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THE ENDOCRINE SYSTEM

THE ENDOCRINE SYSTEM. D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM. COMPARISON OF ENDOCRINE AND NERVOUS SYSTEMS. NERVOUS SYSTEM “WIRED” CHEMICAL SIGNAL AT TARGET CELL RAPID BRIEF DURATION CLOSE ANATOMICAL PROXIMITY. ENDOCRINE SYSTEM “WIRELESS”

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THE ENDOCRINE SYSTEM

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  1. THE ENDOCRINE SYSTEM D. C. MIKULECKY PROFESSOR OF PHYSIOLOGY AND FACULTY MENTORING PROGRAM

  2. COMPARISON OF ENDOCRINE AND NERVOUS SYSTEMS • NERVOUS SYSTEM • “WIRED” • CHEMICAL SIGNAL AT TARGET CELL • RAPID • BRIEF DURATION • CLOSE ANATOMICAL PROXIMITY • ENDOCRINE SYSTEM • “WIRELESS” • CHEMICAL SIGNAL AT TARGET CELL • SLOW • LONG DURATION • SPECIFIC RECEPTORS

  3. CATEGORIES OF HORMONES • PEPTIDES • AMINES • STEROIDS

  4. PEPTIDES • HYDROPHILIC • DISSOLVED IN PLASMA • RECEPTOR ON CELL SURFACE • cAMP OR CALCIUM AS SECOND MESSENGERS • ACTIVATE SPECIFIC GENES TO INITIATE 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 • LIPOPHILIC • RECEPTOR IN CYTOPLASM • 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. HYPOTHALAMUS AND POSTERIOR PITUITARY NEUROSECRETORY NEURONS HYPOTHALAMUS VASOPRESSIN POSTERIOR PITUITARY OXYTOCIN SYSTEMIC ARTERY ANTERIOR PITUITARY SYSTEMIC VEIN

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

  12. HYPOTHALAMIC-HYPOPHYSEAL PORTAL SYSTEM • VESSELS PASS THROUGH STALK OF PITUITARY FROM HYPOTHALAMUS TO ANTERIOR PITUITARY • CARRY HYPOTHALAMIC REGULATORY HORMONES

  13. HYPOTHALAMIC REGULATORY HORMONES • TROPIC HORMONES • CONTROL THE SECRETION OF OTHER HORMONES BY ACTING ON ENDOCRINE TISSUE

  14. HYPOTHALAMIC RELEASING AND INHIBITING HORMONES • CONTROL THE SECRETION OF ANTERIOR PITUITARY TROPIC HORMONES • TRH:THYROTROPIN-RELEASING HORMONE • PRH:PROLACTIN RELEASING HORMONE • PIH:PROLACTIN INHIBITING HORMONE • GHRH:GROWTH HORMONE RELEASING HORMONE • GHIH: GROWTH HORMONE INHIBITING HORMONE • CRH:CORTICOTROPHIN RELEASING HORMONE

  15. 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

  16. 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

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

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

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

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

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

  22. CONTROL OF GROWTH • GENETIC • DIET • DISEASE • HORMONES

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

  24. METABOLIC ACTIONS OF GROWTH HORMONE • MOBILIZES TRIGLYCERIDE FAT STORED IN ADIPOSE TISSUE • CONSERVES GLUCOSE FOR BRAIN

  25. GROWTH PROMOTING ACTIONS OF GROWTH HORMONE • SOFT TISSUES: STIMULATES CELL DIVISION, INCREASES SIZE OF CELLS • STIMULATES ALMOST ALL ASPECTS OF PROTEIN SYNTHESIS • INHIBITS PROTEIN DEGRADATION • PROMOTES UPTAKE OF AMINO ACIDS

  26. GROWTH PROMOTING ACTIONS OF GROWTH HORMONE • BONE: PROMOTES GROWTH OF LONG BONES • THICKNESS • LENGTH • AT END OF ADOLESCENCE, SEX HORMONES STOP THIS ACTION

  27. GROWTH HORMONE ACTS THROUGH SOMATOMEDINS • PEPTIDE MEDIATORS • PRODUCED IN LIVER AND OTHER TISSUES • ALSO PARACRINE EFFECTS

  28. GHRH AND GHIH • ANTAGONIST IN CONTROL OF GROWTH HORMONE SECRETION • NEGATIVE FEEDBACK • DIURNAL RHYTHM: GH SECRETED AT NIGHT • EXERCISE, STRESS, HYPOGLYCEMIA

  29. ABNORMAL GH SECRETION • DEFICIENCY: DWARFISM, REDUCED MUSCLE STRENGTH, DECREASED BONE DENSITY • EXCESS:GIGANTISM, ACROMEGLY

  30. THE THYROID GLAND • OVER TRACHEA • THYROGLOBULIN • TETRAIODOTHYRONINE • TRIIODOTHYRONINE • IODINE REQUIRED FROM DIETARY INTAKE

  31. THYROID HORMONE’S EFFECTS • METABOLIC RATE: INCREASED BMR • CALOROGENIC: INCREASED HEAT PRODUCTION • SYMPATHOMIMETIC: FLIGHT OR FIGHT • CARDIOVASCULAR:INCREASES RESPONSIVENESS OF HEART • GROWTH: ESSENTIAL FOR NORMAL GROWTH • NERVOUS SYSTEM:DEVELOPMENT AND ADULT ACTIVITY

  32. REGULATION OF THYROID SECRETION COLD IN CHILDREN HYPOTHALAMUS STRESS - + TRH ANTERIOR PITUITARY TSH THYROID GLAND THYROID HORMONE TARGET ORGANS

  33. ABNORMALITIES OF THYROID FUNCTION • HYPO • REDUCED BMR • POOR TOLERANCE OF COLD • GAIN OF WEIGHT • FATIGUE • SLOW, WEAK PULSE • SLOW REFLEXES AND MENTATION • MYXEDEMA • GOITER • CRETINISM • HYPER • GRAVE’S DISEASE:TSI • EXOPHTALMOS • GOITER

  34. THE ADRENAL GLANDS • CORTEX: STEROID HORMONES SECRETED • MEDULLA: CATECHOLAMINES

  35. CORTEX: STEROID HORMONES SECRETED • MINERALOCORTICOIDS • GLUCOCORTICOIDS • SEX HOMONES

  36. MINERALOCORTICOIDS • ALDOSTERONE • ELECTROLYTE BALANCE • BLOOD PRESSURE • RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM

  37. GLUCOCORTICOIDS • CORTISOL • GLOCONEOGENESIS • PERMISSIVE ACTIONS • STRESS ADAPTATION • ANTI-INFLAMITORY AND IMMUNOSUPPRESSANT

  38. REGULATION OF CORTISOL SECRETION DIURNAL RHYTHM HYPOTHALAMUS STRESS + - + CRH ANTERIOR PITUITARY INCREASED BLOOD GLUCOSE BLOOD AA BLOOD FATTY ACIDS - ACTH ADRENAL CORTEX CORTISOL TARGET ORGANS

  39. SEX HOMONES • ANDROGENS (TESTOSTERONE) • ESTROGENS • LESS THAN GONADS

  40. ADRENAL OVERSECRETION • MINERALCORTICOIDS: SODIUM RETENTION, POTASSIUM DEPLETION • CORTISOL:EXCESS GLUCONEOGENESIS-EXCESS GLUCOSE DEPOSITED AS FAT • ANDROGEN:MASCULINIZATION, PSEUDOHERMAPHODITISM, PRECOCIOUS PSEUDOPUBERTY, NO EFFECT IN ADULT MALES

  41. ADRENAL INSUFFICIENY • CORTEX: ADDISON’S DISEASE • POOR RESPONSE TO STRESS • LACK OF PERMISSIVE ACTION • POTASSIUM RETENTION • HYPOTENSION

  42. MEDULLA: CATECHOLAMINES • A MODIFIED SYMPATHETIC POST GANGLIONIC NEURON • EPINEPHRINE

  43. ACTIONS OF EPINEPHRINE • MIMICS SYMPATHETIC NS • MOBILIZES STORED FAT AND CARBOHYDRATE • HEART AND BLOOD VESSELS

  44. GENERAL ADAPTATION SYNDROME • FLIGHT OR FIGHT • EPINEPHRINE • CRH-ACTH-CORTISOL • RENIN-ANGIOTENSIN-ALDOSTERONE • VASOPRESSIN • COORDINATED BY HYPOTHALAMUS • CAN BE INDUCED PSYCHOSOCIALLY

  45. CONTROL OF FUEL METABOLISM • GLYCOGENESIS • GLYCOGENOLYSIS • GLUCONEOGENESIS • PROTEIN SYNTHESIS • PROTEIN DEGRADATION • FAT SYNTHESIS • FAT BREAKDOWN

  46. ANABOLISM VS CATABOLISM • BUILD UP VS BREAKDOWN OF LARGE MOLECULES • ANABOLISM REQUIRES ENERGY (ATP) • CATABOLISM:ENERGY PRODUCTION

  47. PANCREATIC HORMONES • INSULIN • GLUCAGON

  48. INSULIN: ACTION ON BLOOD SUGAR • BETA CELLS IN ISLETS OF LANGERHANS: INSULIN • FACILITIES GLUCOSE ENTRY INTO CELLS • STIMULATES GLYCOGENESIS • INHIBITS GLYCOGENOLYSIS • INHIBITS GLUCONEOGENESIS

  49. INSULIN: ACTION ON FAT • INCREASES TRANSPORT INTO ADIPOSE CELLS • PROMTES TRIGLYCERIDE SYNTHESIS • INHIBITS LIPOLYSIS

  50. INSULIN: ACTION ON PROTEIN • PROMOTES UPTAKE OF AA BY MUSCLE AND OTHER TISSUE • PROMOTES PROTEIN SYNTHESIS • INHIBITS PROTEIN DEGRADATION

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