Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Endocrinology > The Thyroid Gland > Flashcards

The Thyroid Gland Flashcards

1
Q

what vertebral level is the thyroid gland located at

A

between C5 and T1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

what is the function of the thyroid gland

A

synthesises the thyroid hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

what are the two thyroid hormones that are physiologically active

A

T3 (triiodothyronine)

T4 (thyroxine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

what are the two cell types that make up the thyroid gland

A

C (clear) cells

Follicular cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is the function of C cells

A

secrete calcitonin (Ca2+ regulating hormone)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what is the function of follicular cells

A

they manufacture the enzymes that make thyroid hormones and surround hollow follicles

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

thyroid follicles are special structures what are their walls made out of

A

follicular cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

what composes the centre of thyroid follicles

A

colloid (a sticky glycoprotein matrix) which contains 2-3 months supply of TH

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

once follicular cells have made enzymes and thyroglobulin where are these products stored

A

The enzymes and thyroglobulin are packaged into vesicles and exported from the follicular cells into the colloid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

follicular cells also actively concentrate iodide from the plasma, where do they transport this to

A

into the colloid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

when iodide is transported into the colloid what does it combine with

A

tyrosine residues to form thyroid hormones

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

where are both tyrosine and iodide derived from

A

the diet

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

how is iodide transported from the plasma into follicular cells

A

via Na+/I- transporter

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

why does iodide get coupled to Na+ to enter the follicular cells

A

as the coupling to Na+ enables the follicular cells to take up iodide against a concentration gradient

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what is the role of the pendrin transporter

A

transports iodide into the colloid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

what inhibits iodide transport into the thyroid gland

A

thiocyanates

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

what are thiocyanates

A

compounds formed from detoxification of cyanide (common origin is cigarette smoke)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

what is the function of thyroid peroxidase

A

catalyses the addition of iodide to tyrosine residues in thyroglobulin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

what is the product of the addition of one iodine to tyrosine

A

MIT (monoiodotyrosine)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

what is the product of the addition of two iodine to tyrosine

A

DIT (diiodotyrosine)

21
Q

what is the product of MIT + MIT

A

triiodothyronine or T3

22
Q

what is the product of DIT + DIT

A

tetraiodothyronine or thyroxine T4

23
Q

what happens to portions of the colloid in response to TSH

A

portions of the colloid are taken back up into the follicular cell by endocytosis

within the cells they form vesicles which contain proteolytic enzymes that cut the thyroglobulin to release thyroid hormones

24
Q

can T3 ad T4 pass across the follicular cell membrane

A

yes as they are lipid soluble

25
Q

T3 and T4 can pass across the follicular cell membrane into the plasma where they bind to plasma proteins, what protein do thy mainly bind to

A

thyroxine binding globulin

26
Q

both T3 and T4 circulate in the plasma true or false

A

true

27
Q

what percentage of T3 and T4 circulating in plasma is bound to plasma protein

A

99.8%

28
Q

thyroxine binding globulin has a particularly high affinity for what TH

A

T4

29
Q

why has T4 got a higher half life than T3

A

as TBG has a high affinity for T4 and only releases it slowly into the plasma this gives it a longer half life than T3

30
Q

what TH is present in higher levels in the plasma T4 or T3

A

50x more total (free+bound) T4 in plasma than T3

31
Q

90% of TH binding to TH receptors inside cells is T3, why is this

A

The TH receptor has a much higher affinity for T3 than T4 making T3 3-5 times more physiologically active than T4

32
Q

what is TRH

A

thyroid releasing hormone

33
Q

what is somatostatin also known as

A

growth hormone inhibiting hormone

34
Q

what effects do glucocorticoids have on TSH and T4/T3

A

GLucocorticoids inhibits TSH and conversoion of T4 to T3

35
Q

what is TSH

A

thyroid stimulating hormone

36
Q

what effects does somatostatin have on TSH

A

Somatostatin inhibits Thyroid stimulating hormone

37
Q

thyroid hormone is required for foetal brain development what can deficiency result in

A

congenital hypothyroidism

38
Q

where do we get iodine from

A

from the diet

39
Q

what is hyperthyroidism

A

is an overactive thyroid, where the thyroid gland produces too much thyroid hormones

40
Q

what is Grave’s disease

A

Grave’s disease is a cause of hyperthyroidism, it is an autoimmune disease where the body produces antibodies that mimic TSH and continually activate the thyroid gland

41
Q

why are [TSH]plasma levels low in hyperthyroidism

A

because there is increased release of thyroid hormone which switches off TSH release from the anterior pituitary

42
Q

what is a thyroid adenoma

A

hormone secreting thyroid tumour (can cause hyperthyroidism)

43
Q

what are the symptoms of hyperthyroidism

A

increased metabolic rate and protein catabolism:weight loss

increased metabolic rate causes heat production:heat intolerance

increased protein catabolism:muscle weakness

altered nervous system function:hyperexcitable reflexes and psychological disturbances

elevated cardiovascular function, TH is permissive to epinephrine and B receptors:

44
Q

what is Hashimoto’s disease and what does it cause

A

it is an autoimmune attack of the thyroid gland and can cause hypothyroidism

45
Q

how much iodine do we have to get from our diet per year in order not to become deficient

A

50mg

46
Q

what can a deficiency in dietary iodine result in

A

hypothyroidism

47
Q

what are the symptoms of hypothyroidism

A

decreased metabolic rate and heat production: weight gain/cold intolerance

disrupted protein synthesis: brittle nails/thin skin

altered nervous system function: slow speech/reflexes.fatigue

reduced cardiovascular function: slow heart rate/weaker pulse

48
Q

what is goitre

A

significant enlargement of the thyroid gland

49
Q

list 5 functions of thyroid hormone

A
  1. raises metabolic rate and promotes thermogenesis
  2. increases hepatic gluconeogenesis
  3. net increases in proteolysis
  4. net increase in lipolysis
  5. critical for growth

Endocrinology (25 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions