week 3-L2-thyroid gland

Question 1

thyroid gland labels top to bottom

Answer 1

thyroid cartilage, thyroid gland, isthmus and pyramid

Question 2

thyroid gland interior structures

Answer 2

follicles, follicular cells and colloid + parafollicular cells

Question 3

dangers of thyroidectomy

Answer 3

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

Question 4

recurrent laryngeal nerve function

Answer 4

supply the vocal cords

Question 5

parathyroid glands

Answer 5

embedded in thyroid and control calcium levels

Question 6

thyroid gland embryology

Answer 6

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

Question 7

problems with thyroid glands development

Answer 7

may not develop at all or may not completely descend

Question 8

thyroid gland mechanism to TSH

Answer 8

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

Question 9

T3 formation

Answer 9

coupling between DIT and MIT

presence of 3,5,3 iodine

Question 10

T4 formation

Answer 10

coupling between 2 DIT molecule

presence of 3,5,3,5 iodine

Question 11

T4 aka

Answer 11

thyroxine

Question 12

which is the main hormone product in the thyroid gland

Answer 12

thyroxine or T4

Question 13

why is T4 the main hormone product?

Answer 13

can be deiodinated to T3, its bioactive form

Question 14

deiodination of T4/ thyroxine

Answer 14

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

Question 15

circulating T3

Answer 15

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

Question 16

plasma protein bound to T3 and T4

Answer 16

thyroid-binding globulin
albumin
prealbumin

Question 17

are plasma bound T3 and T4 active

Answer 17

no oney unbound components are active

Question 18

where is TG found

Answer 18

only in the thyroid

Question 19

where is TGB found

Answer 19

in the circulation

Question 20

% T3 and T4 unbound and what does it show?

Answer 20

0.05 T4 and 0.5 T3, most thyroid hormone are inactive

Question 21

T3 and T4 mechasnim of action

Answer 21

T4 conversion to T3 and T3 alter gene expression

Question 22

cretinism

Answer 22

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

Question 23

how is TSH measure in newborn

Answer 23

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

Question 24

thyroid hormone actions

Answer 24

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

Question 25

T4 half life

Answer 25

7-9 days

Question 26

T3 half life

Answer 26

2 days

Question 27

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

Answer 27

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

Question 28

overreactive thyroid or under reactive thyroid more common?

Answer 28

same

Question 29

primary hypothyrodism

Answer 29

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

Question 30

common forms of autoimmune thyroid disease

Answer 30

Hashimoto thyroiditis and Graves's disease

Question 31

what does presence of 1 autoimmune disease imply

Answer 31

may increase the risks of other autoimmune diseases

Question 32

signs and symptoms of hypothyrosidm

Answer 32

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

Question 33

drugs for primary hyperthyrodism

Answer 33

levothyroxine

Question 34

mechanism of action of levothyroxine

Answer 34

production of T4 as alternative to be deiodinated

Question 35

dosing of levothyroxine

Answer 35

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

Question 36

potential complication of to levothyroxine

Answer 36

minor-weight loss or headache | major-heart attack and rapid heart rate

Question 37

why no use Liothyroxine

Answer 37

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

Question 38

hyperthyroidism aka secondary hypothyroidism

Answer 38

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

Question 39

causes of over production of thyroxine

Answer 39

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

Question 40

combined therapy of T3 and T4

Answer 40

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

Question 41

Graves disease

Answer 41

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

Question 42

signs and symptoms of hyperthyroidism

Answer 42

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