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physiology > endo 2, thyroid > Flashcards

endo 2, thyroid Flashcards

1
Q

where is the thyroid location

A

inferior to the larynx

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2
Q

does the thyroid have a lot ofvasculature

A

yes, lots

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3
Q

what makes up the thyroid gland

A

series of hollow follicles formed by spheres of epithelial cells filled with colloid

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4
Q

where does the apical and basal surfaces of the epithelial layer of the thyroid face

A

apical faces the colloid

Basal faces the blood supply

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5
Q

other name for the epithelial cells of the thyroid

A

Follicle cells

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6
Q

what does the follicle cells do

A

Regulate the production of the iodine containing thyroid hormones

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7
Q

what do thyroid hormones disolve in

A

lipophilic

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8
Q

where is thyroid hormone synthesized in the Thyroid

A

In the coloid

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9
Q

How is Iodine trasported from the interstitial fluid to the follicle cells

A

Across the basal side using an Na/I transporter

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10
Q

how does Iodine get into the colloid from inside the follicle cells

A

Iodine diffuses down its concentration gradient across the apical membrane into the colloid

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11
Q

where does Thyroglobulin come from

A

follicle cells synth

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12
Q

what is thyroglobulin full of

A

Lots of tyrosine’s for thyroid hormones

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13
Q

what also is exocytosed across the cell membrane into the colloid along with thyroglobulin

A

thyroid peroxidase

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14
Q

what is the action of thyroid peroxidase

A

oxidizes Iodine and links it to thyroglobulin

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15
Q

what is the importance of binding iodine to thyroglobulin

A

creates the concentration gradient needed to import Iodine into the colloid

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16
Q

when 1 iodine binds to tyrosine, it forms

A

Monoiodotyrosine

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17
Q

when 2 iodines bind to tyrosine, it forms

A

Diiodotrosine

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18
Q

how is T3 made

A

when a MIT and a DIT combine

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19
Q

how is T4 made

A

when 2 DIT’s form

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20
Q

where is T3 adn T4 stored

A

In the colloid

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21
Q

what leads to secretion of thyroid hormes

A

TSH

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22
Q

what releases TSH

A

Anterior pituitary in response to TRH

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23
Q

what releases TRH

A

Hypothalamus

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24
Q

where are TSH receptors found

A

In the basal membrane of the follicle cells

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25
Q

secondary action of TSH

A

increase the synthetic activity of the follicle cells

stimulates hyperplasia

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26
Q

what happens when TSH binds to TSH receptor

A

Droplets of colloid containing Thyroglobulin G+T3/T4 are pinocytosed into the follicle

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27
Q

what happens when thyroglobulin bound to T3/T4 is pinocytosed inot the follicle cells

A

fuses with lysosome containing enzymes that clevae T3 and T4 from Thyroglobulin to be released to the cytoplasm
-T3/T4 ultimately diffuse into capillaries and TG is degrated and recycled into new TG

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28
Q

how is Secretion of Thyroid hormones regulated

A

negative feedback at the hypothalamus and pituitary

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29
Q

What Thyroid hormone is secreted more

A

90% of Thyroid hormone is T4

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30
Q

what is more biologically active, T3 or T4

A

T3 is more biologically activated

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31
Q

what happens to the T4 considering it isn’t very biologically activated

A

80% is converted to T3 in the liver and kidney

32
Q

what happens when the extraiodine is removed from T4 to make T3

A

the extra iodide is returned to the colloid

33
Q

why does the body secrete more T4 instead of T3, despite liking T3 more

A

maximize the concentration gradient for free iodine

-ensures iodine is available from Thyroid hormone synthesis

34
Q

what is the enzyme that converts T4 to T3

A

Deiodinases

35
Q

where are the receptors for Thyroid hormone

A

Most are nuclear

36
Q

what are the types of Thyroid hormone receptors

A

Alpha 1 and 2

Beta 1 and 2

37
Q

what sepperates type 1 and type 2 and alpha vs beta thyroid hormone recetpors

A

alpha vs. beta is different genes

1 vs 2 is alternative splicing

38
Q

when does the body produce alpha or beta thyroid hormone receptor

A

alpha: during development of target tissue
BEta: after birth mostly

39
Q

what happens when Thyroid hormone binds to Thyroid hormone receptors

A

Binds to DNA and leads to synthesis of Proteins and enzymes

40
Q

what is the action of Unbound Thyroid hormone receptors

A

bind to DNA to inhibit transcription

41
Q

what is the main effect of Thyroid hormone

A

Metabolism

  • increase Na/K ATPase activity
  • Increase synth of respiratory enzymes
  • Increase substrate availability
  • increase cellular heat production
  • effect mitochondria
  • increase glucosa absorption
  • increase glycogenolysis
  • increase gluconeogenesis
  • increase lipolysis
  • increase protein synth and degradation
42
Q

what are the secondary effects of thyroid hormone

A
  • upregulation of Beta-adrenergic receptors to activate the sympathetic nervous system
  • increase sensitivity to catecholamines in both endo and nervous system
  • regulate Growth hormone production
  • helps with CNS function and development
  • increase cardiac output
43
Q

what effect does Thyroid hormone have on mitochondria

A

activates the UncouplingUndoes the H+ gradient to create heat due to excess energy

44
Q

what is the most common endocrine disease worldwide

A

Thyroid disease, most commonly hypothyroidism

45
Q

How prevelent is thyroid disease

A

2-5% of women

.5% of men

46
Q

what causes thyroid disease

A

disruption of the feedback mech that controls synth of Thyroid hormone

47
Q

does thyroid disease always cause a big problem

A

No, most the time its very mild

48
Q

what does an enlarged thyroid often form

A

A goiter

49
Q

what most often causes hyperthyroidism

A

Caused by a primary defect in the thyroid gland

- iodine deficiency/damage to the gland (95% of the time)

50
Q

why does a goiter form

A

Overstimulation of the thyroid gland by TSH

51
Q

how does Iodiine deficiency lead to a goiter

A

not enought iodine, therefore lack of TH
lack of TH: no negative feedback, so lots of TSH and TRH
lots of TSH leads to goiter

52
Q

how to reverse iodine deficiencies

A

iodized salt

53
Q

what is the problems with iodine deficiency during prenatal development

A 
Moderate deficiency
Cretinism
Miscarriage
Stillbirth
growth/neural development impaired
54
Q

besides iodine deficiency, what else causes hypothyroidism

A

Autoimmune thyoiditis
Damage to glad
Dysfunction associated with other illness
–can’t make TH

55
Q

how to treat hypothyroidism

A

Exogenous TH

56
Q

what are secondary thyroid defect

A

defects of TRH and TSH synth and release

receptor deficits

57
Q

does the thyroid have a problem in a secondary thyroid defect

A

Works fine, just not recieving proper stimulation

58
Q

symptoms of hypothyroidism

A
  • abnormal amounts of TH and TSH
  • Goiter (primary defect)
  • Cretinism/mental retard if during development
  • mild: sensitivity to cold, slight weight gain (may be undiagnosed)
  • moderate: fatigue, reduced bloodflow, changes in skin color, sluggish, Changes in GI motility, mental function
59
Q

causes of moderate hypothyroidism

A

Reduced Beta-adrenergic receptors

60
Q

what is severe hypothyroidism

A

Myxedema

61
Q

symptoms of myxedema

A

Severe bloading due to glycosaminoglycans in the ECF and ICF

- obvious in the face

62
Q

why does SEvere hypothyroidism causes myxdema

A

Normal Thyroid hormones help to regulate the production of GAGs

63
Q

Other name for Hyperthyroidism

A

Thyrotoxicosis

64
Q

why does Hyperthyroidism occur

A

too much TH

65
Q

primary defects that cause hyperthyroidism

A

Thyroid tumors that produce TH without regulation of TSH
Inflammation of glad for excess TH
Graves disease
Thyrotoxicosis Facitiia

66
Q

what is Graves disease

A

Autoimmune disease that causes hyperthyroidism

67
Q

how does Graves disease occur

A

Antibodies produced against TSH
Anti-bodies activate TSH receptor
no feedback regulation of thyroid

68
Q

testing for Graves disease

A

TH concentration high despite TSH and TRH low

More common in own

69
Q

what is Thyrotoxicosis factita

A

hyperthyroidism from consuming excess thyroid hormone via meds or poorly processed meat

70
Q

secondary defects for hyperthyroidism

A

Tumors that secrete TSH without feedback of TH

71
Q

symptoms of Hyperthyroism

A
  • high TH and low TSH
  • Goiter when graves disease from over stimulation of the TSH receptor
  • heat intolerance
  • weight loss
  • increase appetitie
  • sweating
  • hypersensitivity of catecholaminergic rersponse
    = thyroid storm
  • eye problems (exopthalmy, lid lag, decreased visual acuity
72
Q

treatment of hyperthyroidism

A

Remove/destroy gland

take extra TH to avoid hyperthyroidism

73
Q

how do you destroy the thyroid gland

A

Radioactive iodine concentrates in the THyroid gland (also can hurt the salivary glands though)

74
Q

how can drugs can treat hyperthyroidism

A

inhibit ionidation of TYR
block release of TH
ameliorate effects of TH in peripheral tissues

75
Q

how can hypothyroidism lead to dental problems

A

Retarded tooth development and max prognathism
extra response to narcotics and barbituates, since inadqueate response from the sympa system
myxedma for swellen tongue or lips
diminish cardiac and respiratory function due to lack of beat-adrendergic receptor
- hypothermia and hypotension

76
Q

how can hyperthyroidism lead to dental probelms

A

Early eruption of teeth
- malocclusion
hpersenitiy to drugs (catecholaminergic)
Thyroid stome

physiology (32 decks)

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