INTRODUCTION TO THE ENDOCRINE SYSTEM AND THE PITUITARY-HYPOTHALAMIC AXIS

D. C. MIKULECKYPROFESSOR OF PHYSIOLOGY

COMPARISON OF ENDOCRINE AND NERVOUS SYSTEMS

NERVOUS SYSTEM “WIRED”CHEMICAL SIGNAL

AT TARGET CELLRAPIDBRIEF DURATION

ENDOCRINE SYSTEM“WIRELESS”CHEMICAL SIGNAL

AT TARGET CELLSLOWLONG DURATION

CATEGORIES OF HORMONESPEPTIDES

AMINES

STEROIDS

PEPTIDESHYDROPHILICDISSOLVED IN PLASMARECEPTOR ON CELL SURFACESECOND MESSENGERSMAY ACTIVATE SPECIFIC GENES TO

REGULATE PROTEIN SYNTHESIS

PEPTIDE HORMONESHYPOTHALAMICPITUITARYPANREATICPARATHYROIDGIKIDNEYLIVERHEART

AMINESTHYROID HORMONECATECHOLAMINESALL DERIVED FROM AMINO ACID

TYROSINEUNIQUE SYNTHETIC AND SECRETORY

PATHWAYS

STEROIDSDERIVED FROM CHOLESTEROL LIPOPHILICRECEPTOR IN CYTOPLASMMAY ACTIVATE SPECIFIC GENES TO

INITIATE PROTEIN SYNTHESISADRENAL CORTICALGONADALPLACENTAL

PLASMA CONCENTRATION OF HORMONESDEPENDS ON RATE OF SECRETIONNEGATIVE FEEDBACKNEUROENDOCRINE REFLEXESDIURNAL RHYTHMS

TYPES OF ENDOCRINE DISORDERSHORMONE EXCESS

HORMONE DEFICIENCY

DECREASED RESPOSIVENESS OF RECEPTORS

THE PITUITARY- HYPOTHALAMIC AXIS

INTERFACING THE NERVOUS SYSTEM WITH THE ENDOCRINE SYSTEM

HYPOTHALAMUS AND POSTERIOR PITUITARY

HYPOTHALAMUSNEUROSECRETORYNEURONS

ANTERIOR PITUITARY

POSTERIORPITUITARY

SYSTEMICARTERY

SYSTEMICVEIN

VASOPRESSINOXYTOCIN

HYPOTHALAMUS AND ANTERIOR PITUITARY

HYPOTHALAMUSNEUROSECRETORYNEURONS

ANTERIOR PITUITARY:•TSH•ACTH•PROLACTIN•GROWTH HORMONE•LH•FSH

POSTERIORPITUITARY

CLASSIFICATION OF ANTERIOR PITUITARY HORMONES

GLYCOPROTEIN FAMILY: TSH, FSH,LHGROWTH HORMONE PROLACTIN

FAMILY: GH OR STHPROOPIOMELANOCORIN FAMILY:

ACTH, -LIPOTROPIN, -ENDORPHIN

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

HYPOTHALAMIC REGULATORY HORMONES

HYPOPHYSIOTROPIC HORMONESCONTROL THE SECRETION OF OTHER

HORMONES BY ACTING ON ENDOCRINE TISSUE

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

HIERARCHICAL CONTROL

INPUT

HORMONE 1 (RELEASING/INHIBITING)

HORMONE 2 (TROPIC)

HORMONE 3

TARGETCELLS

SYSTEMIC CIRCULATION

SYSTEMIC CIRCULATION

H/H PORTAL SYSTEM

HYPOTHALAMUS

ANTERIOR PITUITARY

ENDOCRINE GLAND

NEGATIVE FEEDBACK

INPUT

HORMONE 1 (RELEASING/INHIBITING)

HORMONE 2 (TROPIC)

HORMONE 3

TARGETCELLS

SYSTEMIC CIRCULATION

SYSTEMIC CIRCULATION

H/H PORTAL SYSTEM

HYPOTHALAMUS

ANTERIOR PITUITARY

ENDOCRINE GLAND

ANTERIOR PITUITARY HORMONES:TSH

THYROID GLAND

THYROID HORMONES (T3 & T4 )

ANTERIOR PITUITARY HORMONES:ACTH

ADRENAL CORTEX

CORTISOL

ANTERIOR PITUITARY HORMONES:PROLACTIN

MAMMARY GLANDS

BREAST GROWTH AND MILK SECRETION

ANTERIOR PITUITARY HORMONES: GROWTH HORMONE

LIVERSOMATOMEDINSBONESOFT TISSUEGROWTH

MANY TISSUESINTERMEDIARY

METABOLISMINCREASE OR

DECREASE

ANTERIOR PITUITARY HORMONES:LH & FSH: ACT ON GONADS

LH:LUTEINIZING HORMONE

SEX HORMONE SECRETION

F: ESTROGEN AND PROGESTERONE

M: TESTOSTERONE

FSH:FOLLICLE STIMULATING HORMONE

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