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BRS > week 3-L2-thyroid gland > Flashcards

week 3-L2-thyroid gland Flashcards

1
Q

thyroid gland labels top to bottom

A

thyroid cartilage, thyroid gland, isthmus and pyramid

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2
Q

thyroid gland interior structures

A

follicles, follicular cells and colloid + parafollicular cells

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3
Q

dangers of thyroidectomy

A

presence of parathyroid glands and left recurrent laryngeal nerves that runs close to thyroid

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4
Q

recurrent laryngeal nerve function

A

supply the vocal cords

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5
Q

parathyroid glands

A

embedded in thyroid and control calcium levels

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6
Q

thyroid gland embryology

A 
originates base of tongue
thyroglossal duct develop
divides to 2 lobes
duct disappear leaving foramen caecum
final position by week 7
thyroid glands develop
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7
Q

problems with thyroid glands development

A

may not develop at all or may not completely descend

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8
Q

thyroid gland mechanism to TSH

A

binding of TSH to TSH-R
I- and Na+ transportation into follicular cell and colloid
oxidation aka iodination of I- to I
binding to TSH-R cause enzyme activation TPO and TG
TPO catalyse peroxide breakdown
peroxides cause TG and binding of tyrosine residue forming MIT and DIT
coupling reaction to form T3 and T4
secretion into the blood

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9
Q

T3 formation

A

coupling between DIT and MIT

presence of 3,5,3 iodine

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10
Q

T4 formation

A

coupling between 2 DIT molecule

presence of 3,5,3,5 iodine

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11
Q

T4 aka

A

thyroxine

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12
Q

which is the main hormone product in the thyroid gland

A

thyroxine or T4

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13
Q

why is T4 the main hormone product?

A

can be deiodinated to T3, its bioactive form

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14
Q

deiodination of T4/ thyroxine

A

produce 2 different products- T3 active and reverse T3
NB: reverse T3 is not active, 2 iodine on the 2nd side chain
enzyme- deiodinase

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15
Q

circulating T3

A

80% from T4 deiodination and 20% from direct thyroidal secretion

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16
Q

plasma protein bound to T3 and T4

A

thyroid-binding globulin
albumin
prealbumin

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17
Q

are plasma bound T3 and T4 active

A

no oney unbound components are active

18
Q

where is TG found

A

only in the thyroid

19
Q

where is TGB found

A

in the circulation

20
Q

% T3 and T4 unbound and what does it show?

A

0.05 T4 and 0.5 T3, most thyroid hormone are inactive

21
Q

T3 and T4 mechasnim of action

A

T4 conversion to T3 and T3 alter gene expression

22
Q

cretinism

A

untreated congenital hypothyroidism due to foetal growth and development impaired as thyroxine not produced by own body

23
Q

how is TSH measure in newborn

A

heel prick test, if high=> not producing own thyroid hormone

24
Q

thyroid hormone actions

A

increase basal metabolic rate
protein, fat and carbohydrate metabolism
potentiate action of catecholamines
effects on the GI, CNS and reproductive system

25
Q

T4 half life

A

7-9 days

26
Q

T3 half life

A

2 days

27
Q

are thyroid disorders most common in mean or women or same?

A

women with 4:1 ration due to autoimmune system and pregnancy

28
Q

overreactive thyroid or under reactive thyroid more common?

A

same

29
Q

primary hypothyrodism

A

autoimmune damage to the thyroid
thyroxine levels drops and TSH levels increase
suppose the thyroid is chopped off- decr in T3 and T4- -ve feedback to hypothalamus to produce more TSH- side effects due to other hormone produced along with TSH

30
Q

common forms of autoimmune thyroid disease

A

Hashimoto thyroiditis and Graves’s disease

31
Q

what does presence of 1 autoimmune disease imply

A

may increase the risks of other autoimmune diseases

32
Q

signs and symptoms of hypothyrosidm

A

cold intolerance, depression and tiredness, weight gain with reduced appetite, constipation, Bradycardia, deepening of voice, eventual myxoedema coma

33
Q

drugs for primary hyperthyrodism

A

levothyroxine

34
Q

mechanism of action of levothyroxine

A

production of T4 as alternative to be deiodinated

35
Q

dosing of levothyroxine

A

common dose is 100mg administered orally but adjusted according to normal range of TSH

36
Q

potential complication of to levothyroxine

A

minor-weight loss or headache

major-heart attack and rapid heart rate

37
Q

why no use Liothyroxine

A

T3 supplement are not needed due to deiodinase action and can be dangerous intake due to increase toxicity

38
Q

hyperthyroidism aka secondary hypothyroidism

A

over production of thyroxine-thyroxine level increase -TSH level drops

39
Q

causes of over production of thyroxine

A

Graves disease aka autoimmune- toxic multi nodular goitre- solitary toxic nodule

40
Q

combined therapy of T3 and T4

A

complication of toxicity due to overload of T3 and T4 hormones leading to palpitations, tremor and anxiety

41
Q

Graves disease

A

autoimmune condition where antibodies bind and stimulate TSH receptor leadings to smooth goitre
Or antibodies bind to muscles behind eyes- exophthalmos
Or stimulate the growth of soft tissues of shins- pretibial myxoedema

42
Q

signs and symptoms of hyperthyroidism

A

heat intolerance, weight loss and increase appetite, diarrhoea, tremors and palpitations, myopathy, sore eyes and goitre, mood swings.

BRS (28 decks)

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