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Chapter 31 Disorders of Endocrine Function

Chapter 31 Disorders of Endocrine Function. Hypothalamus- Pituitary Axis. Releasing hormones from hypothalamus tell the pituitary what to release into the blood Trophic hormones from the pituitary tell specific peripheral glands to grow and produce their hormones. Hormone Disorders.

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Chapter 31 Disorders of Endocrine Function

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  1. Chapter 31Disorders of Endocrine Function

  2. Hypothalamus- Pituitary Axis • Releasing hormones from hypothalamus tell the pituitary what to release into the blood • Trophic hormones from the pituitary tell specific peripheral glands to grow and produce their hormones

  3. Hormone Disorders Tertiary: abnormality in stimulation from the hypothalamus Secondary: abnormality in stimulation from the pituitary Primary: abnormality in the gland

  4. Pituitary Hormones Growth ACTH FSH TSH hormone and LH stimulates adrenal stimulates stimulate cortex thyroid gonads

  5. Question Which hormone(s) is/are secreted by the ovaries and testes? • GH • FSH and LH • TSH • ACTH and GH

  6. Answer • FSH and LH Rationale:Gonads are sex organs (ovaries and testes). These organs secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH).

  7. The Hypothalamus Controls Growth Hormone Release Hypothalamus • GH secretion stimulated by: • Hypoglycemia, fasting, starvation • Stress • GH inhibited by: • Increased glucose levels, free fatty acid release, and obesity • Cortisol GHRH Somatostatin stimulates inhibits Anterior pituitary Growth hormone

  8. Functions of Growth Hormone

  9. Growth Hormone Deficiency • Idiopathic GH deficiency • Lacks hypothalamic GHRH • Pituitary tumors, agenesis of the pituitary • Cannot produce GH • Laron-type dwarfism • Hereditary defect in IGF production

  10. Growth Hormone Excess • In childhood: gigantism • In adulthood: acromegaly

  11. Question Tell whether the following statement is true or false. GH deficiency may result in dwarfism.

  12. Answer True Rationale:Laron-type dwarfism is caused by a genetic inability to produce normal amounts of GH.

  13. The Hypothalamus Controls Gonadal Hormone Release hypothalamus • Excessive GnRH secretion can be stimulated by: • Hypothalamic tumors • Pituitary tumors • Giving high levels of GnRH causes the pituitary to become less responsive and reduces the effects of abnormal GnRH secretion GnRH stimulates anterior pituitary FSH LH production of gametes and gonadal hormones

  14. Thyroid Control • Thyroid releases T3 and T4 • Both are carried by binding proteins • T3 stimulates metabolism • T4 is inactive until converted into T3 in the tissues • Both exert negative feedback on the hypothalamus

  15. Thyroid Insufficiency Due to Lack of I • T3 and T4 are not made • There is no negative feedback to the hypothalamus • TRH and TSH continue to be made • If it is able, the thyroid will grow in response to the TSH

  16. Thyroid Imbalances • Hypothyroidism • Congenital • Acquired • Hashimoto thyroiditis • Thyroidectomy • Hyperthyroidism (thyrotoxicosis) • Graves disease • Thyroid tumors

  17. Question Tell whether the following statement is true or false. Simple goiter is caused by increased production of thyroid hormone.

  18. Answer False Rationale:Simple goiter is the result of iodine (I) insufficiency. Since I is necessary in order to produce thyroid hormone, a deficiency results in low serum levels of T3 /T4. This causes TSH to stimulate the thyroid gland to make more hormone (which it cannot do because it needs I). The cells of the thyroid gland hypertrophy in an effort to function (make thyroid hormone).

  19. Major Adrenal Cortical Hormones Hypothalamus Corticotropin-releasing hormone (CRH) Negative Anterior pituitary feedback Adrenal corticotrophic Negative hormone (ACTH) feedback Adrenal cortex Cortisol Testosterone Aldosterone

  20. Actions of Cortisol cortisol catabolism increased plasma immune/ proteins inflammatory increased systems suppressed muscle SNS response breakdown increased free fatty acids blood glucose increased increased

  21. Adrenal Cortical Disorders • Adrenal cortical insufficiency: inability to make all three hormones • Primary adrenal cortical insufficiency (Addison disease) • Secondary adrenal cortical insufficiency • Acute adrenal crisis • Excessive adrenal secretion • Glucocorticoid hormone excess (Cushing syndrome) • Hyperaldosteronism • Congenital adrenal hyperplasia • Decreased cortisol synthesis; other hormones may be increased or decreased

  22. Scenario Three men have adrenal problems. • One has hypoaldosteronism, one has an inability to make cortisol, and one has an inability to make testosterone. Question: • Which of them is most likely to develop: • Hypotension? • High CRH levels? • Hypoglycemia? • Hypervirilization? • Decreased libido? • Hyperkalemia?

  23. Scenario Two women have benign pituitary tumors. • One woman has lost weight and complains of being hot all the time; she presents as thin and nervous, with tachycardia and exophthalmos • The second woman has gained weight in her abdomen and presents with a round face and thin arms and legs with stretch marks; she says that at her last checkup her doctor told her she was prediabetic Question: • What hormones are being secreted by the pituitary tumors in these patients? Why?

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