Endocrine 1


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Endocrine 1

  1. 1. Endocrine Jim Pierce Bi 145b Lecture 10, 2009-10
  2. 2. Endocrine System <ul><li>The endocrine system is concerned with “internal secretions” </li></ul><ul><li> “ endo-” “-crine” </li></ul><ul><li>What makes up the endocrine system? </li></ul><ul><li>(Actually… quite a difficult question) </li></ul>
  3. 3. Endocrine System <ul><li>Distance of Hormone Action </li></ul><ul><ul><li>Autocrine </li></ul></ul><ul><ul><li>Paracrine </li></ul></ul><ul><ul><li>Endocrine </li></ul></ul><ul><li>We typically leave out “local” hormones </li></ul><ul><li>The grey area occurs because no hormone is purely local. </li></ul>
  4. 4. Endocrine System <ul><li>The classic members: </li></ul><ul><ul><li>Hypothalamus and Pituitary Gland </li></ul></ul><ul><ul><li>Pineal Gland </li></ul></ul><ul><ul><li>Endocrine Pancreas </li></ul></ul><ul><ul><li>Thyroid </li></ul></ul><ul><ul><li>Parathyroids </li></ul></ul><ul><ul><li>Adrenals </li></ul></ul><ul><ul><li>Gonads </li></ul></ul>
  5. 5. Endocrine System <ul><li>The “classic members” are useful for learning </li></ul><ul><ul><li>They are important </li></ul></ul><ul><ul><li>They provide order to learning </li></ul></ul><ul><ul><li>They introduce key concepts (hormonal axis) </li></ul></ul><ul><li>Remember that it is an artificial “system” </li></ul><ul><ul><li>Organ Hormones (GI, Cardiac, Pulmonary) </li></ul></ul><ul><ul><li>Cytokines (Immune Hormones) </li></ul></ul><ul><ul><li>Orphan Endocrine Cells </li></ul></ul>
  6. 6. Endocrine Key Concepts <ul><li>Key Concept One: </li></ul><ul><li>For each hormone, what is the target cell and its receptor? </li></ul><ul><ul><li>Single or Multiple Target Cells </li></ul></ul><ul><ul><li>Single or Multiple Receptors </li></ul></ul>
  7. 7. Endocrine Key Concepts <ul><li>Key Concept Two: </li></ul><ul><li>What is the site of hormone release and its pathway to target tissue? </li></ul><ul><ul><li>Focal: Hypothalamus  Pituitary </li></ul></ul><ul><ul><li>Global: Thyroid Hormone  Body </li></ul></ul>
  8. 8. Endocrine Key Concepts <ul><li>Key Concept Three: </li></ul><ul><li>What effects do secretion, excretion, and degradation have on hormone levels? </li></ul><ul><ul><li>Steady State Disequilibrium </li></ul></ul>
  9. 9. Endocrine Key Concepts <ul><li>Key Concept Four: </li></ul><ul><li>What computational structures exist to control and regulate hormonal levels? </li></ul><ul><ul><li>AXIS </li></ul></ul><ul><ul><li>Other Control Structures </li></ul></ul>
  10. 10. Endocrine Key Concepts <ul><li>Axis: </li></ul><ul><li>A linear control structure consisting of a series of cells each secreting one hormone to stimulate the subsequent cell. </li></ul>
  11. 11. Endocrine Key Concepts <ul><li>Examples of Axes: </li></ul><ul><ul><li>Hypothalamic – Pituitary – Adrenal </li></ul></ul><ul><ul><li>Hypothalamic – Pituitary – Thyroid </li></ul></ul><ul><ul><li>Hypothalamic – Fat axis </li></ul></ul><ul><ul><li>Renin – Angiotensin – Aldosterone </li></ul></ul>
  12. 12. Endocrine Key Concepts <ul><li>Key Concept Five: </li></ul><ul><li>What other hormones act on similar targets with similar effects? </li></ul><ul><ul><li>Redundancy </li></ul></ul><ul><ul><li>Multiplicity </li></ul></ul>
  13. 13. Endocrine Key Concepts <ul><li>Key Concept Six: </li></ul><ul><li>How do these different hormones affect body metabolism? </li></ul><ul><ul><li>Free Body Diagram </li></ul></ul>
  14. 14. Endocrine Key Concepts <ul><li>It’s important to keep these ideas in mind when thinking about the endocrine system </li></ul>
  15. 15. Endocrine Pancreas <ul><li>The majority of the pancreas is a secretory exocrine gland </li></ul><ul><li>A minority of the pancreas is an secretory endocrine gland </li></ul><ul><li>These collections of endocrine cells are called the Islets of Langerhans </li></ul>
  16. 16. Endocrine Pancreas
  17. 17. Endocrine Pancreas <ul><li>Islets contain: </li></ul><ul><ul><li>Alpha Cells - Glucagon (15-20%) </li></ul></ul><ul><ul><li>Beta Cells - Insulin (65-80%) </li></ul></ul><ul><ul><li>Delta Cells - Somatostatin (3-10%) </li></ul></ul><ul><ul><li>PP Cells - Pancreatic Polypeptide (< 1%) </li></ul></ul><ul><ul><li>Epsilon Cells – Ghrelin? (<0.5%) </li></ul></ul>
  18. 18. Alpha Cells - Glucagon
  19. 19. Beta Cells - Insulin
  20. 20. Delta Cells - Somatostatin
  21. 21. Endocrine Pancreas
  22. 22. Hypothalamus <ul><li>Anatomy and Microanatomy </li></ul><ul><li>Lives in the Diencephalon </li></ul><ul><li>Inferomedial to Thalamus </li></ul>
  23. 23. Hypothalamus <ul><li>Anatomy and Microanatomy </li></ul>
  24. 24. Hypothalamus <ul><li>Hypothalamic Nuclei </li></ul>
  25. 25. Hypothalamus <ul><li>Thyrotropin-releasing hormone (TRH) </li></ul><ul><li>Gonadotropin-releasing hormone (GnRH) </li></ul><ul><li>Growth hormone-releasing hormone (GHRH) </li></ul><ul><li>Corticotropin-releasing hormone (CRH) </li></ul><ul><li>Somatostatin </li></ul><ul><li>Dopamine </li></ul>
  26. 26. Pitutary Gland <ul><li>Anatomy and Microanatomy </li></ul><ul><li>Lives in the Skull Base in its own compartment </li></ul><ul><li>Sella Turcica </li></ul>
  27. 27. Pituitary Gland <ul><li>Sella Turcica (Turkish Saddle) </li></ul><ul><li>Located in Sphenoid Bone </li></ul>
  28. 28. Pituitary Gland <ul><li>Gross View </li></ul>Posterior Anterior
  29. 29. Pituitary Gland <ul><li>The “gland” consists of two grossly identifiable parts </li></ul><ul><li>Anterior Pituitary </li></ul><ul><li>Posterior Pituitary </li></ul>
  30. 30. Pituitary Gland <ul><li>Microscopically, there are many more parts </li></ul><ul><li>The functional division between anterior and posterior stays true. </li></ul>Posterior Anterior
  31. 31. Pituitary Gland <ul><li>Posterior Pituitary </li></ul><ul><ul><li>Has Neurons </li></ul></ul><ul><ul><li>Cell Bodies are in hypothalamus </li></ul></ul><ul><ul><li>Synapses with Blood Vessels </li></ul></ul>
  32. 32. Pituitary Gland <ul><li>Anterior Pituitary </li></ul><ul><ul><li>Has “Endocrine” Cells </li></ul></ul><ul><ul><li>Looks and Acts like a Gland </li></ul></ul><ul><ul><li>Not Innervated </li></ul></ul>
  33. 33. Pituitary Gland <ul><li>The pituitary “hangs” off the hypothalamus </li></ul><ul><li>Blood Supply is in three steps </li></ul><ul><li>Arterial supply arrives at the hypothalamus via the Circle of Willis </li></ul>
  34. 34. Pituitary Gland <ul><li>Next, the venous drainage from the Hypothalamus goes to the Pituitary </li></ul><ul><li>This is called the “Portal System” </li></ul><ul><li>Just like in the gut and liver </li></ul>
  35. 35. Pituitary Gland <ul><li>After passing through the Portal System and carrying hypothalamic hormones to the pituitary </li></ul><ul><li>The venous blood, carrying pituitary hormones, returns to the systemic veins </li></ul>
  36. 36. Pituitary Gland <ul><li>Just like the portal system of the gut gives the liver first crack at “gut absorbed” stuff </li></ul><ul><li>This portal system gives the pituitary first crack at secreted hypothalamic hormones </li></ul>
  37. 37. Pituitary Gland
  38. 38. Hypothalamus and Pituitary Gland <ul><li>Together, they compare and contrast the classic endocrine and neuroendocrine systems </li></ul><ul><li>Neuroendocrine System: Nerves release Neurotransmitters into blood </li></ul><ul><li>Endocrine System: Hormones from one part of the body go to another </li></ul>
  39. 39. Posterior Pituitary <ul><li>Cell Bodies in Hypothalamus </li></ul><ul><ul><li>Supraoptic and Paraventricular Nuclei </li></ul></ul><ul><li>Axons in the Pars tuberalis </li></ul><ul><li>“ Synapse” in the Pars nervosa </li></ul>
  40. 40. Posterior Pituitary <ul><li>Histologically, it’s not that interesting </li></ul><ul><li>(Looks like nerves) </li></ul>
  41. 41. Anterior Pituitary <ul><li>Cell Bodies look like “Glands” </li></ul>
  42. 42. Anterior Pituitary <ul><li>Depending on the stain </li></ul><ul><li>Some cells like stain: Chromophils </li></ul><ul><ul><li>Acidophils </li></ul></ul><ul><ul><li>Basophils </li></ul></ul><ul><ul><li>Neutrophils </li></ul></ul><ul><li>Some cells don’t: Chromophobes </li></ul>
  43. 43. Anterior Pituitary <ul><li>Why stain differently? </li></ul><ul><li>Each Cell produces one and only one hormone. </li></ul><ul><li>Different hormone peptides have different chemical properties </li></ul>
  44. 44. Pituitary Development <ul><li>The two regions of pituitary have separate origins </li></ul><ul><ul><li>Anterior = Endoderm </li></ul></ul><ul><ul><li>Posterior = Neuroectoderm </li></ul></ul>
  45. 45. Pituitary Gland
  46. 46. Pituitary Gland <ul><li>Anterior lobe (adenohypophysis) </li></ul><ul><ul><li>GH Growth hormone </li></ul></ul><ul><ul><li>PRL Prolactin </li></ul></ul><ul><ul><li>ACTH Adrenocorticotropic hormone </li></ul></ul><ul><ul><li>TSH Thyroid-stimulating hormone </li></ul></ul><ul><ul><li>FSH Follicle-stimulating hormone </li></ul></ul><ul><ul><li>LH Luteinizing hormone </li></ul></ul>
  47. 47. Pituitary Gland <ul><li>Posterior lobe (neurohypophysis) </li></ul><ul><ul><li>Oxytocin </li></ul></ul><ul><ul><li>Antidiuretic hormone (ADH) </li></ul></ul>
  48. 48. Pineal Gland <ul><li>Pineal gland </li></ul><ul><li>Early Chordates histologically resembles eye </li></ul><ul><li>Hypothesized to regulate day-night cycles </li></ul>
  49. 49. Pineal Gland <ul><li>Located between superior colliculi </li></ul><ul><li>In Humans 8 mm in size </li></ul>
  50. 50. Pineal Gland <ul><li>Located inside Meninges </li></ul><ul><li>Very Vascular </li></ul>
  51. 51. Pineal Gland <ul><li>Secretes Melatonin </li></ul>
  52. 52. Thyroid Gland <ul><li>Lives in the Neck </li></ul><ul><li>Derived from the Branchial Arches </li></ul>
  53. 53. Thyroid Gland <ul><li>Consists of Lobes </li></ul><ul><ul><li>Right and Left </li></ul></ul><ul><ul><li>Isthmus </li></ul></ul><ul><ul><li>Pyramidal </li></ul></ul>
  54. 54. Thyroid Gland <ul><li>Foramen Cecum inside the mouth develops into a small diverticulum </li></ul><ul><li>This is dragged towards the chest during body folding </li></ul>
  55. 55. Thyroid Gland <ul><li>Foramen Cecum lies medial to 1 st and 2 nd arches </li></ul>
  56. 56. Thyroid Gland
  57. 57. Branchial Arches <ul><li>Foramen Cecum becomes Thyroid </li></ul><ul><li>Third and Fourth Arches become Parathyroids </li></ul><ul><li>Third Arch becomes Thymus </li></ul>
  58. 58. Thyroid Gland <ul><li>Pyramidal Lobe is the “remnant” </li></ul><ul><li>Right and Left Lobes are the “main gland” </li></ul>
  59. 59. Thyroid Gland <ul><li>Heavily Vascular (Like most glands) </li></ul><ul><li>Arterial Supply and Venous Drainage from Branchial Arches </li></ul>
  60. 60. Thyroid Gland <ul><li>The gland consists of Thyroid Follicles </li></ul><ul><li>Cuboidal Epithelium </li></ul><ul><li>Central Colloid </li></ul><ul><li>Supportive Stroma </li></ul><ul><li>Parafollicular Cells </li></ul>
  61. 61. Thyroid Gland <ul><li>Thyroid Hormone </li></ul><ul><ul><li>Thyroxine (T4) </li></ul></ul><ul><ul><li>Triiodothyronine (T3) </li></ul></ul><ul><li>C-Cells </li></ul><ul><ul><li>Calcitonin </li></ul></ul>
  62. 62. Parathyroids <ul><li>Aptly named glands that live around thyroid: </li></ul>
  63. 63. Branchial Arches <ul><li>Foramen Cecum becomes Thyroid </li></ul><ul><li>Third and Fourth Arches become Parathyroids </li></ul><ul><li>Third Arch becomes Thymus </li></ul>
  64. 64. Parathyroid Gland
  65. 65. Parathyroid <ul><li>Secretes Parathyroid hormone (PTH) </li></ul>
  66. 66. Adrenal Glands <ul><li>These are paired suprarenal glands </li></ul><ul><li>Embryologically: </li></ul><ul><li>Cortex forms first </li></ul><ul><ul><li>Gonadal Ridge </li></ul></ul><ul><li>Medulla forms second </li></ul><ul><ul><li>Neural Crest Origin </li></ul></ul>
  67. 67. Adrenal Glands <ul><li>Histologically, </li></ul><ul><li>It’s quite easy to see the difference between CORTEX and MEDULLA </li></ul>
  68. 68. Adrenal Glands
  69. 69. Adrenal Cortex This should remind you of the kidney
  70. 70. Adrenal Medulla
  71. 71. Adrenal Glands <ul><li>Adrenal cortex </li></ul><ul><ul><li>Glucocorticoids - cortisol </li></ul></ul><ul><ul><li>Mineralocorticoids - aldosterone </li></ul></ul><ul><ul><li>Androgens (including testosterone) </li></ul></ul><ul><li>Adrenal medulla </li></ul><ul><ul><li>Epinephrine </li></ul></ul><ul><ul><li>Norepinephrine </li></ul></ul>
  72. 72. Gonads <ul><li>We’ll save these for Reproduction Endocrinology </li></ul>
  73. 73. Orphan Endocrine Cells <ul><li>APUD Cells </li></ul><ul><li>Amine Precursor Uptake and Decarboxylation A P U D </li></ul><ul><li>Generate tissue and organ levels of “Traditional Neurotransmitters” </li></ul>
  74. 74. Orphan Endocrine Glands <ul><li>Heart </li></ul><ul><ul><li>Atrial-natriuretic peptide (ANP) </li></ul></ul><ul><li>Stomach and intestines </li></ul><ul><ul><li>Gastrin </li></ul></ul><ul><ul><li>Somatostatin </li></ul></ul><ul><ul><li>Secretin </li></ul></ul><ul><ul><li>Cholecystokinin (CCK) </li></ul></ul><ul><ul><li>Neuropeptide Y </li></ul></ul><ul><li>Liver </li></ul><ul><ul><li>Insulin-like growth factor </li></ul></ul><ul><ul><li>Angiotensinogen </li></ul></ul><ul><ul><li>Thrombopoietin </li></ul></ul>
  75. 75. Orphan Endocrine Glands <ul><li>Kidney </li></ul><ul><ul><li>Renin </li></ul></ul><ul><ul><li>Erythropoietin (EPO) </li></ul></ul><ul><ul><li>Calcitriol </li></ul></ul><ul><li>Skin </li></ul><ul><ul><li>Calciferol (vitamin D3) </li></ul></ul><ul><li>Adipose tissue </li></ul><ul><ul><li>Leptin </li></ul></ul>
  76. 76. Questions?