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z:Physl 210A/B > Endo Lec 4 > Flashcards

Endo Lec 4 Flashcards

(56 cards)

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1
Q

thyroid gland (def.)

A

bi-lobed gland in front of trachea

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2
Q

thyroid gland made of ..

A

-follicles and parafollicular cells

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3
Q

thyroid gland follicles are made of

A

–follicular cells lining the surface and a cavity filled with colloid (gelatinous material)

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4
Q

resting vs. actively secreting follicle

A

actively secreting follicle increases in size

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5
Q

parafollicular cells secrete

A

calcitonin

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6
Q

thyroid follicles secrete

A

T3 & T4

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7
Q

list of thyroid hormones

A
  • T3
  • T4
  • calcitonin
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8
Q

thyroid hormones synthesized from

A

tyrosine and I2

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9
Q

intermediates of thyroid hormones synthesis

A
  • Monoiodotyrosine (MIT)

- Di-iodotyrosine (DIT)

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10
Q

active end products of thyroid hormones synthesis

A
  • Tri-iodothyronine (T3)

- Tetra-iodothyronine or thyroxine (T4)

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11
Q

synthesis of thyroid hormones

A
  1. iodide is cotransported with Na+ into follicle cell and I- diffuses into colloid
  2. Iodide is oxidized and attached to tyrosines in thyroglobulin (TG)
  3. formation of T3 + T4 attached to TG
  4. endocytosis of TG containing T3,T4 molecules into follicle cell
  5. lysosomal enzymes release T3/T4 from TG
  6. T3/T4 secretion out of follicle cell
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12
Q

TG (thyroglobulin) is synthesized in ….and secreted to…

A
  • follicle cell

- secreted to colloid

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13
Q

NIS stands for

A

sodium-iodide symporter (active transport)

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14
Q

Thyroid follicular cells (also called…)

A

thyroid epithelial cells or thyrocytes

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15
Q

thyroglobulin (TG)–def.

A

glycoprotein that contains tyrosine

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16
Q

iodination of tyrosine form..

A

iodotyrosines (MIT & DIT)

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17
Q

Tyr + 1 iodine =

A

MIT

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18
Q

Tyr + 2 iodine=

A

DIT

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19
Q

MIT stands for

A

-Monoiodotyrosine

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20
Q

DIT stands for

A

–Di-iodotyrosine

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21
Q

DIT + MIT=

A

tri-iodothyronine (T3)

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22
Q

DIT + DIT=

A

`tetra-iodothyronine/thyroxine (T4)

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23
Q

T3 stands for…(1 name)

Study These Flashcards
A

tri-iodothyronine

24
Q

T4 stands for.. (2 names)

Study These Flashcards
A
  • tetra-iodothyronine

- thyroxine

25
T4 storage __ T3 storage in colloid
> (greater)
26
T4 secretion __ T3 secretion in blood
> (greater)
27
during thyroid hormones synthesis, there is recycling of ...
I- and amino acids
28
T3 & T4 are transported in blood mainly bound to...
thyroid binding protein (TBP)
29
T3 amount free in blood (%)
0.3%
30
T4 amount free in blood (%)
0.03%
31
which is more potent (T3/T4)?
T3 is 3-8x more potent than T4
32
which is prohormone/biologically active form (T3 & T4)?
prohormone: T4 | biologically active form: T3
33
... is converted to ... in
- T4 - T3 - peripheral cells and liver
34
which is produced more %(T4 OR T3)
T4 (90%) vs T3 (10%)
35
T3 binds to ..
nuclear receptors
36
control of thyroid hormone secretion
↑ TRH secrection ↑ TSH secerection ↑ T3/T4 secrection
37
↑ T3/T4 (feedback)
(-) TSH secretion | (-) TRH secretion
38
↑ T3/T4 (feedback)
(-) TSH secretion | (-) TRH secretion
39
physiological actions of T3/T4
- act on most tissues (change in transcription and translation process) - increase metabolism - required for growth and development
40
7 metabolic effects of T3
1. Catabolism/anabolism ↑ 2. ↑ BMR (basal metabolic rate), ↑O2 consumption ↑heat 3. ↑ carbohydrate absorption/use 4. ↑ protein breakdown (muscle) 5. ↑ fat breakdown 6. ↑ cholesterol metabolism 7. ↑ serum cholesterol (LDL)
41
5 growth + development effects of T3
1. Act as “tissue growth factors” 2. Small amounts stimulate protein synthesis 3. Increase GH/IGF-1 production 4. Essential for CNS maturation during fetal stage 5. Maternal hypothyroidism results in poor fetal CNS development and mental developmental disability
42
3 permissive effects of T3
1. Cardiovascular system (beta adrenergic receptors): increased HR and contractility, increased blood pressure 2. Potentiation of Sympathetic Nervous System (beta-2 adrenergic receptors) 3. Reproductive system: necessary for normal function and fertility
43
graves' disease def. + problem
- is the over activity of gland - autoimmune disorder - antibody to TSH receptor stimulates thyroid hormone production
44
graves' disease associated with
- increased BMR (basal metabolic rate) - exophthalmos (bulging or protruding eyeballs) - goitre
45
hashimoto's thyroiditis def. + problem
- is the underactivity of gland - autoimmune disorder - TPO (thyroid peroxidase) antibody destroy thyroid gland to block hormone synthesis
46
hashimoto's thyroiditis is the most common
autoimmune cause of hypothyroidism
47
hashimoto's thyroiditis associated with
- myxedema (adult-onset) = severely advanced hypothyroidism, swollen puffy skin - goitre - cretinism (in children only)= underactive thyroid function at birth
48
11 hypothyroidism symptoms
1. Lethargy 2. Weight gain 3. Cold intolerance 4. Constipation 5. Nausea / low appetite 6. Menorrhagia (heavy periods) 7. edema 8. Shortness of breath 9. “myxedema madness” 10. Dry skin 11. Brittle hair and nails
49
goitre can happen for both ... cases
hypothyroid and hyperthyroid
50
goitre formation (hyperthyroidism)
``` thyroid gland enlarges ↑ T3/T4 strong negative feedback ↓ TSH ↓ TRH ```
51
goitre formation (hypothyroidism)
``` ↓ T3/T4 (+) ↑TRH, ↑TSH thyroid gland enlarges no iodine T3/T4 remain low ```
52
TSH measurement is the ..... for thyroid function
best single screening test
53
Changes in TSH occur often before measurable changes
in T4 or T3 are present
54
TSH reflects the true state
of Free T4, Free T3
55
Iodine deficiency in the diet is the most common cause of
– Hypothyroidism – Goitre – Developmental/intellectual disability – Preventable brain damage
56
µg iodine/day only needed?
150 µg iodine/day

z:Physl 210A/B (28 decks)

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