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Introduction to Endocrine system

Kelly C Physiology exam study English 131 cards

Cards in this deck (131)

  1. 1What is a hormone?Chemical messenger synthesised within a cell and released into the blood and transported to cells where they have a specific effect
  2. 2Features of hormones (6)Synthesised by specialised cells
    Secreted directly into blood in small amts.
    Carried in blood to their site of action
    Are chemically bound to receptor at action site
    Speed up or slow down specific cellular reaction
    Broken down rapidly
  3. 3Functions of hormones (5)Maintain homeostasis
    Help body to respond to external changes
    Promote growth
    Regulate reproductive processes
    Regulate metabolism
  4. 4Endocrine system vs Nervous systemEndocrine: Hormones travel via blood to act at several targets. Distant and slower
    Nervous: Neurotransmitters act directly on single cells. Local and rapid
  5. 5Discovery of hormones: Berthold's experimentCastrated cockerels had regressed combs and wattles, normal when had transplanted testicles: Hormones produced in testes travelled via blood to distant tissue
  6. 6Discovery of Hormones: Bayliss and Starting's experimentDemonstrated existence of hormone produced in duodenum that secreted pancreatic juice. Developed concept of hormones
  7. 7Experiments to identify hormoneRemoval of tissue type to reduce its function and function restored by injecting extracts of tissue, with hormone being active principle in extract
  8. 8What does the endocrine system consist of?Endocrine clls amoing non-endocrine cells, Clusters or cords of endocrine cells forming endocrine tissues and endocrine organs.
  9. 9Function of Hypothalamus in endocrine systemRegulates secretion of hormones from the pituitary gland. Pituitary hormones control the secretion of hormones from other glands. Medulla of adrenal gland directly innervated and pancreas and parathyroid controlled by peripheral feedback
  10. 10Endocrine gladsSecrete hormones directly into capillaries
  11. 11Exocrine glandsSecrete hormones into ducts that lead into the gut or external structures
  12. 12FolliclesSingle layer of endocrine cells surrounding a hollow sphere like in Thyroid gland
  13. 13NeurohormonesProduced by neurons and secreted from nerve endings into capillaries
  14. 14Structure of peptide producing endocrine cellsProminent rough ER and secretory granules
  15. 15Structure of steroid producing endocrine cellsExtensive smooth ER, distinctive mitochondria and lipid granules
  16. 16Structure of neurosecretory cellsHave secretory granules
  17. 17Two groups of hormonesCatecholamines, peptides and thyroid hormones: synthesised from amino acids
    Steroids and Prostaglandins: Synthesised from fatty acids
  18. 18Amino acid based hormone characteristics (4) and thyroid hormones (2)Soluble in aqueous solvents, synthesised from prohormones, short half life and bind receptors on cell surface.
    Thyroid hormones: Long half life and bind nuclear receptors
  19. 19Fatty acid based hormone characteristics (4)Soluble in non polar solvents, synthesised via multiple enzyme pathways, long half life and bind to intracellular receptors
  20. 20Mineralocorticoid exampleAldosterone
  21. 21Glucocorticoidclass of corticosteroid, produced in Adrenal cortex
  22. 22Catecholamines and stimuli for secretionProduced in renal medulla. Adrenaline and noradrenaline
    Synthesised from Tyrosine
    Stimuli: Sympathetic nerve impulse
  23. 23Thyroid hormone synthesisT3 contains 3 I atoms, T4 has 4.
    Synthesised from Tyrosine amino acids incorporated in precursor Thyroglobulin. I incorporated into Tyrosine and I-Tyrosine units combine to form T3 and T4
  24. 24Peptide and Protein hormones and characteristicsComprised of amino acid chains can be small or very large. TRH 3 AAs and GH ~200
    These hormones are synthesised from precursor molecules (Proinsulin-insulin)
  25. 25Steroid hormones: Structure and groups based on C numberSynthesised from cholesterol, different hormones have different side chains attached to the same 3-6 carbon ring and 1-5 carbon ring skeleton
    C18 Estrogen
    C19 Androgen
    C21 Progestin and Corticosteroids
  26. 26CorticosteroidsMineralocorticoid - Aldosterone
    Glucocorticoid - Cortisol
    Produced in Adrenal cortex
  27. 27Prostaglandins - structure and functionSpecialised fatty acids that affect reproductive system, temperature and inflammation
  28. 28Melatonin secretionSecreted by Pineal gland, stimuli is day rhythms
  29. 29Functions of SomatostatinGrowth hormone inhibiting hormone
    Inhibits insulin and glucagon secretion
    Inhibits release of GI peptides
  30. 30What is external stimuliChange in environment to influence hormone secretion to maintain constant internal environment
    Example: Decrease in temp changes thyroid hormone release to maintain steady body temp
  31. 31Internal rhythms of hormonesCircadian rhythms - cortisol and melatonin secretion within 24 hour period
    Circannual rhythms are in breeding animals
  32. 32Negative feedback control and exampleWhen Hormone secretion increased, feedback that acts to reduce its secretion
    High blood glucose have negative feedback to inhibit glucagon
  33. 33Positive feedback control and exampleHormone secretion continually stimulated until major change happens in control system
    Positive feedback of LH and Estradiol during ovulation
    Positive feedback of Oxytocin during labour
  34. 34How hormones affect other hormones (4)Can inhibit or stimulate release, influence metabolism of other hormones, change responsiveness of tissues to other hormones via receptor number and affect response of tissue when hormone binds receptor
  35. 35Feedback independent of the nervous systemSome feedback loops don't require input from the nervous system:
    Insulin/glucagon
    Control of blood calcium by parathyroid hormone (Increase) and calcitonin (decrease)
  36. 36Calcitonin secretion and functionSecreted by parafollicular cells in the Thyroid gland. Secretion increases when blood calcium levels rise and inhibits bone resorption via inhibiting osteoclasts
  37. 37Parathyroid hormoneSecreted via parathyroid gland chief cell in response to low blood calcium. Requires vitamin D3.
    Promotes resorption of bone, calcium reabsorption in kidney and adsorption in gut
  38. 38Hierarchical controlHypothalamus - anterior pituitary - periphery gland
  39. 39Location of PituitaryAttached to the hypothalamus via Infundibulum and consists of anterior and posterior pituitary divided by the pars intermedia. Anterior is endocrine tissue and posterior is nervous tissue
  40. 40Alternative name for anterior pituitaryAdenohypophysis
  41. 41Alternative name for posterior pituitaryNeurohypophysis
  42. 42Hypothalamo-hypophysial axisNeurosecretory neurons in hypothalamus and pituitary gland.
    Hypothalamus controls pituitary gland and autonomic NS. Pituitary gland secretes hormones to control release of other hormones
  43. 43Structure and arrangement of Endocrine cellsEndocrine cels are simple cuboidal, those that secrete steroids have foamy cytoplasm due to high cholesterol content. Hormone precursors can be secreted into follicles and stored as colloid. They are arranged in clusters or columns and associated with fenestrated epithelium
  44. 44Pituitary gland circulationAnterior pituitary has no direct arterial supply. Artery supplies the rest of the pituitary gland and Hypothalamus. Blood passes through the pars distalis into capillary network then into pituitary portal veins which supply the anterior pituitary
  45. 45Function of Pituitary circulatory systemDirectly carry neurosecretions released from hypothalamus to site of action in pars distalis
  46. 46Amplification and feedback loops of signals from HypothalamusHierarchal system allows small signal from Hypothalamus to be vastly amplified before it reaches the target tissue
    System also allows for multiple long or short feedback loops
  47. 47Structures of Anterior pituitaryPars distalis, pars tuberlaris and pars intermedia
  48. 48Structures of posterior pituitarypars nervosa and infundibulum
  49. 49What is a trophic hormone?A hormone that regulates other endocrine tissues
  50. 50Structure in Pars intermediaContains Rathke's pouch and colloid filled follicles.
    Cells in pars intermedia are melanotrophs and produce MSH
  51. 51Function of Pars nervosaExtension of CNS which stores secretions of hypothalamus. Contains secretory granules of ADH or Oxytocin
  52. 52Structural cells of NeurohypophysisPituicytes - similar to astrocytes in CNS
  53. 53Pineal gland structure and functionPinealocytes and supporting glial cells form gland. Secretes melatonin
  54. 54Three regions on Adrenal cortexZona glomerulosa
    Zona Fasciculata
    Zona reticularis
  55. 55Structure and Function of Zona glomerulosaCells arranged in tufts similar to glomerulus in kidney. Cells secrete mineralocorticoids: aldosterone
  56. 56Structure and Function of Zona fasciculataCells arranged into cords and secrete glucocorticoids (cortisol) in presence of ACTH released by anterior pituitary
  57. 57Function of Zona reticularisSecretes cortisol and weak androgens
  58. 58Common features of endocrine tissuesCell arrangement in clusters or cords in association with fenestrated capillaries. Have foamy cytoplasm or store inactive forms of hormones in colloid in follicles
  59. 59Exocrine Pancreassecretes digestive enzymes into a duct into the small intestine
  60. 60Endocrine PancreasSmall clusters of cells are located within exocrine cells in the pancreas
  61. 61Name of endocrine clusters in pancreasIslets of Langerhans
  62. 62Cells of Islets of LangerhansAlpha cells - glucagon secretion
    Beta cells - Insulin secretion
  63. 63Alternate name for ADHVasopressin
  64. 64Neurohumeral reflexSensor to brain neural pathway, integration site and response to sensor via hormone secretion
  65. 65Control of Vasopressin releaseIncreased solute conc. or decreased vol. in blood signalled to hypothalamus via vagus nerve
    Neurons in Hypothalamus activated and vasopressin secreted
  66. 66Control of Oxytocin releaseSuckling of nipple stimulates hypothalamus to secrete oxytocin which contracts myoepithelial cells around milk ducts which expels the milk
    Stretch receptors in cervix during birth also stimulate oxytocin release
  67. 67Life of a hormoneSynthesis within endocrine cell
    storage and or release
    Carried throughout body via blood
    Some hormone binds receptor, some lost in urine or metabolism
    Once bound: Initiates response and is degraded
  68. 68Peptide hormone synthesisDNA sequence transcribed into RNA and translated into AA sequence containing pre and pro region. Pre-region is signal molecule
    Prohormones can become more than one hormone due to post translational processing
  69. 69Gene coding glucagonIn pancreas: pre-proglucagon cleaved to form glucagon
    In intestine: Same gene expressed but cleavage does not yield glucagon
  70. 70How is cholesterol in the body? (2)Dietary and synthesised from acetate via enzyme.
  71. 71Synthesis of Steroid hormonesGenes that code for particular enzymes that create the hormones are different in each organ
  72. 72How is cholesterol circulated in the blood and taken up into cells and stored?Cholesterol circulates attached to LDL and binds LDL receptors on cells and stored as lipid droplets or cholesterol esters
  73. 73What is cholesterol converted to and how does this become steroid hormones?Cholesterol converted to Pregnenolone via mitachondria and Pregnenolone becomes hormones via smooth ER
  74. 74Four main types of steroid hormonesProgestins
    Corticosteroids
    Androgens
    Estrogens
  75. 75Progestin synthesisMain progestin is progesterone, synthesised directly from Pregnenolone
  76. 76Corticosteroid synthesisMineralocorticoids - Aldosterone
    Glucocorticoid - Cortisol
    Pathway has 1 intermediate step (Cortisol)
    or 2 (Aldosterone)
  77. 77Androgen synthesisAndrogens are synthesised from Pregnenolone or progesterone via androstenedione to testosterone
  78. 78Estrogen synthesisSynthesised from androgens
    Androstenedione - esterone - estradiol
    Testosterone - estradiol
  79. 79Synthesis of thyroid hormones (3)Active transport of Iodine from blood into follicle cells - symport with Na+
    Iodination of tyrosine in thyroglobulin
    Coupling of Iodo-tyrosines to form T3 and T4
  80. 80Storage of thyroid hormonesT3 and T4 stored as thyroglobulin in colloid and transported into follicle via Pinocytosis
  81. 81Transport of hormones in bloodPeptide hormones can travel through blood without being attached to carrier proteins
    Steroid and thyroid hormones bind plasma proteins
  82. 82Excretion of thyroid hormonesWhen release of hormones stimulated, endocytotic vesicles containing thyroglobulin fuse with lysosymes and proteolysis of thyroglobulin forms T3 and T4 which are released into cytoplasm then blood
  83. 83Agonist and antagonistsAgonist - Mimic action of natural hormone
    Antagonist - block action
  84. 84Receptor regulationNumber of hormone receptors regulated by presence of hormone or other hormones. Example: Estrogens increase number of progesterone receptors, but progesterone decreases amount of progesterone receptors
  85. 85Effect of receptor down regulationInsensitivity to hormone during continued high secretion - type 2 diabetes
  86. 86Permissive effect of hormone exampleEstogen priming uterus up-regulating progesterone receptors before progesterone can have an effect
  87. 87Synergistic hormonesWork together to form function
  88. 88Antagonistic hormonesexample: Glucagon and insulin or parathyroid hormone and calcitonin: opposite effects
  89. 89Where are the receptors peptide hormones bind?On cell membranes, generate second messengers
    GPCRs
    cAMP - protein kinase
    Ca2+ PIP2 - IP3 and DAG
  90. 90Three domains of cell receptors that bind hormonesExtracellular, transcellular and cytoplasmic
  91. 91Where are the receptors that bind steroid hormones?mainly Intracellular receptors
    Hormones pass through cell membrane and bind receptors in cytoplasm or nucleus and activate transcription. Some can still bind cell membrane - rapid response
  92. 92Where are the receptors that bind thyroid hormones? What happens when T4 in cytoplasmT3 and T4 enter cells, T4 becomes T3 in cytoplasm. T3 binds receptor in nucleus and initiates transcription T3 receptors always bound to DNA
  93. 93Importance of glucose and target concentrationEssential for brain and important for the conversions of carbohydrates, lipids and proteins in liver
    100mg/dl
  94. 94intermediary metabolismprocessing of compounds from digestion for immediate use or storage and the processes when stored compounds are used
  95. 95Metabolism of carbohydratesCarbs digested into glucose, sucrose and fructose during digestion. Sucrose and fructose converted to glucose in liver. Aount of glucose required by cells is oxidised and additional is stored as glycogen-fat or excreted via urine.
    Glycogen stored in liver and skeletal muscle
  96. 96GluconeogenesisAnabolic process
    Glucose formed in liver from fat and proteins
  97. 97GlycogenolysisGlycogen broken down in liver to form glucose, in liver only
    In skeletal muscle - anaerobic and forms lactate
  98. 98Metabolism of fatsFat - 3 fatty acids and glycerol
    Triglycerides absorbed in gut and transported to adipose tissue via liver.
    Used as energy when carb stores low, harder to oxidise
  99. 99Anabolism of fatsLipogenesis occurs in liver and adipose tissue after digestion.
    Glucose forms glycerol and fatty acids which then form lipids
    Excess protein also forms fat
  100. 100Catabolism of fatsFat broken down into glycerol and fatty acids. In the liver glycerol converted to glucose. High fat meal or starvaion induces fatty acids to become ketones which supply energy to body
  101. 101Protein metabolismProteins broken down to amino acids which are carried to cells via blood where they used to make new proteins.
    Proteins catabolised in muscles and amino acids used in the liver to form glucose or fat and oxidised to form energy
  102. 102Pancreatic delta cellsSecretes somatostatin which inhibits glycogen and insulin secretion
  103. 103Pancreatic F cellsSecrete pancreatic polypeptide, inhibits pancreatic exocrine secretion
  104. 104Where are insulin and glucagon secreted and why?Into hepatic portal vein to reach liver which processes nutrients and maintains blood glucose
  105. 105Functions of InsulinIncrease uptake of glucose into cells
    promote utilisation of glucose
    stimulate glycogen and lipid formation
    Inhibit enzymes that promote breakdown of glycogen and lipids
  106. 106Functions of GlucagonStimulates glycogenolysis, lipolysis and glucose release from liver
  107. 107Affects of other hormones on blood glucoseAdrenaline - Glycogenolysis in liver and muscle
    Growth hormone and cortisol - Glycogenolysis and lipolysis
    Thyroid hormone - stimulates carb and lipid metabolism
  108. 108Insulin and glucagon concentrations during feedingHigh insulin and low glucagon as glucose concentration increases during feeding
  109. 109Insulin and glucagon concentrations during fastingHigh glucagon and low insulin to maintain steady glucose level.
    Growth hormone also increased.
    Glucose conserved and cells use fatty acids instead
  110. 110Affects of Diabetes mellitus due to low glucosedilute urine, thirst, high blood fat, atherosclerosis, ketosis and protein depletion in tissues
  111. 111Type 1 diabetesInsulin dependent
    Lack of insulin secreted from pancreas
  112. 112Type 2 diabetesNon insulin dependent
    not a lack of insulin but lack of response to insulin
  113. 113Somatotropin secretion and regulationGrowth hormone produced by somatotrophs in pituitary gland. Release is controlled by Somatocrinin and Somatostatin released from Hypothalamus and acts on all cells not just a target cell
  114. 114Major hormones controlling growth (3)Thyroxine (T4), growth hormone and androgens (Testosterone and Androstenedione)
  115. 115Function of growth hormoneAnabolic effect by increasing uptake of AAs into cells and stimulates protein synthesis.
  116. 116Function of thyroxine on growthHas permissive effect on the action of growth hormone in cells
  117. 117Function of androgens on growthIncrease protein synthesis and stimulate rapid growth of epiphyseal plates in long bones. After puberty the plates fuse and don't grow anymore
  118. 118Long term actions of Growth hormoneIndirect effects.
    Determine appropriate composition of body
    Determine size while growing and maintain normal function during adulthood. Stimulate IGF release from liver which cause bone and tissue growth
  119. 119Short term actions of growth hormoneDirect effects
    During fasting, blood glucose drops and growth hormone secretion stimulated and changes energy source from carbs to fats, breaking down fats to ketones to increase blood glucose
  120. 120How is growth hormone secretion controlled?GHRH and GHIH released from hypothalamus either enhancing or inhibiting growth hormone release from anterior pituitary. IGF have negative feedback on pituitary gland and hypothalamus
  121. 121Factors increasing GH release (5)Sleep, stress, low blood sugar, fasting and exercise
  122. 122Factors decreasing GH release (3)High blood glucose, high fatty acid levels in blood,
    obesity
  123. 123Affects of Dwarfism on GHLack during childhood, low IGF production but normal GH or lack of GF receptor
  124. 124GigantismHyper secretion of GH usually due to pituitary tumor
  125. 125Function of thyroid hormonesRegulate metabolism, increase transcription and protein synthesis in cells to increase activity - increased oxygen, heat production and metabolism, increased no. mitochondria
    Stimulate carb and lipid metabolism and fatty acid oxidation
  126. 126Influence of thyroid hormones on growthRequired for foetal and infant brain development and for normal brain function. Increased: Excitability and anxiety, decreased: mental sluggishness
  127. 127Control of thyroid hormone secretionThyrotropin releasing hormone (TRH) in hypothalamus stimulates Thyroid stimulating hormone (TSH) from anterior pituitary gland.
  128. 128Regulation of catecholamine secretionStress, excitement, pain activates hypothalamus which controls sympathetic nerves which activate secretion of adrenaline and noradrenaline in adrenal medulla rapidly, causing vasoconstriction in viscera, dilation in skeletal muscle, increased heart rate and glycogenolysis
  129. 129Regulation of Cortisol secretionHypothalamus released CRH simulating anterior pituitary to release ACTH. Awakening in the morning causes increase in CHR hence increased Cortisol
    Cortisol also helps maintain blood glucose
  130. 130Cushing's diseaseHypersecretion of cortisol. Pituitary tumor causes increased ACTH leading to mobilisation of fat from lower body to head and chest. Protein catabolism causes muscle wastage. Immune system suppressed
  131. 131Addison's diseaseFailure of adrenal cortex to produce steroids. Lack of aldosterone leads to decreased sodium reabsorption and loss in urine. ECF and heart output reduced, uncontrolled blood glucose, reduced protein and fat metabolism. Can be fatal

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Physiology exam study Flashcards on Introduction to Endocrine system, created by Kelly C on 14/05/2019.
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