VMA] in urine • Treatment is surgical resection Imaging

  11. A case study? “Rollie Hendrix,” a 35-year-old husband and father of three children, has been experiencing headaches and palpitations of increasing frequency and severity over the past six months. In addition, he has had periods of intense anxiety and panic attacks.

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