endocrinology lecture 2 Flashcards

1
Q

where is the thyroid gland found? what connects it?

A

either side of the trachea

connected by isthmus

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2
Q

what is the thyroid gland organized into?

A

follicles

balls of follicular cells, single layer forms ball

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3
Q

what is found in the middle of a thyroid follicle?

A

colloid

fluid filled inner portion filled with proteins

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4
Q

the colloid fluid is made by __________

A

made by follicular cells

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5
Q

follicular cells regulate the production of which two iodine-containing hormones?

A

T3 and T4

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6
Q

thyroid hormones are ____ based hormones

A

lipid soluble, amine based hormones

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7
Q

why is a colloid storage mechanism needed in the thyroid?

A

prevents diffusion of the hormones out of the cells

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8
Q

______ stimulates the thyroid gland to take up iodine with sodium (Na+)

A

TSH

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9
Q

follicular cells also secrete __________, which has many tyrosine residues

A

thyroglobulin

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10
Q

what is iodine oxidized by? what happens after oxidation?

A

oxidized by THYROID PEROXIDASE

linked to thyroglobulin (on the tyrosine residues)

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11
Q

what molecules combine to form T3 and T4?

A

MITs and DITs

mono or di thyrotyrosine

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12
Q

thyroid hormone is stored in colloid attached to __________

A

thyroglobulin

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13
Q

what stimulates thyroid hormone release?

A

TSH (from pituitary gland)

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14
Q

droplets of thyroglobulin fuse with ______ and T3 & T4 are released

A

lysosomes

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15
Q

_______ of T4 is converted to T3 in the liver and kidneys

A

80%

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16
Q

thyroid hormone exerts a negative feedback effect on the secretion of ___ and ___

A

TRH and TSH

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17
Q

what are the forms of thyroid hormone receptors? what are they encoded by?

A

alpha and beta forms

encoded by 2 different genes

18
Q

a dimerized receptor + TH will regulate ____________

A

gene transcription

19
Q

how does TH stimulate cellular metabolism?

A

1) increase Na/K-ATPase activity
2) increase substrate availability
3) produces heat

20
Q

t/f: Thyroid hormone can upregulate beta-adrenergic receptors

A

true

21
Q

the effect of up regulating beta-adrenergic receptors leads to an increased sensitivity to ___________

A

catecholamines

NE and E

22
Q

TH is important for neuron _______ and _______

A

growth and development

23
Q

insufficient TH during fetal development causes ________

A

cretinism

24
Q

what are the most common endocrine diseases?

A

diseases of the thyroid gland

25
Q

both hypo-, and hyperthyroidism can lead to ______ development

A

goiter

26
Q

what is the consequence of hyper- or hypothyroidism?

A

Thyroid hormone normally inhibits TSH & TRH

  • too much, or too little, of TH will disrupt this balance
27
Q

Hypothyroidism is most often caused by what?

A

a primary defect in the thyroid gland

28
Q

T/F: 95% of the defects that cause hypothyroidism are due to a Iodine deficiency

A

True

29
Q

what effect does a lack of thyroid hormone have on TRH and TSH?

A

causes an increase in TRH and TSH due to a lack of feedback inhibition

30
Q

why does hypothyroidism cause a goiter?

A

unregulated TSH stimulation (due to lack of TH release)

31
Q

what are the effects of cretinism? (fetal iodine deficiency)

A

short stature

mental retardation

32
Q

besides iodine deficiency, what are the other defects leading to hypothyroidism?

A

A) autoimmune thyroiditis

B) damage or destruction of gland

C) dysfunction associated with other illness

33
Q

what are the MILD symptoms/consequences of hypothyroidism?

A
  • related to metabolic effects of TH

- sensitive to cold, slight weight gain

34
Q

what are the MODERATE symptoms of hypothyroidism?

A
  • enough of a deficiency to cause lack of catacholamine response
  • fatigue, reduction in: blood flow, skin tone, GI & mental function
35
Q

the SEVERE effects of hypothyroidism include _______ due to an accumulation of what?

A

myxedema (bloating of soft tissue)

accumulation of glycosaminoglycans (GAGs) in ECF

36
Q

t/f: hyperthyroidism is more common than hypothyroidism

A

false

37
Q

what are the primary defects that cause hyperthyroidism?

A

1) thyroid tumor
2) Graves disease (autoimmune)
3) thyroiditis (inflammation of Thyroid)
4) thyrotoxicosis factitia (too much TH is EATEN)

38
Q

symptoms/concsequences of hyperthyroidism

A

A) abnrmal concentrations of circulating hormones- high TH, low TSH

B) goiter (only in graves disease)

C) up-regulation of metabolic and nervous systems

D) ocular symptoms

39
Q

how is hyperthyroidism treated?

A

1) surgery, radioactive iodine
2) remove entire gland
3) treat with drugs

40
Q

how do the drugs that treat hyperthyroidism work?

A

they block activity of enzyme in the TH production sequence

41
Q

why is hyperthyroidism of special concerns to dental care

A
  • you must avoid catecholaminergic drugs (their receptors are overly expressed in the body)
  • thyroid storm
  • salivary glands can be damaged after radiation therapy