Endocrine system summary


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Endocrine system summary

  1. 1. ENDOCRINE SYSTEM<br />Exerts chemical control over the human body<br />Maintains homeostasis <br />Acts with nervous system to coordinate the body's activities<br />Uses chemical messengers called hormones that are transported by the circulatory system (blood)<br />TYPES OF HORMONES<br /><ul><li>Steroid
  2. 2. Amino acid
  3. 3. Protein</li></ul>HYPOTHALAMUS<br /><ul><li>Inferior part of the diencephalon
  4. 4. Control center of all autonomic regulatory activities of the body
  5. 5. Main function of the hypothalamus is homeostasis
  6. 6. HOMEOSTASIS - maintaining the body’s internal environment</li></ul>Plays a major role in controlling the secretions from the Pituitary gland<br />Sends neural and chemical signals to the pituitary gland<br />CHEMICAL SIGNALS<br />Releasing Hormones<br /><ul><li>main purpose is to control the release of another hormone
  7. 7. Stimulates the release of hormones
  8. 8. Capillary bed, portal vein, receptors.</li></ul>Inhibitory Hormones<br /><ul><li>inhibits release of hormones from another structure
  9. 9. convey the hormones through the pituitary stalk into the anterior pituitary. </li></ul>*NEGATIVE FEEDBACK<br /><ul><li>when the particular level of concentration of a particular hormone reaches a certain level in the body, the endocrine gland that secreted the hormone in inhibited and the secretion of that hormone either ceases or decreases significantly
  10. 10. helps to control the concentrations of a number of hormones in the body</li></ul>PITUITARY GLAND (Hypophysis)<br />PITUITARY GLAND<br /><ul><li>a pea-sized, compound endocrine gland, centrally located at the base of the brain.
  11. 11. Sella turcica– saddle-shaped depression of the sphenoid bone where lies the pituitary gland
  12. 12. A short stalk, the infundibulum, and a vascular network connect the pituitary gland to the hypothalamus.
  13. 13. “master organs” of the ES (with the Hypothalamus) </li></ul>2 FUNCTIONAL COMPONENTS<br />Anterior Pituitary (Adenohypophysis)<br /><ul><li>The glandular epithelial tissue
  14. 14. The cells are organized in clumps and cords separated by fenestrated sinusoidal capillaries.
  15. 15. Regulates other endocrine glands and some non-endocrine tissues
  16. 16. 3 derivatives of Rathke’s pouch:
  17. 17. Pars distalis (distal lobe)
  18. 18. Pars intermedia (intermediate lobe)
  19. 19. Pars tuberalis (tuberal lobe)</li></ul>Posterior Pituitary (Neurohypophysis)<br /><ul><li>The neural (secretory) tissue
  20. 20. Presence of highly branched glial cells called pituicytes that resemble astrocytes and are the most abundant cell type in the posterior pituitary; serves a supporting role in the CNS
  21. 21. NOT an endocrine gland; stores and releases secretory products from the hypothalamus
  22. 22. 3 components:
  23. 23. Neural lobe (Pars nervosa, Infundbular process)
  24. 24. Pituitary stalk (Infundibular stem)
  25. 25. Median Eminence</li></ul>*Hormones – See Hormones Page<br />THYROID GLAND <br /><ul><li>Located in the anterior neck region adjacent to the larynx and trachea
  26. 26. Consists of two lateral lobes united by an isthmus
  27. 27. Composed of connective tissue septa and follicles </li></ul>MAIN FUNCTION<br /><ul><li>Synthesize the thyroid hormones </li></ul>Thyroxine (Tetra – iodothyronine or T4)<br />Tri – iodothyronine (T3)<br />Calcitonin <br />STROMA <br /><ul><li>Thin loose areolar connective tissue capsule that forms connective tissue septa</li></ul>FOLLICULAR EPITHELIUM <br /><ul><li>Surrounds each follicle
  28. 28. Composed of reticular fibers and network of capillaries
  29. 29. Can be simple squamous, cuboidal, or low columnar epithelium</li></ul>THYROID FOLLICLE <br />Structural unit of thyroid gland <br />Roughly spherical cyst-like compartment<br />Wall formed by follicular epithelium<br />Central cavity contains a gelatinous substance called colloid<br /><ul><li>Surrounded by 2 types of cells
  30. 30. a. Follicular cells
  31. 31. Also called Principal cells
  32. 32. Most numerous cell type
  33. 33. Cuboidal in shape with spherical nucleus
  34. 34. Secretion and synthesis of T3 and T4 </li></ul>b. Parafollicular cells <br /><ul><li>Also called C (clear) cells
  35. 35. Larger than follicular cells
  36. 36. Can occur either alone or in clumps
  37. 37. Synthesize and secrete calcitonin </li></ul>THYROID HORMONES <br /><ul><li>Thyroxine (T4) and Tri – iodothyronine (T3)
  38. 38. Responsible for growth,cell differentiation and control of the basal metabolic rate and oxygen consumption in cells
  39. 39. Affect protein, lipid, and carbohydrate metabolism
  40. 40. Calcitonin
  41. 41. Lower blood calcium levels through inhibition of bone resorption
  42. 42. Secretion is triggered by elevation of blood calcium concentration </li></ul>PARATHYROID GLAND <br /><ul><li>Four small glands
  43. 43. Usually embedded in the thyroid capsule
  44. 44. Derived from the pharyngeal pouches
  45. 45. Consists of 2 cell types</li></ul>a. Chief Cells<br /><ul><li>Synthesis and secretion of parathyroid hormone (parathormone)</li></ul>b. Oxyphil Cells<br /><ul><li>Larger than chief cells
  46. 46. Found singly or in small groups
  47. 47. Less numerous than chief cells</li></ul>PARATHYROID HORMONE ( Parathormone)<br /><ul><li>Increases blood calcium</li></ul>*See Hormones Page for additional information<br />ADRENAL GLAND<br />Paired organs<br />Flattened structure with half – moon shape<br />Surrounded by dense irregular connective tissue – reticular fibers for support<br />Embedded in adipose tissue<br />2 concentric layers:<br /><ul><li>Adrenal cortex
  48. 48. Adrenal medulla</li></ul>Cells of both layers are grouped in cords along capillaries<br />Dense CT capsule sends thin septa to the interior of the gland – trabeculae<br />ADRENAL CORTEX<br />Cells contain numerous lipid droplets<br />Spongyocytes <br />Cells that secrete glucocorticoids, mineralocorticoids, and gonadocorticoids <br />Has 3 concentric layers with fenestrated capillaries<br /><ul><li>Zona Glomarulosa
  49. 49. Occupy 15% of the cortex
  50. 50. Immediately beneath the capsule
  51. 51. Columnar or pyramidal cells
  52. 52. Arranged in closely packed, rounded, arched cords, or small clumps
  53. 53. Secrete hormone mineralocorticoid - aldosterone
  54. 54. Zona Fasciculata
  55. 55. Occupy 65% of the cortex
  56. 56. Intermediate zone
  57. 57. Polyhedral, often binucleated cells with lipid droplets in their cytoplasm
  58. 58. Cells are also called spongyocytes due to vacuolization
  59. 59. Arranged in one or two – cell thick straight cords
  60. 60. Secrete hormone glucocorticoid - cortisol
  61. 61. Zona Reticularis
  62. 62. Occupy 7% of the cortex
  63. 63. Innermost layer – lies between zona fasciculata and medulla
  64. 64. Smaller cells disposed in irregular cords forming an anastomosing network
  65. 65. Presence of lipofuscin pigment granules – large and numerous
  66. 66. Irregularly shaped cells with pyknotic nuclei – suggesting cell death
  67. 67. Arranged in cords or clumps
  68. 68. Secrete hormone sex hormones or androgens</li></ul>*GO FIND REX FOR A GOOD SEX*<br />*Hormones – see Hormones page<br />ADRENAL MEDULLA<br /><ul><li>Lies in the center of the adrenal gland
  69. 69. Composed of polyhedral cells
  70. 70. Arranged in cords or clumps, supported by reticular fiber network
  71. 71. Composed of chromaffin cells
  72. 72. Secretes catecholamines – Epinephrine and Norepinephrine
  73. 73. Contains sympathetic ganglion cells</li></ul>Chromaffin Cells<br /><ul><li>A neuroendocrine cell
  74. 74. Release neurotransmitter into systemic circulation for systemic effects on multiple organs
  75. 75. Contains NE and E cells
  76. 76. E cells
  77. 77. Characterized by containing small granules
  78. 78. Store epinephrine
  79. 79. NE cells
  80. 80. Characterized by larger granules
  81. 81. Contains dense cores giving an appearance of eccentric “bulls - eyes”
  82. 82. More intense chromaffin reaction
  83. 83. Store norepinephrine </li></ul>*Hormones – See Hormones Page<br />FEMALE REPRODUCTIVE SYSTEM<br />OVARIES<br /><ul><li>Surface is covered by simple squamous or cuboidal epithelium called germinal epithelium
  84. 84. Under the covered surface is the tunica albuginea made of dense irregular connective tissue and responsible for whitish color of ovary
  85. 85. Below that tunica albuginea is the cortex of the ovary where there is predominance of ovarian follicles
  86. 86. Deep in the cortex is highly vascularized connective tissue core of ovary, medulla
  87. 87. Hormones: Estrogen and Progesterone</li></ul>ESTROGEN<br /><ul><li>Manufactured mostly in ovaries by developing egg follicles
  88. 88. In addition, produced by the corpus luteum, placenta, liver, breasts and adrenal glands in smaller quantities
  89. 89. Essential to the menstrual cycle
  90. 90. Prepares uterus for pregnancy
  91. 91. Enriching and thickening of endometrium
  92. 92. Contributes to the development of secondary characteristics
  93. 93. Breasts, widened pelvis, increased body fat in buttocks, thigh and hip region
  94. 94. Less facial hair and smoother skin
  95. 95. Luteinizing hormone (LH) and Follicle stimulating hormone (FSH) help to control production of estrogen</li></ul>PROGESTERONE<br /><ul><li>Responsible for the changes in the endometrium in the second half of the menstrual cycle
  96. 96. For fertility and pregnancy
  97. 97. Prepare the endometrium for implantation of fertilized egg and its development
  98. 98. Maintain the uterus throughout pregnancy
  99. 99. Low progesterone hormones have negative influences on your body, fertility, pregnancy and can even lead to an expelling of a fertilized egg</li></ul>EGG CELL<br /><ul><li>The cell substance is known as the yolk or oöplasm
  100. 100. The nucleus as the germinal vesicle and the nucleolus as the germinal spot
  101. 101. The human ovum is surrounded by a number of egg envelopes:
  102. 102. Vitelline membrane
  103. 103. A thin, inner transparent layer secreted by the ovum itself
  104. 104. Zona pellucid
  105. 105. A thick middle layer which is transparent and non - cellular
  106. 106. Corona radiate
  107. 107. An outer, thicker coat formed of radially elongated follicular cells.
  108. 108. Between the vitelline membrane and zona pellucida, there is a narrow space called perivitelline space </li></ul>MALE REPRODUCTIVE SYSTEM<br />TESTES<br />Located in the scrotum<br />Secrete hormone known as androgen; most important of which is testosterone <br />Have an exocrine part, Seminiferous tubules (tightly coiled) and endocrine part, intersitial or Leydig cells (clusters) Leydig cells<br />Synthesise and secrete testosterone<br />Testosterone increases sharply at puberty<br />Essential for the production of sperm<br />Production of testosterone is controlled by the release of luteinizing hormone (LH) <br />Located in the interstitial tissue between the convuluted seminiferous tubules<br />Occurs in clusters, which are variable in size and richly supplied by capillaries<br />Its cytoplasm is strongly acidophilic and finely granular<br />The nucleus is large, round and often located eccentric in the cell <br />GENERAL EFFECTS OF TESTOSTERONE<br /><ul><li>Anabolic</li></ul>Growth of muscle mass and strength<br />Increased bone density and strength<br />Linear growth<br />Bone maturation<br /><ul><li>Androgenic (Virilizing)
  109. 109. Maturation of sex organs (part. Penis)
  110. 110. Formation of scrotum in the fetus
  111. 111. Deepening of voice (sec. sex charac.)
  112. 112. Growth of beard and axillary hair (sec. sex charac.)</li></ul>Hypothalamus<br />GnRH<br />Pituitary<br />LH<br />Testes<br />Testosterone<br />SERTOLI CELLS<br />‘Nurse’ cell of the testes<br />Part of the seminiferous tubule<br />Activated by follicle-stimulating hormone and has FSH-receptor on its membranes.<br />Estradiol and Inhibin – hormone secreted<br />Estradiol<br />Prevent apoptosis (death of cells) of germ cells <br />Inhibin<br />Inhibit production of FSH<br />PINEAL GLAND<br /><ul><li>Also called Epiphysis Cerebri
  113. 113. A pine cone shaped gland
  114. 114. Produces several important hormones including melatonin
  115. 115. Melatonin influences sexual development and sleep-wake cycles
  116. 116. Composed of cells called pinealocytes and cells of the nervous system called glial cells
  117. 117. Connects the endocrine system with the nervous system in that it converts nerve signals from the sympathetic system of the peripheral nervous system into hormone signals
  118. 118. Also contains sand - well - brain sand or corpora arenacea
  119. 119. Calcium-containing concretions in the pineal parenchyma
  120. 120. Increase in size and number with age
  121. 121. Radio opaque
  122. 122. Provide a good midline-marker
  123. 123. 2 cell types
  124. 124. Pinealocytes
  125. 125. 95% of the cells
  126. 126. Large, light and round nuclei
  127. 127. Secretions: cocktail substances
  128. 128. May decrease secretory activity in most other endocrine glands
  129. 129. May delay puberty through antigonadotrophic effects
  130. 130. Astrocytes
  131. 131. Glial cells
  132. 132. Dark, elongated nuclei
  133. 133. Interstitial cells
  134. 134. Greater number in the stalk of the gland
  135. 135. Nuclei are elongated
  136. 136. Stain more deeply than those of the pinealocytes
  137. 137. Resemble the astrocytes of the brain in having long-cell process and an abundance of intermediate filaments throughout the cytoplasm
  138. 138. The most prominent secretory product of the pineal body is melatonin
  139. 139. Secretory activity in the pineal gland is stimulated by darkness and inhibited by light</li></ul>MAIN FUNCTION<br /><ul><li>Secretion of the hormone melatonin
  140. 140. Regulation of endocrine functions
  141. 141. Conversion of nervous system signals to endocrine signals
  142. 142. Causes feeling of sleepiness
  143. 143. Influences sexual development</li></ul>PIA MATER<br /><ul><li>The delicate inner layer of connective tissue that covers the brain
  144. 144. Surrounding the pineal body
  145. 145. Functions as its capsule and which sends connective tissue septa into the pineal body, subdividing it into lobules.</li></ul>THYMUS GLAND<br /><ul><li>Enclosed in a capsule and divided internally by cross-walls into many lobules (full of T-lymphocytes).
  146. 146. Lymphocytes that have passed through the thymus are transformed into T cells.
  147. 147. Lymphocytes are white blood cells that function to fight infection. There are two kinds of lymphocytes: B cells and T cells. T cells participate in identifying and destroying body cells that are infected.</li></ul>HORMONES<br /><ul><li>Thymosin
  148. 148. Activates the immune system by activating the T-Cells (T-Killer Cells; T-Helper Cells; T-Memory Cells)
  149. 149. T – Lymphocytes
  150. 150. The thymus consists of lobules full of T-lymphocytes (white blood cells associated with antibody production).
  151. 151. T-lymphocytes migrate from the bone marrow to the thymus, where they mature and differentiate until activated by antigens.</li></ul>ALIMENTARY SYSTEM<br />STOMACH<br /><ul><li>Gastrin
  152. 152. From G cells
  153. 153. Secretion of gastric acid by parietal cells
  154. 154. As stomach acidity increase, its production decreases</li></ul>Ghrelin<br />From P/D1 cells<br />Stimulate appetite<br />Secretion of growth hormone from anterior pituitary gland <br />Somatostatin<br />From D cells<br />Suppress release of gastrin, CCK, secretin <br />Reduces smooth muscle contractions<br />DUODENUM<br /><ul><li>Ssecretin
  155. 155. From S cells
  156. 156. Secretion of bicarbonate from liver, pancreas and duodenal Brunner’s gland
  157. 157. Enhances effects of CCK
  158. 158. Stops production of gastric juice
  159. 159. Cholecystokenin
  160. 160. From I cells
  161. 161. Release of digestive enzyme from pancreas
  162. 162. Release bile from gallbladder</li></ul>LIVER<br />Thrombopoietin<br />From hepatocytes<br />Stimulates megakaryocytes to produce platelets<br />Insulin Like Growth Factor (IGF)<br />From hepatocytes<br />Insulin like effects<br />Regulate cell growth and development<br />Angiotensinogen and Angiotensin<br />From hepatocytes<br />Vasoconstriction<br />Release of aldosterone from adrenal cortex dipsogen <br />PANCREAS<br />Glucagon<br />From α islet cells<br />Glycogenolysis and gluconeogenesis in liver<br />Increases blood glucose level<br />Insulin<br />From β islet cells<br />Intake of glucose<br />Glycogenesis and glycolysis<br />Lipid synthesis<br />Somatostatin<br />From δ islet cells<br />Inhibit release of insulin<br />Inhibit release of glucagon<br />Suppress the exocrine secretory action of pancreas<br />