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NROSCI/BIOSC 1070 MSNBIO/NROSCI 2070 September 8, 2014

NROSCI/BIOSC 1070 MSNBIO/NROSCI 2070 September 8, 2014. Control 2. Functions of Hormones. Hormones act on their target cells in one of three basic ways: Control the rate of enzymatic reactions Control transport of molecules across cell membranes Control gene expression and synthesis.

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NROSCI/BIOSC 1070 MSNBIO/NROSCI 2070 September 8, 2014

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  1. NROSCI/BIOSC 1070 MSNBIO/NROSCI 2070 September 8, 2014 Control 2

  2. Functions of Hormones • Hormones act on their target cells in one of three basic ways: • Control the rate of enzymatic reactions • Control transport of molecules across cell membranes • Control gene expression and synthesis

  3. Types of Hormones • Peptides • Amino Acids • Steroids

  4. Divisions of Pituitary • Anterior pituitary • (also called adenohypophysis) • True glandular tissue • Posterior pituitary • (also called neurohypophysis) • Extension of brain

  5. Hypothalamic-Hypophyseal Portal System

  6. Ultra Short Loop Feedback Short Loop Feedback Long Loop Feedback Tropic Hormones — Control the Release of Other Hormones Anterior Pituitary Hormones are Tropic Hormones End Products Regulate Tropic Hormone Secretion

  7. Anterior Pituitary Hormones No KnownTropic Role

  8. Proopiomelanocortin(POMC) POMC is cleaved within a vesicle to form ACTH, β-Endorphin, γLPH, and 16K fragment

  9. Hypophysiotropic Hormones: Control Anterior Pituitary Secretions Others likely exist, but have not been discovered because of their low concentrations in blood

  10. What happens if feedback mechanisms are dysfunctional? • Tumors can produce large amounts of hormones without feedback regulation • Autoimmune diseases can damage receptors on hormone-secreting cells, so they no longer respond to tropic hormones • Intracellular signal transduction pathways can become aberrantly altered, thereby affecting how hormone-producing cells respond to tropic hormones.

  11. Posterior Pituitary Hormones • Arginine Vasopressin • Named as such because the first vasopressin discovered was from pig; this hormone has a lysine instead of arginine as residue 8 • Produces vasoconstriction when present in high concentrations (hence the name) • Affects water reabsorption in kidney at lower concentrations, hence the secondary name: antidiuretic hormone • Oxytocin • Triggers uterine contractions during birthing • Triggers milk release from mammary glands during suckling • May have roles in cardiovascular control and renal function (men and women who are not of child-bearing age also synthesize oxytocin)

  12. Posterior Pituitary Hormones • Posterior pituitary hormones are synthesized by neurons in the paraventricular and supraoptic nuclei of the hypothalamus • These hormones are released like neurotransmitters when the neurons fire • The release of the hormones is dependent on the number of neurons that fire and the rate and duration of their firing

  13. Examples of Some Hormones

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