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Flashcards

Hormones

Olivia Hearn Structure and Function Undergraduate Inglês 81 flashcards

Flashcards do conjunto (81)

  1. 1Endocrine glandSecretes hormones into the bloodstream
  2. 2HormoneChemical messenger that regulates growth, metabolism, reproduction and homeostasis.
    Slower reaction time than the nervous system.
  3. 3AutocrineHormonal effect is exerted on its own cells
  4. 4ParacrineHormonal effect is exerted on neighbouring cells/far away organs.
  5. 5What are whole body hormonal actions?1. Ionic and Fluid balance
    2. Energy balance
    3. Coping with environment stress
    4. Growth
    5. Reproduction
  6. 6What are molecular level hormonal actions?1. Gene transcription regulation
    2. Protein synthesis and degradation
    3. Enzyme activity
    4. Protein conformation
  7. 7What are cellular level hormonal actions?1. Regulation of cell division
    2. Differentiation
    3. Apoptosis
    4. Motility
    5. Secretion
    6. Nutrient Uptake
  8. 8What are the features of Steroid functions?1. Receptor located in the cytosol or nucleus
    2. Binds to DNA/modifies transcription
    3. Slow effect
    4. Permanent effects
    5. Made of cholesterol
    6. Examples are testosterone and oestrogen
  9. 9What are the features of Peptide Hormones?1. Made of amino acids
    2. Receptor located on cell surface
    3. Acts as second messengers
    4. Rapid response
    5. Temporary effect
    6. Examples are ADH and growth hormone
  10. 10Negative feedbackThe counteraction of an effect by its own influence on the process giving rise to it.
  11. 11Positive feedbackThe amplification of an effect by its own influence on the process which gives rise to it.
  12. 12OxytocinControls lactation and uterine contraction at onset of labour
  13. 13ADHActs on the collecting ducts in the kidneys to reabsorb water
  14. 14Anterior pituitaryThe regulator of the endocrine system.
    Secretes mostly tropic hormones.
    Located on the same side as the optic chiasm.
    Releases FSH and LH.
  15. 15Posterior pituitaryReleases ADH and oxytocin.
  16. 16AdenohypophysisAnterior lobe of brain
  17. 17NeurohypophysisPosterior lobe of the brain
  18. 18Neuroendocrine reflex1. Oxytocin binds to receptors
    2. Increase in Calcium ions in myoepithelial cells of mammary glands
    3. Milk ejection due to activation of contractile machinery
    Suckling
    Hypothalamus
    Posterior pituitary
    Oxytocin release
    Milk ejection
  19. 19What releasing hormones are stimulatory?CRH
    GRH
    TRH
    GHRH
  20. 20What releasing hormones are inhibitory?Dopamine
    Somatostatin
  21. 21Growth hormoneSynthesised and stored in somatotophs.
    Principle targets are bone and skeletal muscle.
  22. 22What is the effect of growth hormone in muscle?Increase amino acid uptake
    Decrease glucose uptake
    Decrease protein breakdown
    Increase muscle mass
  23. 23What is the effect of growth hormone in adipose?Increase lipolysis
    Decrease glucose uptake
    Decrease fat deposits
  24. 24What is the effect of growth hormone in liver?Increase gluconeogenesis
    Increase protein synthesis
    Increase IGF production
  25. 25IGF1Insulin-like growth factor which is a primary mediator on the effects of growth hormone.
    Causes skeletal growth by forming cartilage and depositing bone.
    Causes soft tissue growth by protein synthesis and cell proliferation.
  26. 26When does the bone response cease to GH?Growth plates fuse
  27. 27SomatopauseA gradual and progressive decrease in growth hormone secretion that occurs normally with increasing age during adult life and is associated with an increase in adipose tissue and LDL levels and a decrease in lean body mass and bone mineral density.
  28. 28What is the mechanism for how GH is secreted?1. GHRH is released from the hypothalamus
    2. GH is released from the anterior pituitary
    3. IGF is released from the liver
    4. Downstream effects in many tissues, mainly bone and muscle
  29. 29What disorder can arise from excess GH?1) Gigantism - Abnormal linear growth due to excessive IGF action in children when the epiphyseal plates are still open.
    2) Acromegaly - Increased GH later in life after the fusion of epiphyses. Symptoms are enlarged hands and feet, protruding jaw and separation of teeth, diabetes because GH opposes insulin.
  30. 30What disorder can arise from GH insufficiency?Pituitary dwarfism - Slow growth rate below the third centile, normal body proportions, excess subcutaneous fat, poor muscle development.
  31. 31Thyroid Gland1) Two large asymmetrical flat lobes connected by the isthmus
    2) Fully developed by week 12 of gestation
    3) Responds to TSH by 22 weeks
    4) Functional unit is the follicle
    5) Each follicle consists of follicular cells made of simple cuboidal epithelium
    6) Epithelium surrounds colloid
    7) Colloid is a fluid-filled cavity made of glycoprotein
    8) Follicular cells secrete thyroid hormone
    9) C cells secrete calcitonin
  32. 32Which thyroid hormone has greater biological activity?T3
  33. 33Why are the thyroid hormones named T3 and T4?They have three and four atoms of iodide per molecule respectively
  34. 34Which thyroid hormone has a shorter half life?T3 (1-3 days)
  35. 35What are thyroid hormones bound to?Thyroxine binding globulin (TBG), albumin or TTR
  36. 36What is rT3?Reverse T3 is biologically inactive and is derived from tyrosine and has a half life of 5 hours
  37. 37How is thyroid hormone synthesised?1. Thyroglobulin synthesised and enters follicle lumen
    2. Iodide actively transported into lumen and trapped
    3. Iodide oxidised to iodine
    4. Iodine attached to tyrosine to form DIT and MIT
    5. Iodinated tyrosines linked to form T3 and T4
    6. Thyroglobulin colloid is endocytosed and combines with a lysosome
    7. Lysosomal enzymes cleave T3 and T4 from thyroglobulin and hormones diffuse into the bloodstream
  38. 38What is the advantage of thyroid hormone synthesis?The thyroid gland can store weeks worth of TH coupled to thyroglobulin so, if no iodine is available, then TH secretion will be maintained.
  39. 39What are the sources of iodine?Seaweed
    Yoghurt
    Cow's milk
    Eggs
    Strawberries
  40. 40TRB1A thyroid hormone receptor in the liver, brain and kidneys
  41. 41TRB2A TH receptor in the hypothalamus and pituitary
  42. 42THa1A TH receptor throughout the body
  43. 43What hormone is released from the thyroid?90% released is T4 but it is converted to T3 due to its higher biological activity
  44. 44What is L-thyroxine?A synthetic thyroid hormone chemically identical to T4
  45. 45How does thyroid hormone affect heat production?Calorigenic effect
    Temperature regulation
    Adaptation to cold environments
  46. 46How does thyroid hormone affect the cardiovascular system?Increases cardiac output, heart rate, contractability and ventilation rate
  47. 47What is the effect of TSH release from the hypothalamus?Promotes release of TH from the anterior pituitary.
    Increases activity of iodide pump
    Increases production of thyroid hormones
  48. 48TRH TSH T4 and T3 Metabolic production, heat production, enhancement of growth, CNS development, enhancement of sympathetic activityTH suppresses production of TSH
  49. 49What effects does an iodine deficiency cause?Endemic goitre
    Insufficient dietary iodine
    Insufficient T3 and T4
    High TSH
    Abnormal growth of thyroid
  50. 50What is Hashimoto's disease?Hypothyroidism
    Autoimmune
    Antibodies against TSH receptor prevents TSH binding to receptor
    No T3 or T4 released
    Antibodies against thyroid peroxidase and thyroglobulin causes thyroid gland destruction.
  51. 51What is Congenital Hypothyroidism?Cretinism
    1 in 4000
    Mental retardation
    Short disproportionate body
    Thick tongue and neck
    Lack of gland
  52. 52Adrenal Glands1) Enclosed in a fibrous capsule
    2) Each adrenal gland is equivalent to two endocrine glands
    3) Inner part is the medulla
    4) Outer part is the cortex
    5) Cortex secretes steroid hormones
    6) Layers of the gland include:
    Capsule
    Zona glomerulosa
    Zona fasciculata
    Zona reticularis
    Medulla
  53. 53Zona glomerulosaRegulated by potassium ions
    Secretes mineralocorticoids e.g aldosterone
  54. 54Zona fasciculataRegulated by ACTH
    Secretes glucocorticoids e.g cortisol
  55. 55Zona reticularisRegulated by ACTH
    Secretes adrenal androgens (gonadocorticoids) e.g DHEA
  56. 56Medulla1) Consists of chromaffin cells that secrete adrenaline and noradrenaline
    2) Not under hormonal control so is not a true endocrine organ
    3) Splanchnic nerves are the preganglionic neurons
  57. 57What receptors does adrenaline act on?Beta receptor e.g B1, B2 and B3
  58. 58What are short term stress responses triggered by?Catecholamines
  59. 59What are long term stress responses caused by?Mineralocorticoids and glucocorticoids
  60. 60Describe Steroid BiosynthesisCholesterol
    Pregnenolone
    Progestagens
    Glucocorticoids, mineralocorticoids and androgens
  61. 61Which enzyme does the zona glomerulosa lack?17a-hydroxylase
  62. 62What enzyme does the zona fasciculata and zona reticularis lack?18-hydroxylase
  63. 63What is 21-hydroxylase deficiency?Deoxycorticosterone cannot be made
    No aldosterone is produced
    No cortisol is produced
  64. 64What are the effects of testosterone?Contribute to secondary characteristics such as aggression.
  65. 65What are the effects of female androgens?Growth of pubic hair and contribution to sex drive
  66. 66What is the role of aldosterone?Controls ECF volume and conservation of body sodium.
    Stimulates reabsorption of sodium in renal DCT in exchange for potassium
  67. 67What are the effects or cortisol?Increased plasma and FFA concentration
    Increased skeletal muscle protein catabolism via gluconeogenesis
    Increased lipolysis
    Stimulates appetite
    Anti-inflammatory
    Immunosuppressive
    Counteracts the effects of stress
  68. 68What is hypoaldosteronism?Low serum sodium concentration
    High serum potassium ion concentration
    Dehydration
    Postural hypotension
    Weight loss
    High plasma renin concentration
    Excess ACTH produces melanin
  69. 69What are the functions of calcium?Structural component of bones and teeth
    Maintains normal excitability of nerve and muscle cells
    Neurotransmitter release
    Muscle contraction
  70. 70Where is calcium regulated?Intestines - absorption
    Kidneys - excretion of urine
    Bones - temporary storage
  71. 71Parathyroid hormoneA peptide hormones stored in chief cells
    Secreted in response to low blood calcium
    Stimulates osteoblast receptor which indirectly stimulates osteoclasts
  72. 72What is the function of 1a-hydroxylase?Activates vitamin D to reabsorb more calcium from the urine in the kidneys
  73. 73What is the effect of PTH?Stimulates bone absorption
    No direct effect on the intestine
    Increases expression of 1a-hydroxylase
  74. 74Which type of vitamin D is found in food supplements?D2
  75. 75Which type of vitamin D is synthesised in the skin in the presence of sunlight?D3
  76. 76Why are D2 and D3 converted to calcitriol?They are inactive.
    Calcitriol increases production of calcium transport proteins and increases calcium uptake in the gut.
    Increases rate of bone resorption and increases secretion of osteoclast activating factors.
    There is a minor effect in decreasing urinary loss of calcium in the kidneys.
    Overall, increases blood calcium levels.
  77. 77How does the body respond to low plasma calcium levels?1. PTH produced
    2. Osteoclast activation
    3. Bone resorption
    4. Less calcium excreted into urine from kidneys
    5. Expression of 1a-hydroxylase increased
    6. Activation of calcium transport proteins
    7. More calcium in circulation
  78. 78CalcitoninSecreted by C cells (parafollicular cells) of the thyroid gland.
    Lowers plasma calcium
    Decreases osteoclast activity
    Decreases bone resorption
    Increases excretion of calcium and phosphate via the kidneys
    When blood calcium gets too high, PTH is suppressed so we don't often use calcitonin
    Used in pregnant or lactating women who require more calcium deposition
  79. 79What is hyperparathyroidism?Causes hypercalcaemia
    Decrease in PTH secretions
    Calcitriol inhibits PTH synthesis
    Leads to kidney stones
  80. 80What is hypocalcaemia caused by?Vitamin D deficiency
    The growth plates do not form
    Weakened bones
    Increased excitability of nervous tissue
    Reduction in intestinal calcium absorption
  81. 81Is hypocalcaemia in vitamin D deficient patients likely to become severe?No due to compensatory rise in PTH. The body sacrifices bone stores which presents weaker bones but is not life threatening.

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Undergraduate Structure and Function FlashCards sobre Hormones, criado por Olivia Hearn em 16-05-2019.
Criado por
Olivia Hearn · mai 2019
Atualizado
17 mai 2019
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