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Endocrine System

Endocrine System. Organization of endocrine system: endocrine glands and endocrine cells Structure characteristic of endocrine gland: hormone paracrine target organ target cell receptor Protein-secreting cells: Steroid-secreting cells:. Thyroid Gland. Capsule lobules.

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Endocrine System

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  1. Endocrine System Organization of endocrine system: endocrine glands and endocrine cells Structure characteristic of endocrine gland: • hormone • paracrine • target organ • target cell • receptor • Protein-secreting cells: • Steroid-secreting cells:

  2. Thyroid Gland Capsule lobules

  3. ⅠFollicles 1. Follicular epithelial cells: LM EM: colloid-containing vesicles 2. colloid: thyroglobulin, thyroxine: (tetraiodothyronine, T4) triiodothyronine, T3)

  4. Synthesis of thyroxines • triiodothyronine (T3) & tetraiodothyronine (T4): • Synthesize thyroglobulin in RER • (RER,G) → secreting granules → thyroglobulin (colloid) • 2. Uptake of iodide and iodation of thyroglobulin • Iodide → iodide pump→ iodide oxidation in cytoplasm • → colloid → bound to tyrosine residues of thyroglobulin → • iodated thyroglobulin. • 3. I-thyroglobulin resorption and decomposition • iodated thyroglobulin → phagocytosis → phagosomes → • LYS →hydrolyze → T3 & T4. • 4. Releasing of T3 & T4

  5. Function of T3, T4: 1. elevates the basal metabolic rate. 2. body growth and nervous system development 3. Cretins: Retardation mental and physical development. * Dwarf: growth hormone

  6. function of follicular epithelial cells

  7. Ⅱ parafollicular cells (C cells) : LM: EM: Function: calcitonin

  8. Adrenal Gland • Adrenal cortex • Adrenal medulla:

  9. 1. Adrenal cortex (1) zona glomerulosa: LM: function: mineralocorticoid (aldosterone) (2) zona fasiculata: LM: EM: function: glucocorticoid (3) zona reticularis: LM: androgen, less numerous glucocorticoid and estrogen

  10. 1. Zona glomerulosa: Cells are arranged in clusters beneath the capsule. The secretion, the mineralocorticoids (e.g. aldosterone), participates in electrolyte balance regulation.

  11. 2. Zona fasciculata: takes about 65% of cortex. The typical steroid-secreting cells in the body are arranged in straight cords, and run perpendicularly to the capsule.

  12. 3. Zona reticularis: Adjacent to medulla with obscure outline. Cells are arranged in net-like structure and contain more lipofuscin pigment granules.

  13. 2. adrenal medulla: chromaffin cells, ganglion nerve cells, centre vein function: adrenaline, noradrenaline

  14. Pituitary Gland (Hypophysis) • adenohypophysis • neurohypophysis

  15. hypophysis adenohypophysis neurohypophysis Pars nervosa infundibulum Pars tuberalis Pars intermedia Pars distalis Median eminence Infundibular process

  16. hypophysis

  17. 1. Adenohypophysis 1.1 pars distalis (anterior lobe) (1) chromophil cells ①acidophilic cells: LM: A. somototroph (growth hormone, GH) B. mammotroph (mammotropin) ②basophilic cells: LM: A. thyrotroph: thyroid stimulating hormone (TSH) B. gonadotroph: follicle stimulating hormone, FSH (female, male) luteinizing hormone, LH (female, male) interstitial cell stimulating hormone, (ICSH) C. corticotroph (adrenocorticotrophic hormone, ACTH) lipotrophic hormone ,LPH (2) chromophobe cells: LM: EM:

  18. 3. pars tuberalis abundant longitudinal capillaries chromophobe cells and small amounts of acido-basophilic cells, the later secretes FSH and LH 2. pars intermedia: follicles, chromophobe cells and basophilic cells melanocyte stimulating hormone, MSH

  19. 4. Blood Supply of Adenohypophysis superior hypophyseal artery fist capillary loops hypophyseal portal venule second capillary loops Hypophyseal portal system inferior hypophyseal vein

  20. 2. Neurohypophysis the organization: unmyelinated never fibers and neuroglial cells • Herring body (LM, EM) • pituicyte • antidiuretic hormone (ADH) , vassopressin, • oxytocin (OT)

  21. Pineal Body The organization: pinealocytes, neuroglial cells and unmyelinated never fibers • Pinealocyte : • LM: brain sand • Function: melatonin

  22. Diffuse Neuroendocrine System • Amine Precursor Uptake and Decarboxylation Cells so called APUD cells diffuse neuroendocrine system:

  23. adrenal cortex

  24. ultrastructure of steroid-secreting cells

  25. pars distalis of adenohypophysis

  26. neurohypophysis

  27. 轴突内的分泌颗粒 内皮 Herring bodies in EM

  28. 松果体细胞 神经胶质细胞 脑砂 毛细血管 毛细血管 pineal body

  29. pinealocytes and brain sand

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