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NEUROENDOCRINE SYSTEM

NEUROENDOCRINE SYSTEM. Anna L. Kiss Department Anatomy , Histology and Embryology Semmelweis University Budapest 2018. AUTOCRINE. ENDOCRINE (hormones). PARACRINE. NEUROENDOCRINE (neurohormone). MECHANISM OF SIGNAL TRANSMISSION. neuron.

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NEUROENDOCRINE SYSTEM

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  1. NEUROENDOCRINE SYSTEM Anna L. Kiss DepartmentAnatomy, Histology and Embryology Semmelweis University Budapest 2018

  2. AUTOCRINE ENDOCRINE (hormones) PARACRINE NEUROENDOCRINE (neurohormone) MECHANISM OF SIGNAL TRANSMISSION neuron ACCORDING TO THE PLACE OF EFFECT OF SECRETION

  3. Hypothalamo-hypophyseal system CEREBRAL HEMISPHERE CEREBELLAR HEMISPHERE LOWER BRAIN STEM UPPER BRAIN STEM = DIENCEPHALON

  4. Nuclei of thehypothalamus • Anteriorhypothalamus • anteriornucleus • praeopticarea • suprachiasmatic • paraventricularnucleus • supraopticnucleus • 2. Middlehypothalamus: • (nexttothethirdventricle) • dorsomedial • ventromedial • arcuate • infundibular (dopamine): most of them: hypothalamo-hypophysealtract • 3. Posteriorhypothalmus: • mamillary body • posteriornucleus

  5. Nuclei of thehypothalamus

  6. Nuclei of thehypothalamus

  7. Nuclei of thehypothalamus Parvocellularnuclei: Magnocellularnuclei:

  8. NEUROHYPOPHYSIS median eminence median eminence MEDIAN EMINENCE INFUNDIBULAR STEM INFUNDIBULAR PROCESS pars tuberalis infundibular stem infundibular process pars intermedia pars distalis

  9. SUPRAOPTICO-PARAVENTRICULO-HYPOPHYSEAL MAGNOCELLULAR SYSTEM III. ventricle • 2 magnocellularhypothalamicnuclei: • supraoptic • paraventricular (posterior pituitary)

  10. FUNCTION OF POSTERIOR PITUITARY HORMONES OXYTOCIN Contraction of uterinal smooth muscle (delivery) Contractionof the mammary smooth muscle (milk ejection) VASOPRESSIN (antidiuretic hormone, ADH) Vasoconstrictor, enhances the blood pressure Water absorption in the collective tubules of kidney

  11. Magnocellularnuclei of thehypothalamus

  12. Histology of thepostriorpituitary

  13. Histology of thepostriorpituitary pituicytes

  14. Development of thepituitarygland

  15. Hypothalamo-hypophysealsystem

  16. Histologicalstructure of theanteriorpituitary

  17. Histologicalstructure of theanteriorpituitary basophyls:10% acidophyls: 40% chomophobes: 50% chromophyls

  18. Histologicalstructure of theanteriorpituitary • Folliculo-stellatecells: • interconnectedbygapjunctions, containing connexon43 • throughthesegapjunctionstheytransmitsignalsfromtuberal part todistalone Interleukins, growth factors

  19. HORMONES OF THE ANTERIOR LOBE Trop hormones: stimulatory the target organ is another endocrine gland TSH (thyroid stimulating hormone) ACTH (adrenocorticotrop hormone) FSH (follicle stimulating hormone) LH (luteinizing hormone) STH (somatotrop hormone) = GH (growth hormone) LTH (luteotrop hormone, prolactin) Gonadotropichormones

  20. Histologicalstructure of theanteriorpituitary • Chromophylcells: trop (stimulating) hormones • STH (GH): regulatinghormones: GHRH, somatostatin, ghrelin • prolactin (LTH); dopamine has inhibitoryeffect, VIP and TRH stimulateitssecretion • TSH • ACTC • gonadotrpichormones: • FSH • LH

  21. STH: growth hormon: - acts on all cells of the body - stimulates the liver to produce and secrete insulun-like growth factor - results in body growth In the abcense of GH during development

  22. Growth hormon, STH, somatotrop hormon overproduction in adult GIGANTISM ACROMEGALY normal giant normal In adult

  23. Regulation of theanteriorpituitary

  24. Bloodsupply • internalcarotidartery: superiorhypophysealartery fenestratedcapillarynetwork hypophysealportalsystemrunningalongthe p. tuberalis secondfenestratedsinusoidalcapillarynetwork 2. circle of Willisii: inferior hypophyseal artery shortportalveins: towardthehypothalamus: feed back tothehypothalamusfromtheanteriorpituitary

  25. Regulation of theanteriorpituitary RELEASING HORMONES GnRH (gonadotropin-releasing hormones) TRH (thyreotrop hormone-releasing hormone) CRH (corticotrop hormone-releasing hormone) GRH (growth hormone-releasing hormone) INHIBITING HORMONES Somatostatin (growth hormone-inhibiting hormone) Dopamine (prolactin-inhibiting hormone)

  26. FEED-BACK MECHANISM ultrashort feedback (neural) hypophyseotroph neurons ultrashort feedback (humoral) anterior lobe short feedback troph hormones long feedback Béla Halász,in: Handbook of Clinical Endocrinology and Metabolic Diseases

  27. Histologicalstructure of theintermediatelobe of thepituitary

  28. Histologicalstructure of theintermeiatelobe of thepituitary Follicles: residual lumen of Rathke’spouch Parenchymalcells: derivedeitherfromthefolliculo-stellatecellsorvarious hormon secretingcells Basophyls: α and βendorphin (morphin-relatedcompound; MSH in frog in human MSH is notdistinct, just a fewamount byproduct of β-lipotrophic hormon cellsaretakenascorticotropes

  29. Tuberal part of thepituitary

  30. Tuberal part of thepituitary • highlyvascularized: veins of thehypothalamo-hypophysealsystem • parenchymalcells: in clusters, cords in association of bloodvessels • smallfollicleslinedbycuboidalcells • immunoreactivityfor ACTH, FSH and LH

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