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Flashcards

Thyroid Gland

Riya X Other Undergraduate English 79 cards

Thyroid Gland

Cards in this deck (79)

  1. 1Label this diagram of the thyroid glandLabel this diagram of the thyroid glandLabel this diagram of the thyroid gland
  2. 2What are the parathyroid glands involved in?Control of plasma calcium
  3. 3What does the thyroid gland adhere to?Trachea
  4. 4Describe the appearance of the thyroid gland2 large, asymmetrical flat lobes connected by an isthmus
  5. 5Roughly how much does the thyroid gland weigh?10-20 g
  6. 6Compare the blood flow of the thyroid gland to that of the kidneyThe thyroid gland has a rich blood supply - blood flow twice that of the kidney
  7. 7What regulates the thyroid gland?Hypothalamus and pituitary gland
  8. 8When is the thyroid gland fully developed? What does this mean?Week 12 of gestation
    This means thyroid hormones are crucial for subsequent foetal growth and development
  9. 9Which blood vessels supply the thyroid gland?Superior and inferior thyroid arteries
    Branches of the external carotid artery
  10. 10What is the functional unit of the thyroid gland called?Follicle
  11. 11How many follicles (roughly) are in each gland?1000's
  12. 12What does each follicle consist of?A layer of follicular cells surrounding a colloid-filled cavity
  13. 13What type of cells are follicular cells?Simple cuboidal epithelial
  14. 14What do follicular cells secrete?Thyroid hormone
  15. 15What type of molecule is thyroid colloid?Glycoprotein
  16. 16What do C cells secrete?Calcitonin
  17. 17Label the numbered arrows on this histological diagram of the thyroid gland1. Follicular cells
    2. Colloid
    3. Capillary    Label the numbered arrows on this histological diagram of the thyroid gland
  18. 18Name the two thyroid hormones and give their abbreviated formsTriiodothyronine (T3)
    Thyroxine (T4)
  19. 19How much thyroxine (T4) does the thyroid secrete per day?80 ug
  20. 20How much triiodothyronine (T3) does the thyroid secrete per day?5 ug
  21. 21Which thyroid hormone has a much greater biological activity (about 10x greater)?T3
  22. 22Why are they called T3 and T4?T3 and T4 contain three and four atoms of iodide per molecule, respectively
  23. 23How is reverse T3 different to T3 and T4?It is biologically inactive
  24. 24Roughly what percentage of T3 and T4 is present in 'free form'?Less than 0.5%
  25. 25Name two molecules that T3 and T4 are bound to in plasmaThyroxine-binding globulin
    Albumin
  26. 26What hormone class are the thyroid hormones?Amino-acid derived
  27. 27Which amino acid are thyroid hormones derived from?Tyrosine (thyroid hormones are essentially iodinated tyrosine)
  28. 28Name the two principle raw materials required for the synthesis of thyroid hormonesTyrosines
    Iodine
  29. 29What is tyrosine provided by? Where is this found?Thyroglobulin - secreted by follicular cells into lumen of follicle as colloid
  30. 30How does iodine enter follicular cells?It is pumped in against the concentration gradient
  31. 31Explain how T3 and T4 are synthesisedExplain how T3 and T4 are synthesised
  32. 32What is the main advantage of the system by which the thyroid hormones are synthesised?The thyroid gland is capable of storing many weeks worth of thyroid hormone (coupled to thyroglobulin) within the colloid. This means that if no iodine is available for this period, thyroid hormones secretion will be maintained.
  33. 33Give some examples of iodine rich food sourcesProcessed foods than contain iodized salt
    Breads that contain iodate dough conditioners
    Sea vegetables
    Yogurt, cow's milk, eggs, strawberries
  34. 34Give some examples of where thyroid receptors can be found in the bodyLiver
    Brain
    Kidney
    Hypothalamus
    Pituitary
  35. 35What percentage of thyroid hormone released by the gland is T4?90%
  36. 36What is name of the process which involves the enzymatic conversion of T4 into T3 in peripheral tissues (liver and kidneys)?Peripheral conversion
  37. 37Define 'peripheral conversion'Enzymatic conversion of T4 into T3 in peripheral tissues (liver and kidneys)
  38. 38Where does peripheral conversion take place?In peripheral tissues - liver and kidneys
  39. 39What is the name of the medication usually taken to treat hypothyroidism?Levothyroxine (L-thyroxine)
  40. 40What is levothyroxine chemically identical to?Thyroxine (T4)
  41. 41What is the likely reason for hypothyroid patients being given T4 and not T3 supplements?T3 might not be stable in tablet form and may not be easy to store
    The body will convert the T4 into T3 so it is not vital to have T3 supplements directly
  42. 42What are the four principle actions of thyroid hormones?Metabolism
    Heat production (calorigenic effect)
    Growth and development
    Cardiovascular function
  43. 43What do thyroid hormones do to metabolism?Increase mobilisation and utilisation of glucose, fat, and protein
  44. 44Why is the calorigenic effect of thyroid hormones important?It is important in temperature regulation and adaptation to cold envrionments
  45. 45What do thyroid hormones work in synergy with, in regards to growth and development?Growth hormone
  46. 46What can thyroid hormone deficiencies lead to, with regards to growth and development?Mental impairment
    Short stature
  47. 47What is the cardiovascular function of thyroid hormones?Increased cardiac output, heart rate and contractility
  48. 48What 2 main thyroid functions does TSH (thyroid stimulating hormone) stimulate?Promoting the release of thyroid hormones into the bloodstream
    Increasing the activity of the iodide pump and iodination of tyrosine to increase the production of thyroid hormones
  49. 49Give an overview of hypothyroidismUnderactive thyroid
    Metabolic rate decreases
    Weight gain
  50. 50Give an overview of hyperthyroidismOveractive thyroid
    Metabolic rate increases
    Weight loss
  51. 51Give some examples of symptoms of hypothyroidism- Dry, cold skin
    - Sensitivity to cold
    - Weight gain despite loss of appetite
    - Impaired memory
    - Mental dullness
    - Lethargy
    - Myxoedema
  52. 52What is myxoedema?Cutaneous and dermal oedema secondary to increased deposition of connective tissue components (glycosaminoglycans), particularly beneath the eyeWhat is myxoedema?
  53. 53If you were to examine someone with hypothyroidism, what would some of the clinical symptoms be?Reduced metabolic rate
    Slow pulse
    Reduced cardiac output
    Low plasma levels of T3 and T4
  54. 54What would the treatment for hypothyroidism be? How would the dose be determined?Thyroxine
    Dose determined by TSH monitoring
  55. 55Why would TSH levels increase if you have low levels of T3 and T4?The pituitary will continue to secrete it in an attempt to stimulate the thyroid gland because it does not know that iodide is deficient and cannot enable the production of T3 and T4
  56. 56What would happen to TSH levels in hypothyroid individuals once they have started being supplemented with thyroxine?TSH levels will decrease, showing that the supplements are effective
  57. 57What are some of the causes of hypothyroidism?1. Iodine deficiency (endemic goitre)
    2. Autoimmune disease (Hashimoto's thyroiditis)
    3. Congenital
    4. Post radiation/surgery
    5. Medications
    6. Stress
  58. 58What do individuals with iodine deficiency (endemic goitre) present physically?A very enlarged thyroid gland
  59. 59Describe iodine deficiency (endemic goitre)Insufficient dietary iodine so insufficient amounts of T3 and T4, which leads to reduction in negative feedback of TSH by the pituitary
    Abnormally high TSH
    Abnormal growth of the thyroid due to the trophic effects of TSH
  60. 60What treatment would be given to individuals with iodine deficiency (endemic goitre)?Iodine supplements
    Thyroxine (T4)
  61. 61What condition is the most common cause of hypothyroidism?Hashimoto's disease
  62. 62Describe Hashimoto's disease and how it leads to hypothyroidismAutoimmune disease
    - Antibodies against TSH receptor in thyroid gland
    - TSH cannot bind to its receptor
    - Prevents stimulation of T3 and T4 release
    - Antibodies also against thyroid peroxidase and thyroglobulin
    Eventually leads to thyroid gland destruction
  63. 63What is congenital hypothyroidism also known as? How many births does it affect?Cretinism - 1 in 4000 birth
  64. 64What are some of the symptoms of congenital hypothyroidism/cretinism?Mental retardation (if treatment later than 3 months)
    Short, disproportionate body
    Thick tongue and neck
  65. 65What is the cause of congenital hypothyroidism?Lack of gland or incorrect hormone biosynthesis
  66. 66Which test done on babies is used to check levels of thyroid hormones, amongst others?Heel prick test (Guthrie test)
  67. 67What levels of TH, TSH, and TRH would you expect in individuals with hypothyroidism? (Higher or lower than normal?)TH - lower
    TSH - higher
    TRH - higher
  68. 68What are the symptoms of hyperthyroidism?- Loss of weight
    - Excessive sweating/intolerance to heat
    - Palpitations and an irregular heartbeat
    - Anxiety and nervousness
    - Exopthalamus (abnormal protrusion of eye)
  69. 69If you were to examine an individual with hyperthyroidism, what clinical symptoms would you expect to see?Raised metabolic rate and oxygen consumption
    Increased heart rate
    Hypertension
  70. 70What are some of the treatment options for individuals with hyperthyroidism?Surgical removal of all or part of the thyroid
    Ingestion of radioactive iodine that selectively destroys the most active thyroid cells
    Various drugs (thionamides - methimazole, carbimazole, propylthiouracil) that interfere with the gland's ability to make T3 and T4
  71. 71What are the disadvantages of surgical removal of part or all of the thyroid to treat hyperthyroidism?Permanent hypothyroidism
    Risk of hypoparathyroidism
    Recurrent laryngeal nerve damage
  72. 72What are the disadvantages of treating hyperthyroidism with radioiodine?Permanent hypothyroidism
    Oncogenic effects of radiation
  73. 73What are the disadvantages of using thionamides to treat hyperthyroidism?- Rash
    - Arthragias (joint stiffness)
    - Gastrointestinal discomfort
    - Agranulocytosis
    - Vasculitis
    - Hepatitis
  74. 74Name the three thionamides that could be used to treat hyperthyroidismMethimazole
    Carbimazole
    Propylthiouracil
  75. 75Give an example of one of the causes of hyperthyroidismAutoimmune disease - Grave's disease
  76. 76Describe Grave's diseaseAutoimmune production of thyroid-stimulating antibody (which mimics TSH)
    This binds to and activates the TSH receptor inducing T3/T4 release
    Characterised by diffuse goitre, exopthalamus and lid retraction
  77. 77What levels of TH, TSH and TRH would you expect in individuals with hyperthyroidism? (Higher or lower than normal?)TH - higher
    TSH - lower
    TRH - lower
  78. 78What are some of the common oral findings in hypothyroid individuals?Macroglossia (abnormal enlargement of tongue)
    Dysgeusia (abnormal taste)
    Delayed eruption
    Poor periodontal health
    Delayed wound healing
  79. 79What are some of the common oral findings in hyperthyroid individuals?Increased susceptibility to caries
    Periodontal disease
    Maxilary and mandibular osteoporosis
    Accelerated eruption
    Burning mouth syndrome

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Undergraduate Other Flashcards on Thyroid Gland, created by Riya X on 19/07/2021.
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Riya X
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