The Endocrine System


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  • effect that RHs and IHs released from the hypothalamus go immediately without dilution to their target.
  • The Endocrine System

    1. 1. Chapter 19 ENDOCRINE SYSTEM <ul><li>Compare the basic organization and function of the ES and the NS </li></ul><ul><li>Describe the structural and functional organization of the hypothalamus and the pituitary and explain their relationship </li></ul><ul><li>Discuss the locations and structures of the thyroid, parathyroid, and adrenal glands as well as the thymus and the endocrine part of the pancreas. </li></ul><ul><li>List the hormones (and their function) produced by these glands. </li></ul><ul><li>Briefly review the results of abnormal hormone production </li></ul>
    2. 2. Endocrine System Overview <ul><li>Ductless glands produce hormones </li></ul><ul><li>Gland may be entire organ or interspersed bits of tissue </li></ul><ul><li>Chemical classification of hormones </li></ul><ul><li>Target tissues are identified by receptors </li></ul>
    3. 3. Hypothalamus <ul><li>Control Center for internal environment </li></ul><ul><li>Regulates nervous and endocrine systems via 3 mechanisms: </li></ul><ul><ul><li>ANS centers exert nervous control on adrenal medulla </li></ul></ul><ul><ul><li>ADH and Oxytocin production </li></ul></ul><ul><ul><li>Regulatory hormone production (RH and IH) controls pituitary gland directly and all other endocrine glands indirectly </li></ul></ul>Fig 19-3
    4. 4. Pituitary Gland (= Hypophysis) <ul><li>Structure: </li></ul><ul><ul><li>Infundibulum - connection to hypothalamus </li></ul></ul><ul><ul><li>In the sella turcica </li></ul></ul><ul><ul><li>Two parts with an embryonic double origin </li></ul></ul><ul><li>Posterior Pituitary = neurohypophysis Storage shed for ADH and Oxytocin (produced in ?) </li></ul><ul><li>Anterior Pituitary = adenohypophysis production of 7 peptide hormones, see fig 19.5 </li></ul><ul><li>Histology </li></ul>Fig 19-4
    5. 5. Hypophyseal Portal System <ul><li>Portal systems: two capillary networks in serial arrangement Advantage? </li></ul><ul><li>Named after their destination: . . . </li></ul><ul><li>Portal veins: blood vessels that link two capillary networks </li></ul>Fig 19-6
    6. 6. Thyroid Gland <ul><li>Anterior surface of trachea just inferior of thyroid cartilage (or Adam’s apple) </li></ul><ul><li>Two lobes connected by isthmus </li></ul><ul><li>Microscopic thyroid follicles produce thyroid hormone </li></ul><ul><li>C Cells - produce calcitonin (  Ca 2+ ) </li></ul>Fig 19-7
    7. 7. Thyroid Gland Function <ul><li>Thyroxin (T4) and triiodothyronine (T3)  speed up metabolic rate </li></ul><ul><li>Calcitonin  lowers blood Ca 2+ levels </li></ul><ul><li>Thyroid pathologies: Hyper- and Hypothyroidism </li></ul>Goiter Exophthalmus
    8. 8. Hyperthyroidism Hypothyroidism Slowing of mind and body
    9. 9. Four Parathyroid Glands <ul><li>Parathyroid hormone (PTH; sometimes also called parathormone) </li></ul><ul><li>Function: antagonist to Calcitonin </li></ul>Fig 19-9 4 tiny glands embedded in the back of the thyroid (superior and inferior)
    10. 10. Thymus Gland <ul><li>Inside thoracic cavity immediately posterior to sternum above the heart </li></ul><ul><li>Most active in infancy and childhood - Largest just before puberty </li></ul><ul><li>Thymosin - enhances lymphocyte production and competence. (important for immune system) </li></ul>
    11. 11. Adrenal or Suprarenal Gland <ul><li>Cortex: corticosteroid production aldosterone, cortisol, sexhormone </li></ul><ul><li>Medulla: modified sympathetic ganglion produces adrenaline and noradrenaline ( parallels sympathetic division of ANS) </li></ul><ul><li>Histology </li></ul>Fig 19-10
    12. 12. Pancreas <ul><li>Part of endocrine and digestive systems. (99% exocrine) </li></ul><ul><li>Pancreatic islets or islets of Langerhans </li></ul><ul><ul><li> cells: glucagon (  blood sugar levels by stimulating liver to convert glycogen to glucose) </li></ul></ul><ul><ul><li> cells: insulin (  blood sugar levels by causing the cells to take up glucose for use by the mitochondria) </li></ul></ul><ul><ul><li> cells: somatostatin </li></ul></ul>The End