Physiology - Thyroid Flashcards

1
Q

the thyroid gland is composed of lobules of ………… follicles filled with colloid

a.hexagonal
b.spherical
c.square

A

b.spherical

colloid centre inside round follicle many follicles make up lobule

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1
Q

what are the 2 components required for thyroid hormone synthesis

a.tyrosine and calcium
b.tyrosine and iodine
c.adenosine and iodine
d.adenosine and magnesium

A

b.tyrosine and iodine

tyrosine + iodine —> monoiodotyrosine (MIT)

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2
Q

how does iodide leave the interstitial fluid and enter the follicle cell of the thyroid gland?

a.diffusion
b.active transport
c.cotransport with sodium

A

c.cotransport with sodium

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3
Q

how does iodide travel from the follicle cell into the lumen of the follicle (colloid)

a.diffusion
b.active transport
c.co transport with sodium
d.I/Cl transporter

A

d.I/Cl transporter

Pedrin

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4
Q

what happens to iodide in the colloid

A

iodide oxidised and attached to rings of tyrosines in the thyroglobulin

iodinated ring of one MIT is added to a DIT

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5
Q

what happens after iodinated tyrosine ring is added to another ring

a.endocytosis of thyroglobulin containing t3 and t4 molecules

b.lysosomal enzymes release t3 and t4 from thyroglobulin

c.thyroglobulin protein synthesised in follicle cell then sent to colloid

d.t3 and t4 released into interstitial fluid

A

a.endocytosis of thyroglobulin containing t3 and t4 molecules

correct sequence of events above^

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6
Q

in order to exert full biological activity T….. needs to be converted to T…

a.3 -> 4
b. 4 -> 3

A

b. 4 -> 3

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7
Q

which enzyme is produced in the liver, kidney, thyroid, pituitary and heart and is responsible for local synthesis of t3 and 4 in thyroid, and peripheral synthesis of t3

a.type 1 deiodinase
b.type 2 deiodinase
c.type 3 deiodinase

A

a.type 1 deiodinase

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8
Q

which enzyme is produced in the pituitary, brain, skeletal muscle and brown adipose tissue and is responsible for regulating local t3 production and adding to systemic t3 production

a.type 1 deiodinase
b.type 2 deiodinase
c.type 3 deiodinase

A

b.type 2 deiodinase

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9
Q

which enzyme is produced in the placenta, uterus, brain, fatal tissue, thyroid, kidney and adult liver and is responsible for inactivation of t3 and t4-> rt3

a.type 1 deiodinase
b.type 2 deiodinase
c.type 3 deiodinase

A

c.type 3 deiodinase

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10
Q

what type of intracellular receptor do thyroid hormones bind to?

a.cytoplasmic
b.mitochondrion joined cytoplasmic receptor and nuclear receptor
c.nuclear receptor

A

b.mitochondrion joined cytoplasmic receptor and nuclear receptor

binding causes increased ATP
and change in gene activity
altering structural proteins/ enzyme activity
leading to target cell response
thyroid hormones affect ALL cells in the body

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11
Q

what effect do t3 and t4 have on oxygen consumption

a. increase
b.decrease

A

a. increase

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12
Q

what effect do t3 and t4 have on Basal metabolic rate

a. increase
b.decrease

A

a. increase

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13
Q

what effect do t3 and t4 have on carbohydrate metabolism

a. increase
b.decrease

A

a. increase

increase absorption of glucose
increase glycogenolysis
increased gluconeogenesis

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14
Q

what effect do t3 and t4 have on lipid metabolism

a. decreased lipolysis
b.increased lipolysis

A

b.increased lipolysis

more circulating FFAs, increased FFA oxidation , decreases cholesterol and increases LDL receptor number

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15
Q

what effect do thyroid hormones have on the heart

a.increase HR,CO, increase blood flow to skin

b.decrease HR,CO, decrease blood flow to skin

A

a.increase HR,CO, increase blood flow to skin

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16
Q

what effect do thyroid hormones have on the heart

a.increase HR,CO, increase blood flow to skin

b.decrease HR,CO, decrease blood flow to skin

A

a.increase HR,CO, increase blood flow to skin

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17
Q

what effect do thyroid hormones have on the nervous system

a. increases synaptic activity , enhances effects of sympathetic NS

b.decreases synaptic activity , reduces the effects of the sympathetic nervous system

A

a. increases synaptic activity , enhances effects of sympathetic NS

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18
Q

what regulates the circulating levels of thyroid hormone ?

a.hypothalamus
b.pituitary
c.hypothalamus and pituitary

A

c.hypothalamus and pituitary

19
Q

what substance released from the hypothalamus stimulates the release of TSH from the anterior pituitary whih in turn stimulates the thyroid gland to release T3 and T4

a.CRH
b.FSH
c.TRH
d.TSH

A

c.TRH

20
Q

is released from the anterior pituitary in response to TRH from the hypothalamus

a.TSH
b.CRH
c.T3 and T4
d.TRH

A

a.TSH

21
Q

what effect does stress have on secretion of t3 and t4 from the thyroid gland

.a. increase
b.decrease

A

b.decrease

22
Q

what effect does cold have on secretion of t3 and t4 from the thyroid gland

.a. increase
b.decrease

A

a. increase

23
Q

what effect does TSH have on iodine binding at the thyroid gland

a.increase
b.decrease

A

a.increase

24
Q

what effect does TSH have on thyroglobulin synthesis and secretion into colloid at the thyroid gland

a.increase
b.decrease

A

a.increase

25
Q

what effect does TSH have on t3 and t4 synthesis at the thyroid gland

a.increase
b.decrease

A

a.increase

26
Q

what effect does TSH have on number and size of follicular cells at the thyroid gland

a.increase
b.decrease

A

a.increase

27
Q

what effect does TSH have on blood flow at the thyroid gland

a.increase
b.decrease

A

a.increase

28
Q

a disorder at the level of the hypothalamus would be referred as

a. primary
b.secondary
c.tertiary

A

c.tertiary

29
Q

a disorder at the level of the pituitary would be referred as

a. primary
b.secondary
c.tertiary

A

b.secondary

30
Q

a disorder at the level of the endocrine gland would be referred as

a. primary
b.secondary
c.tertiary

A

a. primary

31
Q

the failure of the thyroid gland to respond to TSH is known as

a. primary hypothyroidism
b.secondary hyperthyroidism
c.tertiary hypothyroidism
d.primary hyperthyroidism

A

a. primary hypothyroidism

caused by

Thyroiditis
severe iodine defficinecy
severe deficiency of synthesis hormones
removal or destruction of thyroid gland

32
Q

reduced negative ffedback in primary hypothyroidism causing elevated TSH in primary hypothyroidism causes which symptom

a.short height
b.goitre
c.impaired brain development

A

b.goitre
thyroid enlarges

33
Q

defficient TSH production is known as

a. primary hypothyroidism
b.secondary hypothyroidism
c.tertiary hypothyroidism
d.primary hyperthyroidism

A

b.secondary hypothyroidism

34
Q

in which type of hypothyroidism does thyroid atrophy occur

a. primary hypothyroidism
b.secondary hypothyroidism
c.tertiary hypothyroidism
d.primary hyperthyroidism

A

b.secondary hypothyroidism

deficient TSH production

35
Q

in which type of hypothyroidism is there deficient TSH secretion due to deficient TRH secretion

a. primary hypothyroidism
b.secondary hypothyroidism
c.tertiary hypothyroidism
d.primary hyperthyroidism

A

c.tertiary hypothyroidism

36
Q

what are the consequences of hypothyroidism

A

short stature
brain, bone and other development seriously impaired

37
Q

what is the most common cause of hyperthyroidism

a.thyroiditis
b.severe iron defficiency
c.graves disease
d.thyroid adenoma

A

c.graves disease

38
Q

graves disease pathophysiology

A

antibody producing cels produce thyroid stimulating antibodies
the thyroid rleases excess t3 and t4
hyperthyroidism

39
Q

cold intolerance, dyspnea , fatigue, weakness, weight gain are symptoms of ..

a.hypothyroidism
b,hyperhtyroism

A

a.hypothyroidism

40
Q

hyperactivity, sweating , palpatations, diarrhoea weight loss are symptoms of ..

a.hypothyroidism
b,hyperthyroidism

A

b,hyperthyroidism

increases sympathetic

41
Q

bradycardia , goitre, dry skin, peripheral edema, and puffy face are signs of

a.hypothyroidism
b,hyperthyroidism

A

a.hypothyroidism

42
Q

tachycardia,tremor,goitre, moist skin, proximal muscle weakness are signs of

a.hypothyroidism
b,hyperthyroidism

A

b,hyperthyroidism

43
Q

what condition has high TRH and TSH but low T4

a.primary hypothyroidism
b.secondary hypothyroidism
c.tertiary hypothyroidism
d.graves disease

A

a.primary hypothyroidism

problem at level of thyroid gland

44
Q

what condition has high TRH but low TSH and T4

a.primary hypothyroidism
b.secondary hypothyroidism
c.tertiary hypothyroidism
d.graves disease

A

b.secondary hypothyroidism

problem at level of pituitary

45
Q

what condition has low TRH TSH and T4

a.primary hypothyroidism
b.secondary hypothyroidism
c.tertiary hypothyroidism
d.graves disease

A

c.tertiary hypothyroidism

provblem at level of hypothalamus

46
Q

what condition has low TSH and TRH but high T4

a.primary hypothyroidism
b.secondary hypothyroidism
c.tertiary hypothyroidism
d.graves disease

A

d.graves disease
hyperthyroidism antibodies stimulate thyroid to produc t4