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” CHEMICAL SIGNAL AT TARGET CELL SLOW LONG DURATION SPECIFIC RECEPTORS

WHAT IS A SIGNAL? SEMIOTICS INFORMATION THEORY NERVOUS SYTEM ENDOCRINE PARACRINE ENDOCRINE ANTIBODIES AND OTHER FOREIGN SUBSTANCES PARALLEL PROCESSING

CHEMICAL SIGNALS SIGNALING MOLECULE IS SECRETED TRAVELS FRON ONE SITE TO ANOTHER RECEPTOR AT TARGET BINDING TO RECEPTOR EFFECTS SOME CHANGE

ELEMENTS OF CELL SIGNALLING MECHANISMS SIGNAL MOLECULES RECEPTORS SIGNAL TRANSDUCTION

SIGNAL MOLECULES (FIRST MESSENGERS) NEUROTRANSMITTERS HORMONES LOCAL MEDIATORS

EXAMPLES OF SIGNALLING MOLECULES (SEE TABLE 1 IN TEXT)

RECEPTORS CELL MEMBRANE: HYDROPHILIC SIGNAL MOLECULES (POLYPEPTIDES, CATECHOLAMINES) CYTOPLASMIC: HYDROPHOBIC SIGNAL MOLECULES (STEROIDS, VITAMIN D, THYROID HORMONE*) *BOUND TO CARRIER PROTEIN

LIGANDS, AGONISTS AND ANTAGONISTS LIGANDS BIND TO RECEPTORS IN A SPECIFIC MANNER LIGANDS THAT ELICIT A PHYSIOLOGICAL RESPONSE ARE AGONISTS LIGANDS THAT OCCUPY THE RECEPTOR BUT ELICIT NO RESPONSE ARE ANTAGONISTS (OR “BLOCKERS”)

EXAMPLES OF ANTAGONISTS PROPRANOLOL BLOCKS THE EFFECTS OF CATECHOLAMINES BY BINDING TO THEIR RECEPTORS SPIRONOLACTONE BLOCKS ALDOSTERONE (DIURETIC)

REGULATION OF RECEPTOR QUANTITY AS A CONTROL MECHANISM DESENSITIZATION BY DOWNREGULATION DUE TO INCREASED ANTAGONIST LEVELS INTERNALIZATION OF COMPLEX BY ENDOCYTOSIS RECEPTOR SYNTHESIS (UPREGULATION)

AN EXAMPLE OF RECEPTOR RECYCLING

MEMBRANE RECEPTORS G-PROTEIN RECEPTOR SUPERFAMILY MORE THAN 250 MEMBERS SERPENTINE GLYCOPROTEINS LOOP BACK AND FORTH THROUGH MEMBRANE EXTRACELLULAR DOMAIN: AMINO TERMINAL PEPTIDE AND THREE LOOPS (HYDROPHILIC REGIONS) IN THE MEMBRANE:SEVEN ALPHA HELICES OF ABOUT 25 HYDROPHOBIC AA SEE FIG 8 IN TEXT

CATEGORIES OF HORMONES PEPTIDES AMINES STEROIDS

PEPTIDES HYDROPHILIC DISSOLVED IN PLASMA RECEPTOR ON CELL SURFACE cAMP OR CALCIUM AS SECOND MESSENGERS ACTIVATE SPECIFIC GENES TO INITIATE PROTEIN SYNTHESIS

PEPTIDE HORMONES HYPOTHALAMIC PITUITARY PANREATIC PARATHYROID GI KIDNEY LIVER HEART

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

STEROIDS LIPOPHILIC RECEPTOR IN CYTOPLASM ACTIVATE SPECIFIC GENES TO INITIATE PROTEIN SYNTHESIS ADRENAL CORTICAL GONADAL PLACENTAL

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

TYPES OF ENDOCRINE DISORDERS HORMONE EXCESS HORMONE DEFICIENCY DECREASED RESPOSIVENESS OF RECEPTORS

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

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