EX 2; Thyroid Gland Flashcards

1
Q

What is the gross anatomy of the thyroid

A
2 lobes
located inferior to the larynx
one of the largest endocrine glands
4 cm long/wide
20 grams
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2
Q

What is the vascularization of the thyroid gland

A

more capillaries per gram than the kidney

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3
Q

The internal structure of the thyroid consists of what

A

hollow follicles formed by spheres of epithelial cells; follicles are filled with colloid, lots of protein

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4
Q

The follicular cells of the thyroid regulate production of what

A

two iodine-containing hormones

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5
Q

What is thyroid hormone synthesis stimulated by

A

TSH, which comes from the pituitary

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6
Q

Iodide is transported into follicular cells and then does what

A

diffuses into the colloid

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7
Q

Follicular cells also synthesize this, which is exocytosed into colloid

A

thyroglobulin; lots of tyrosine

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8
Q

Iodidie oxidized by this and is linked to thryoglobulin; attaching iodide to tyrosine creating MITs and DITs

A

thyroid peroxidase

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9
Q

The mono-iodo-tyrosine and di-iodo-tyrosie combine to form what

A

MIT + DIT = T3

DIT + DIT = T4

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10
Q

The thyroid hormone stored in colloid is attached to thyroglobulin, why is this necessary

A

the protein backbone is not lipid soluble, so it traps the hormone

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11
Q

What three additional actions does TSH stimulate

A

stimulates iodide uptake
protein synthesis
mitosis in follicular cells; hypertrophy and hyperplasia

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12
Q

Thyroglobulin droplets are pinocyotsed into follicle cells and the droplets fuse with what and what occurs

A

lyosomes and T3 and T4 are released by lysosomal hydrolysis and diffuses into capillaries

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13
Q

10% of secreted thyroid hormone is what variety

A

T3

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14
Q

80% of T4 is converted to T3 in which organs

A

liver and kidney (and certain target cells)

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15
Q

Where are the receptors for thyroid hormone located and what are the different forms

A

they are in most cells of the body

α and β forms

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16
Q

Expression of receptor isoforms differs in respect to what two things

A
stage of development (α first)
target tissue (regulate and stimulate cell metabolism)
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17
Q

These two things combined regulate gene transcription

A

dimerized receptors + TH

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18
Q

Thyroid hormone is used to stimulate what

A

metabolism

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19
Q

thyroid hormone stimulates cellular metabolism by increasing the activity of what three things

A

Na/K-ATPase activity
increases substrate availability
produces heat

20
Q

What does thyroid hormone do to the mitochondria

A

increases size and number

21
Q

Insufficient TH during fetal development causes what condition

A

cretinism

22
Q

True or False

diseases of the thyroid gland are the most common of endocrine diseases

A

True

23
Q

How common is thyroid disease in women and in men

A

2-5% in women (childbearing years most common)
0.5% of men
twice as many people have thyroid disease than the number of people diagnosed

24
Q

What is the primary cause of hypothyroidism

A

a primary defect in the thyroid gland

95% due to iodine deficiency

25
Q

What are three consequences of an iodine deficiency

A

insufficient production of TH
lack of negative feedback
growth of goiter because hypertrophy or hyperplasia of follicular cells

26
Q

Hypothyroid due to an iodine deficiency was primarily reversed due to what for additive

A

iodized salt

27
Q

This is also known as Hashimoto’s, which affects the enzymes synthesizing thyroid hormone

A

autoimmune thyroiditis

28
Q

What two additional primary defects can lead to hypothyroidism

A

damage or destruction due to surgery/radiation, etc.

dysfunction associated with other illness

29
Q

What is a second defect that can result in hypothyroid

A

problem in the pituitary; release or receptor issue

30
Q

What are some mild symptoms of hypothyroid

A

cold sensitivity
low metabolism
weight gain

31
Q

What are some moderate symptoms of hypothyroid

A

fatigue
poor circulation
GI/mental function is sluggish

32
Q

What are some severs symptoms of hypothyroid

A

myxedema due to accumulation of glycosaminoglycans in the ECF

33
Q

What are four primary defects that can cause hyperthyroid or thyrotoxicosis

A

thyroid tumor
Graves disease
thyroiditis
thyrotoxicosis facitia

34
Q

This is when antibodies to TSH receptor stimulate the gland, the feedback mechanism is disrupted, and is more common in women

A

Grave’s disease

35
Q

This is when too much thyroid hormone due to ingesting of endogenous thyroid hormone

A

thyrotoxicosis factitia

36
Q

What are four symptoms of hyperthroid

A

abnormal levels of circulating hormone
goiter
metabolic and nervous system symptoms; upregulation
ocular symptoms; fat pad behind eye is bulging

37
Q

What are some options for treatment of hyperthyroid

A

surgically/radioactivity destroy the gland

anti-thyroid drugs

38
Q

What are some dental problems associated with hypothyroid

A

abnormal response to drugs; increased sensitivity
myxedema; extra CSF
diminished cardiac and respiratory functions

39
Q

What are some dental problems associated with hyperthyroid

A

early eruption of teeth
must avoid catecholaminergic drugs; sensitive to epinephrine, sympathetic already on “high alert”
thyroid storm
salivary gland damage due to radiation treatments

40
Q

Thyroid hormone up regulates these receptors

A

beta adrenergic

41
Q

Upregulation of beta adrenergic receptors by thyroid hormone increases sensitivity to what

A

catecholamines

42
Q

When the thyroid hormone up regulates beta adrenergic receptors, what does this due to the sympathetic system

A

involved with the sympathetic system; NE and E

increasing HR and dilating respiration

43
Q

The thyroid hormones also regulate production of this

A

GH

44
Q

Thyroid hormone is important for this development

A

CNS development and function

45
Q

Thyroid hormone regulates what in adults

A

normal neural responses in adults; hence why if you have limited TH in fetal development = cretinism