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