4.3 Endocrine Flashcards Preview

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Flashcards in 4.3 Endocrine Deck (40)
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1
Q

TSH stimulates all activities of the ______ except?

A

thyroid EXCEPT storage

2
Q

TSH stimulates what 4 main activities?

A

1) thyroglobulin synthesis in follicle
2) iodid trapping by follicle
3) conversion of iodide to iodine (peroxidase)
4) iodination of tyrosines of thyroglobulin

3
Q

storage of iodinated thyroglobulin is in?

A

colloid

4
Q

TSH made/secreted by?

A

anterior pituitary

targets thyroid follicle

5
Q

what AA is iodated to make T3 and T4?

A

tyrosine

6
Q

iodide or iodine is used to iodinate thyroglobulin?

A

iodiNe

7
Q

Why doesn’t TSH promote storage?

A

bc once we make T3 or T4 we don’t want them to STAY in the colloid, we want them taken back up by the follicle and released into blood

8
Q

What is MIT?

A

monoiodotyrosine= tyrosine with ONE iodine bound

9
Q

what is DIT?

A

diiodotyrosine= tyrosine with TWO iodines bound

10
Q

both MIT and DIT remain linked to thyroglobylin while in the ____?

A

colloid
*Not until thyroglobulin is taken out of colloid back into follicle by penocytosis does LYSOSOMAL PROTEASE start breaking bonds to release T3 or T4

11
Q

roles of peroxidase?

A

1) convert iodide to iodine
2) coupleing of MIT and DIT into T3
and DIT and DIT into T4
3)attachment of iodine to thryroglobulin

12
Q

TSH > pinocytosis of _______ > degradation by ________ > T4 and T3 released into cytoplasm and then into circulation

A
  1. TSH
  2. pinocytosis of colloid droplets
  3. degradation by lysosomal protease
  4. T4 and T3 released into cytoplasm
  5. T4 and T3 into circulation
13
Q

T4 conversion to T3 happens where?

A

liver

14
Q

90% of intracellular (in cell) thyroid is?

A

T3

15
Q

90% of thyroid hormone coming out of the thyroid is?

A

T4

16
Q

thyroid hormones are _____ of cellular activity? explain

A

modulators

*increase metabolic activity and play essential role in growth and development

17
Q

any issue with iodine causes?

Explain how

A

global detramental affects bc thyroid hormones affect so many cells
*hypothyroidism
=decrease iodine > can’t make T3/T4 > decrease - feedback inhibition of hypo and pit > increase TSH levels > excessive stimulation of thyroid = goiter

18
Q

thyroid hormones diffuse through cells membranes why?

A

so they canbind on chromatin and alter transcriptions, translation, and protein synthesis

19
Q

thyroid hormones bind to receptors on?

A

chromatin

20
Q

explain the regulation of thryoid hormone?

A

> TRH > anterior pituitary > TSH > thyroid > T4/T3

***- feedback important

21
Q

what is the most important regulator of thyroid hormone

A

negative feedback

22
Q

the cold stimulus of the hypothalamic temperature regulatory center influences what function?

A

thyroid function

  • in human infants and other mammals (minimal or nonexistent in adults)
  • hypothalamic secretion of TRH is initiated via neuroendocrine reflex involving peripheral cold receptors
23
Q

neuroendocrine reflex involves?

A

peripheral cold receptors of the hypothalamis; can initiate TRH secretion

24
Q

how does stress affect thyroid hormone secretion?

A

stress increases cortisol > inhibition of hypothalamus > decrease TRH, TSH, and T4/T3

25
Q

main role of cortisol

A

regulate hormone levels in the blood (brings nutrients out of storage)
*also inhibits TSH secretion

26
Q

hypothyroidism

A

inadequate secretionof thyroid hormones

27
Q

hyperthyroidism

A

oversecretion of thyroid hormones

28
Q

both hyperthyroidism and hypothyroidism results in?

A

goiter

29
Q

what is goiter

A

thyroid hypertrophy

30
Q

hypothyroidism causes

A

1) tumor = compressing some structure within the hypothalamus/ ant pit/ thyroid axis
2) iodine deficiency (most common)
- –usually endemic to a particular region of the world

31
Q

how does USA avoid endemic goiter?

A

we put iodine in salt to avoid hypotheyroidism

32
Q

effects of hypothyroidism?

A
decreasedmetabolic rate
less heat production
proteun synthsis
nutrient utilization
oxygen consumption
synaptic acitivty
33
Q

general symptoms of hypothyroidism?

A

weight gain

decreased cold tolerance, growth rate, repisration, heart rate, cardiac output, altertness

34
Q

why would hypothyroidism decrease tolerance to cold?

A

bc lower metabolic rate so less heat production

35
Q

what is cretinism?

A

hypothyroidism in children/infants

36
Q

why is cretinism such a big deal?

A

child becomes short of stature, gains weight and can have mental retardation issues if not treated

37
Q

what does cretinism effect orally?

A

delayed primary tooth eruption, enamel hypoplasia, macroglossia
*large tongue

38
Q

define macroglossia

A

enlarged soft tissue; accumulation of mucopolysaccarrides in soft tissue

39
Q

what is myxedema?

A

hypothyroidism in adults; enlarged soft tissue

40
Q

hypothyroidism in adults symptoms?

A
  • myxedema
  • dry and/or loss of hair
  • subnormal body temperature, hoarse voice, muscle weakness, slow tendon jerk