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MET 2 > Thyroid > Flashcards

Thyroid Flashcards

1
Q

What makes up mono-iodotyrosine

A

Tyrosine with one iodine

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2
Q

What is the proper name for T3

A

Liothyronine

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3
Q

What is the proper name for T4

A

Levothyroxine

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4
Q

Describe the dimensions of the thyroid gland

A

2cm thick and 4cm long

Right lobe is usually larger

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5
Q

Which gland has the highest blood supply per g in the body

A

Thyroid

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6
Q

Are the thyroid or parathyroid glands more anterior

A

Thyroid

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7
Q

What is meant by thyroid follicle

A

Lots of thyroidal epithelium surrounding each colloid

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8
Q

Describe the epithelium of the thyroid follicles

A

Cuboidal when inactive

Columnar when active

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9
Q

How many follicles are there per lobule

A

20-40

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10
Q

How many arteries are there per lobule

A

1

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11
Q

VERY briefly state how thyroid works to release thyroid hormones

A

Traps iodine and attaches it to protein
Protein can then be broken down
Hormones can then be released

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12
Q

What receptor receives signals from the pituitary gland

A

TSH receptor

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13
Q

What protein is used to oxidise the iodide int he thyroid

A

Thyroid peroxidase (TPO)

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14
Q

What is the oxidising agent for iodide in the thyroid? How is it formed

A

Hydrogen peroxidase

DUOX1 and DUOX2

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15
Q

What travels into the thyroid follicular cell via NIS

A

2 sodiums and an iodide

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16
Q

What is NIS

A

Sodium iodide sympoter

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17
Q

What transports iodide from the thyroid follicular cell to the colloid

A

pendrin PDS

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18
Q

What is the role of ER and golgi body in the thyroid follicular cell

A

Gives thyroglobulin

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19
Q

What is used to recycle iodide

A

Iodotyrosine dehalogenase 1

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20
Q

What % of the thyroid hormones produced are T4

A

80-90%

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21
Q

What is the role of cAMP in controlling thyroid follicular cells

A

Regulates NIS and moves it to the membrane
Upregulates di-iodinase 2 production which converts T4-T3
Upregulates thyroglobulin
Upregulates oxidising agents
Upregulates digestion of thryoglobulin

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22
Q

What molecule must be removed to convert T4 to T3

A

Iodide

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23
Q

What family of enzymes removes iodides from T4

A

Deiodinases

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24
Q

Which specific deiodinases convert T4 into T3

A

D1 and D2

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25
Q

What does D3 do

A

Converts T4 into the inactive reverse T3

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26
Q

Where is D1 most expressed

A

Liver, kidney and muscle

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27
Q

Where is D2 most expressed

A

Brain and pituitary

28
Q

In what condition is D2 upregulated and why

A

Hypothyroidism

T4 levels will fall, but D2 is upregulated so that the T4 that is produced in all converted into T3

29
Q

How is thyroid function regulated

A
  • Inverse relationship between iodine levels in the thyroid and rate of hormone formation
30
Q

What is released from the hypothalamus to stimualte pituitary to secrete TSH

A

TRH

31
Q

How are T4 and T3 transported through the body

A

Via thyroid binding globulin

32
Q

What kind of receptor is the thyroid hormone receptor

A

Nucleus receptor

33
Q

Describe the structure of the thyroid hormone receptor

A
  • 2 TRs stuck together with a corepressor stuck to it
34
Q

What happens when T3 binds to one of the receptor units

A

Corepressor leaves
Dimer breaks up
Attracts co-activator
This activates transcription

35
Q

In general, what is effect of thyroid hormones on the body

A

Increases basal metabolic rate

36
Q

Define hyperthyroidism

A

Over active thyroid

37
Q

Define thyrotoxicosis

A

State of having too much thyroid hormone

38
Q

What are the effects on the cardiovascular system when the person has hyperthyroidism

A

Increased metabolic rate, so produces heat
To get rid of heat, more blood goes to the skin
HR and CO increased
Prone to AF

39
Q

What metabolic changes can be expected in somebody with hyperthyroidism

A
  • Increased appetite
  • Heat intolerance
  • Protein and lipid degradation
  • Weight loss and myopathy
  • Accelerated insulin turnover
  • Hyperglycaemia
40
Q

Why is T1D and hyperthyroidism linked

A

Both autoimmune

41
Q

What is the effect of hyperthyroidism on the nervous system

A

Anxious, cross

Increases threshold of seizures

42
Q

Why does Graves disease lead to

A

Autoimmune process affecting thyroid gland affects the eyes and causes cytokine release at back of the eyes

43
Q

Name 2 signs of hyperthyroidism that can be seen on the skin

A

Plummer nails

Pretibial myxoedema

44
Q

What is the effect of hyperthyroidism on the GI tract

A

Weight loss
Increased motility
Increased appetite
Transaminitis

45
Q

What is transaminitis

A

Damage to liver leading to elevated liver enzymes

46
Q

What is the effect of hyperthyroidism on bones

A

Accelerated osteoclast activity
Hypercalcaemia
Osteroporosis

47
Q

What are the effects of hyperthyroidism on haematological system

A

Pernicious anaemia

B12 deficiency

48
Q

What are the effect of hyperthyroidism on the reproductive system

A

Oligomenorrhoea
Gynecomastia
Erective dysfunction

49
Q

What is glynecomastia

A

Breakdown of testosterone

50
Q

Define Grave’s disease

A

Autoimmune condition leading to invasion of thyroid gland by B and T cells

51
Q

How do the antibodies against TSH receptor act during Graves disease

A

Act in same way as TSH so stimulate an overexpression in normal function of the thyroid

52
Q

What proteins do antibodies target in Graves disease

A

TSH receptor
Thyroid peroxidase
Thyroglobulin

53
Q

Name 4 risk factors for Grave’s disease

A
  • HLA status
  • Infection
  • Stress
  • Female sex
54
Q

Why do pregnant women often have thyrotoxicosis

A

Hcg acts on the TSH receptor- transcient thyrotoxicosis

55
Q

What are the key hormone level differences in hyperthyroidism

A

Elevated T4 and T3

Suppressed TSH

56
Q

What thionamide drugs are most commonly used to manage hyperthyroidism

A

Propylthiouracil

Carbimazole

57
Q

What changes to the skin happen in hypothyroidism

A
  • Put on weight
  • Skin dries out
  • Hair dries
  • Lose outer third of eyebrow
58
Q

What cardiovascular changes in a person with hypothyroidism

A

Sinus bradycardia

J waves of hypothermia

59
Q

Is there more or less LDL cholesterol in hypothyroidism

A

More

60
Q

What changes occur in the GI tract in people with hypothyroidism

A

Reduced appetite

Constipation

61
Q

Are reflexes slow or hyper in hypothyroidism

A

Slow

62
Q

What changes occur in the renal system in hypothyroidism

A

Reduced GFR

Mild hyponatraemia

63
Q

What haematological changes occur in hypothyroidism

A

Normochromic normocytic anaemia

64
Q

Is GLUT4 stimulated decreased or increased in hypothyroidism

A

Decreased

65
Q

What endocrine changes occur in hypothyroidism

A

Delayed puberty, reduced libido, erectile dysfunction

66
Q

What characterises Hashimotos disease

A

Antibodies against thyroid oxidase

67
Q

What is endemic goitre

A

Not making enough thyroid hormone so the pituitary releases more TSH stimulating it to grow

MET 2 (32 decks)

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