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The Pituitary Hormones

The Pituitary Hormones. Chapter 13. (c) 2003 Brooks/Cole - Thomson Learning. Hypothalamic-Pituitary Systems. The pituitary is controlled largely by the hypothalamus : interaction of the nervous and endocrine system. Three separate glands Anterior lobe: endocrine, 6 hormones

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The Pituitary Hormones

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  1. The Pituitary Hormones Chapter 13

  2. (c) 2003 Brooks/Cole - Thomson Learning Hypothalamic-Pituitary Systems The pituitary is controlled largely by the hypothalamus: interaction of the nervous and endocrine system. Three separate glands Anterior lobe: endocrine, 6 hormones Intermediate : minor, 1 Posterior : neuroendocrine, 2 Hypothalamus Pituitary stalk Optic chiasm Posterior lobe Anterior lobe Intermediate lobe Pituitary gland Fig 13-1b, pg 410

  3. (c) 2003 Brooks/Cole - Thomson Learning Paraventricular nucleus Supraoptic nucleus Hypothalamus Posterior pituitary contains the axons from the neurons that have their cell bodies in the hypothalamus. Posterior pituitary To venous circulation Fig 13-3, pg 412 Arterial blood supply

  4. Gonadotropic Thyroid- Proactin hormones stimulating ACTH Growth (FSH and LH) hormone hormone (c) 2003 Brooks/Cole - Thomson Learning Cell bodies of neurons that produce releasing/inhibiting hormones Hypothalamus Hypothalamus releases hormones at median eminence and those hormones are carried to anterior via portal vein. Primary capillaries in median eminence Arterial flow Long Portal veins Releasing hormones Anterior pituitary hormone ANTERIOR PITUITARY Secretory cells that produce anterior pituitary hormones Anterior pituitary hormones Venous outflow Fig 13-4, pg 413

  5. Paraventricular nucleus Supraoptic nucleus Oxytocin and ADH are synthesized in soma in hypothalamus and released from nerve terminals in post. Pituitary. Various inputs influence supraoptic and paraventricular neurons to control secretion. Cell bodies of neurons that produce posterior pituitary hormones Posterior pituitary capillaries Venous outflow Arterial inflow

  6. Hypothalamic releasing hormones travel to ant. pit. and control secretion from cells there. One hypothalamic hormone may control more than one ant. pit. hormone (stim. or inhibit).

  7. Posterior Pituitary Hormones Antidiuretic hormone (ADH) Effect: waterretention by kidneys Stimulator: 1) an increase in osmolality in blood and ECF 2) a large decrease in blood volume

  8. Posterior Pituitary Hormones Suckling and other stimuli trigger oxytocin release to transfer milk from alveoli to ducts.

  9. Anterior Pituitary Hormones Somatotropes (50%) = GH corticotropes (20%) = ACTH thyrotropes (5%) = TSH Gonadotropes (5%) = LH and FSH Lactotropes (variable) = Prolactin

  10. Anterior Pituitary Hormones LH and FSH (the gonadotropins) :promote production of sperm, egg, and sex steroids. Prolactin Stimulation of alveolar cells to make milk. Release is controlled by PRF and PIH (DA) ACTH is controlled by CRH; Promotion of the synthesis and secretion of cortisol from adrenal cortex

  11. (c) 2003 Brooks/Cole - Thomson Learning Growth Hormone GH is released in pulses, with a major peak during deep sleep before REM. Sleep Plasma GH concentration (relative units) Noon 6 AM 6 PM Midnight Time of day Fig 13-5, pg 418

  12. (c) 2003 Brooks/Cole - Thomson Learning Growth Hormone Stimulator Deep sleep, low blood glucose stimulation Stress physical trauma infection psychological stress Amino acid (especially, arginine) Inhibitor REM sleep High blood glucose stimulation Chemical stimuli Stress centers In the brain Sleep center In the brain Hypothalamus Portal vein GHRH (+) Somatostatin (-) Somatotrophs of Anterior pituitary GHRH and somatostatin in hypothalamus; final pathway forcontrolling GH Growth hormone Liver Somatomedins Fig 13-6, pg 419

  13. Growth Hormone • GH effects: tissue growth (including bone growth) • Anabolic hormone Insulin-like GH effects: liver and muscle protein synthesis; anti-insulin: inhibits glucose uptake

  14. (c) 2003 Brooks/Cole - Thomson Learning Growth Hormone GROWTH HOMONE LIVER ADIPOSE MUSCLE Glucose uptake Amino acid uptake Protein synthesis Protein synthesis RNA synthesis Lipolysis Glucose uptake Glucoenogenesis Insulin-like effects of GH Somatomedin production Decreased adiposity Increased muscle mass Anti-insulin effects of GH Fig 13-7a, pg 420

  15. IGF-II IGF-I Growth Hormone IGF-I stimulates bone growth by stimulating chondrocytes, which make cartilage. SOMATOMEDINS MANY ORGANS AND TISSUES CHONDROCYTES OF BONE Protein synthesis RNA synthesis DNA synthesis Cell size and number Collagen synthesis Protein synthesis Cell proliferation Increased linear growth Increased tissue growth Increased organ size Fig 13-7b, pg 420

  16. IGF-II IGF-I Growth Hormone IGF-II stimulates tissue growth and repair by stimulating RNA and protein synthesis. SOMATOMEDINS MANY ORGANS AND TISSUES CHONDROCYTES OF BONE Protein synthesis RNA synthesis DNA synthesis Cell size and number Collagen synthesis Protein synthesis Cell proliferation Increased linear growth Increased tissue growth Increased organ size

  17. Growth Hormone Deficiency Childhood deficiencyresults in dwarfism Adulthood: not evident symptom

  18. Growth Hormone Overproduction Gigantism is childhood GH excess; acromegaly from adulthood GH excess.

  19. Thyroid-Stimulating Hormone TSH: stimulates thyroid cell growth and secretion of thyroid hormone

  20. (c) 2003 Brooks/Cole - Thomson Learning Thyroid-Stimulating Hormone The thyroid glandhas two large lobes below the larynx, rich blood supply, and large growth capacity Weight: 10-20 g Larynx Thyroid gland Thyroid isthmus Trachea Fig 13-10, pg 422

  21. Thyroid-Stimulating Hormone The thyroid gland consists of cells that are arranged in follicles. In a healthy adult, there are 3 million follicles.

  22. Thyroid-Stimulating Hormone Each thyroid follicle is filled with colloid and major component of colloid is thyroglobulin.

  23. (c) 2003 Brooks/Cole - Thomson Learning Tyrosine Thyroxine (T4) and triiodothyronine (T3) are its main products; MIT and DIT are minor. Diiodotyrosine (DIT) Monoiodotyrosine (MIT) T4 (thyroxine) Fig 13-13, pg 424 T3

  24. (c) 2003 Brooks/Cole - Thomson Learning Thyrogloblulin Thyroglob-ulin, the T4 and T3 precursor, is a glyco-protein secreted into the colloid. Apical surface Thyroglobulin synthesis Basal surface Interstitial fluid Amino acids Fig 13-14, pg 425

  25. (c) 2003 Brooks/Cole - Thomson Learning Thyrogloblulin Coupling Iodination Thyroglobulin tyrosine is iodinated to MIT/DIT and coupled to make bound T3 and T4. Iodide oxidation Iodine trap Interstitial fluid Fig 13-14, pg 425

  26. (c) 2003 Brooks/Cole - Thomson Learning Follicle cells endocytose some colloid, fuses it with lysosomes, and releases T3 and T4. Pinocytosis Lysosome Phagolysosome Deiodeinase T3 T4 Plasma Fig 13-14, pg 425

  27. (c) 2003 Brooks/Cole - Thomson Learning Environmental influences Hypothalamic-pituitary-thyroid axis Low temperature hypothalamusTRH  pituitaryTSH  thyroidT4/T3 body. Other brain centers Temperature- regulatory Centers (hypothalamus) Hypothalamus TRH Anterior pituitary TSH I- Thyroid gland T3 and T4 Biological effects Heat production Metabolism of carbohydrates, proteins, and fats

  28. Iodide deficiency  low T4/T3low feedback inhibition high TSH  goiter.

  29. T3 is more potent than T4, and target cells convert T4 to T3.

  30. Effects of thyroid hormone • Thyroid hormones • Stimulate calorigenesis • Increase circulatory sensitivity to sympathetic nervous system. • Increase oxygenation of blood • Increase • glucose uptake, glycogen formation, lipolysis, • biphasic protein synthesis

  31. Effects of thyroid hormone • Thyroid hormones • Promote bone growth • Promote development of nervous system • Neural branching • Myelinization of nerve

  32. Excess secretion; Hyperthyroidism Symptom high metabolism, High heart rate; weight loss; heat intolerance.

  33. Excess secretion; Hyperthyroidism

  34. Excess secretion; Hyperthyroidism

  35. Hypothyroidism Deficiency of thyroid hormone

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