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INTRODUCTION TO THE ENDOCRINE SYSTEM AND THE PITUITARY-HYPOTHALAMIC AXIS

INTRODUCTION TO THE ENDOCRINE SYSTEM AND THE PITUITARY-HYPOTHALAMIC AXIS. D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY. NERVOUS SYSTEM “WIRED” CHEMICAL SIGNAL AT TARGET CELL RAPID BRIEF DURATION. ENDOCRINE SYSTEM “WIRELESS” CHEMICAL SIGNAL AT TARGET CELL SLOW LONG DURATION.

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INTRODUCTION TO THE ENDOCRINE SYSTEM AND THE PITUITARY-HYPOTHALAMIC AXIS

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  1. INTRODUCTION TO THE ENDOCRINE SYSTEM AND THE PITUITARY-HYPOTHALAMIC AXIS D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY

  2. NERVOUS SYSTEM “WIRED” CHEMICAL SIGNAL AT TARGET CELL RAPID BRIEF DURATION ENDOCRINE SYSTEM “WIRELESS” CHEMICAL SIGNAL AT TARGET CELL SLOW LONG DURATION COMPARISON OF ENDOCRINE AND NERVOUS SYSTEMS

  3. CATEGORIES OF HORMONES • PEPTIDES • AMINES • STEROIDS

  4. PEPTIDES • HYDROPHILIC • DISSOLVED IN PLASMA • RECEPTOR ON CELL SURFACE • SECOND MESSENGERS • MAY ACTIVATE SPECIFIC GENES TO REGULATE PROTEIN SYNTHESIS

  5. PEPTIDE HORMONES • HYPOTHALAMIC • PITUITARY • PANREATIC • PARATHYROID • GI • KIDNEY • LIVER • HEART

  6. AMINES • THYROID HORMONE • CATECHOLAMINES • ALL DERIVED FROM AMINO ACID TYROSINE • UNIQUE SYNTHETIC AND SECRETORY PATHWAYS

  7. STEROIDS • DERIVED FROM CHOLESTEROL • LIPOPHILIC • RECEPTOR IN CYTOPLASM • MAY ACTIVATE SPECIFIC GENES TO INITIATE PROTEIN SYNTHESIS • ADRENAL CORTICAL • GONADAL • PLACENTAL

  8. PLASMA CONCENTRATION OF HORMONES • DEPENDS ON RATE OF SECRETION • NEGATIVE FEEDBACK • NEUROENDOCRINE REFLEXES • DIURNAL RHYTHMS

  9. TYPES OF ENDOCRINE DISORDERS • HORMONE EXCESS • HORMONE DEFICIENCY • DECREASED RESPOSIVENESS OF RECEPTORS

  10. THE PITUITARY- HYPOTHALAMIC AXIS INTERFACING THE NERVOUS SYSTEM WITH THE ENDOCRINE SYSTEM

  11. HYPOTHALAMUS AND POSTERIOR PITUITARY NEUROSECRETORY NEURONS HYPOTHALAMUS VASOPRESSIN POSTERIOR PITUITARY OXYTOCIN SYSTEMIC ARTERY ANTERIOR PITUITARY SYSTEMIC VEIN

  12. HYPOTHALAMUS AND ANTERIOR PITUITARY NEUROSECRETORY NEURONS HYPOTHALAMUS • ANTERIOR • PITUITARY: • TSH • ACTH • PROLACTIN • GROWTH • HORMONE • LH • FSH POSTERIOR PITUITARY

  13. CLASSIFICATION OF ANTERIOR PITUITARY HORMONES • GLYCOPROTEIN FAMILY: TSH, FSH,LH • GROWTH HORMONE PROLACTIN FAMILY: GH OR STH • PROOPIOMELANOCORIN FAMILY: ACTH, -LIPOTROPIN, -ENDORPHIN

  14. HYPOTHALAMIC-HYPOPHYSEAL PORTAL SYSTEM • SECRETED BY NERVE CELLS IN HYPOTHALAMUS • VESSELS PASS THROUGH STALK OF PITUITARY FROM HYPOTHALAMUS TO ANTERIOR PITUITARY • CARRY HYPOTHALAMIC REGULATORY HORMONES

  15. HYPOTHALAMIC REGULATORY HORMONES • HYPOPHYSIOTROPIC HORMONES • CONTROL THE SECRETION OF OTHER HORMONES BY ACTING ON ENDOCRINE TISSUE

  16. HYPOTHALAMIC RELEASING AND INHIBITING HORMONES (HYPOPHYSIOTROPIC) • CONTROL THE SECRETION OF ANTERIOR PITUITARY TROPIC HORMONES • TRH:THYROTROPIN-RELEASING HORMONE • PRF:PROLACTIN RELEASING FACTOR • PIF:PROLACTIN INHIBITING FACTOR • GHRH:GROWTH HORMONE RELEASING HORMONE • SRIF: SOMATOTROPIN RELEASE-INHIBITING FACTOR • CRH:CORTICOTROPHIN RELEASING HORMONE • GnRH: GONADOTROPIN RELEASING HORMONE

  17. HIERARCHICAL CONTROL INPUT HYPOTHALAMUS HORMONE 1 (RELEASING/INHIBITING) H/H PORTAL SYSTEM ANTERIOR PITUITARY HORMONE 2 (TROPIC) SYSTEMIC CIRCULATION ENDOCRINE GLAND HORMONE 3 SYSTEMIC CIRCULATION TARGET CELLS

  18. NEGATIVE FEEDBACK INPUT HYPOTHALAMUS HORMONE 1 (RELEASING/INHIBITING) H/H PORTAL SYSTEM ANTERIOR PITUITARY HORMONE 2 (TROPIC) SYSTEMIC CIRCULATION ENDOCRINE GLAND HORMONE 3 SYSTEMIC CIRCULATION TARGET CELLS

  19. ANTERIOR PITUITARY HORMONES:TSH • THYROID GLAND • THYROID HORMONES (T3 & T4 )

  20. ANTERIOR PITUITARY HORMONES:ACTH • ADRENAL CORTEX • CORTISOL

  21. ANTERIOR PITUITARY HORMONES:PROLACTIN • MAMMARY GLANDS • BREAST GROWTH AND MILK SECRETION

  22. LIVER SOMATOMEDINS BONE SOFT TISSUE GROWTH MANY TISSUES INTERMEDIARY METABOLISM INCREASE OR DECREASE ANTERIOR PITUITARY HORMONES: GROWTH HORMONE

  23. LH:LUTEINIZING HORMONE SEX HORMONE SECRETION F: ESTROGEN AND PROGESTERONE M: TESTOSTERONE FSH:FOLLICLE STIMULATING HORMONE GAMETE PRODUCTION OVA SPERM ANTERIOR PITUITARY HORMONES:LH & FSH: ACT ON GONADS

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