Brainscape's Knowledge GenomeTM

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


See full index

Endo/Repro: Week 1 > Rose: Thyroid Physiology and Pharmacology > Flashcards

Rose: Thyroid Physiology and Pharmacology Flashcards

1
Q

Describe the hierarchy of control that regulates the secretion of thyroid hormone.

A

TRH>
TSH>
T3/T4

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

What inhibits TSH release?

A

Somatostatin, DA and high glucocorticoids (adrenal cortex)

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

Describe the structure of TRH.

A

TRH is synthesized as a PREprohormone>

processed to mature protein= TRIPEPTIDE

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

What is the function of TRH?

A

STIMULATES the release of TSH from THYROTROPHS from the anterior pituitary

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

What does TSH regulate?

A

energy homeostasis
feeding behavior
thermogenesis
autonomic regulation

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

How does TRH signaling lead to the release of TSH?

A

TRH binds to transmembrane TRH on thyrotrophs>
TRH coupled to PLC>
IP3>
increased Ca>
release of TSH containing secretory vesicles/synthesis of TSH

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

Describe the structure of TSH. What part of the structure of TSH gives it it’s specificity?

A

Glycoprotein consisting of alpha and beta chains

alpha chains= same found in other pituitary hormones

beta chains= confer specificity of hormonal action of TSH

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

Where are the receptors for TSH located?

A

thyroid follicular cells

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

How does TSH signaling lead to the release of TH?

A

TSH binds TSHR (GPCR)>
activates adenylate cyclase>
increases cAMP>
stimulates TH release and synthesis

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

How does the production of new thyroid hormone affect the regulation of the components needed to make thyroid hormone?

A
  1. upregulates thyroid peroxidase synthesis
  2. thyroglobulin transcription
  3. Na/I transport activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are the 7 steps required to synthesize thyroid hormone?

A
  1. Iodine is transferred into the follicular cell>
  2. iodine is oxidized to iodide
  3. Iodination of tyrosines attached to thyroglobulin protein backbone> MonoIT, DiioIT
  4. Conjugation of MIT and DIT> T3/T4
  5. Endocytosis of T3 and T4
  6. Proteolysis of conjugates into mature T3 and T4
  7. Secretion of T3 and T4 out of cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the two steps in thyroid hormone synthesis that require thyroid peroxidase?

A
  1. Oxidation iof iodide to iodine

4. Conjugation of MIT and DIT to form T3 and T4

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

What is a common drug target to inhibit TH synthesis?

A

Thyroid peroxidase

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

What is the diff between T3 and T4?

A

T2 is more active and has a shorter half life (1 day compared to 6 days)

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

The majority of T3/T4 is bound to…

A

Thyroxin binding protein

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

How does Free T3/T4 enter the cell?

A

diffusion/carrier mediated transport

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

What happens once T3/T4 enter the cell?

A

T3/T4 bind TRH>
homodimerize w/ another T3: TRH>
Homodimers bind TREs>
initiates transcription of thyroid responsive genes

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

What happen to thyroid carrier proteins during pregnancy (or an estrogen/androgen treatment)?

A

INCREASE

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

How do hyperthyroidism, malnutrition and nephritic syndrome affect thyroid carrier proteins?

A

All of these diseases cause PROTEIN LOSS>

and therefore lead to a DECREASE in carrier proteins

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

Bindings sites of TBG?

A

1 binding stie for 1 TH

binds 75% T4
Binds 75% T3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Binding sites of Transthyretin?

A

2 binding sites for TH

binds 20% T4
binds 5% T3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Binding sites for albumin?

A

SEVERAL binding sites for TH

binds 5% of T4
binds 20% of T3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is important for the activation and deactivation of TH?

A

Deiodinases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

DI and II activate?

A

T4 to T3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

DI and DIII deactivate?

A

T4 to rT3

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Where is DI prevalent?

A

liver and kideny

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the role of DI?

A

Can convert T4 to active OR inactive form

T4 > T3 (increases T3 in circulation)

T4> rT3 (disposal)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What is the drug target for Prophylthiouracil?

A

DI

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Where is DII found?

A

brain
pituitary
skeletal and cardiac muscles

30
Q

What is the role of DII?

A

convert T4 to supply INTRACELLULAR T3

31
Q

Where is DIII found?

A

brain
skin
placenta

32
Q

What is the role of DIII?

A

DEACTIVATES hormones

33
Q

What is TH necessary for and what does it promote?

A

Necessary: normal metabolism, growth, development

Promotes: O2 consumption, heat production, free radical formation

34
Q

What are the main functions of TH?

A

regulation of BMR
increased heat production
increased glucose utilization
permissive sympathetic effects (increase HR and contractility)

35
Q

How does congential lack of TH or maternal hypothyroidism affect infants?

A 
mental retardation
short statue
delayed motor development
coarse hair
protuberant abdomen
36
Q

What causes hypothyroidism in infants?

A
  1. Lack of iodine in maternal diet (rare)
  2. Mother w/ Hashimoto’s thyroiditis> blocks anti-TSH receptor Ab
  3. Exposure to radioactive iodine/antithyroid drugs in pregnancy
37
Q

A newborn presents w/ resp. difficulty, cyanosis, jaundice, poor feeding, retarded bone maturation and shorter than expected lengths of the proximal tibial epiphysis.

Dx?

A

Hypothyroidism

38
Q

How do you dx hypothyroidism in an infant?

A

TSH/T4 screening is mandated in most states

*if hormone replacement is started w/in a few days birth growth/development will be normal, if not mental development will not progress but physical can

39
Q

What sxs are associated w/ hypothyroidism in adults?

A 
Insidious onset:
lethargy
slowed intellectual funciton
stiff/aching muscles
cold intolerance
delayed deep tendon reflex
anovulation/amenorrhea
40
Q

What causes primary hypothyroidism?

A

Problems w/ the THYROID GLAND

  1. congential defects
  2. gland destruction (surgical, radioactive, external radiation)
  3. Iodine def
  4. Autoimmune- Hashimotos
41
Q

What is Hashimoto thyroiditis?

A

Chronic lymphocytic thyroiditis >

immune mediated gland destruction

42
Q

What are causes of HYPERthyroidism?

A
  1. Graves disease
  2. thyrotoxicosis
  3. thyroid storm
43
Q

What is Grave’s disease?

A

Excess TSH that you can’t shut off

44
Q

What causes Grave’s disease?

A

T cells become sensitive to thyroid Ag>
stimulate B cells>
B cells produce Abs that mimic TSH>
hyperstimulate TH production

(TSI= thyroid stimulating IGs)

45
Q

How does Grave’s disease affect a fetus?

A 
High TSI  (IgG) can cross the placental membrane>
neonatal hyperthyroidism
46
Q

What is thyrotoxicosis?

A

any cause of EXCESSIVE TH concentration and its effect on organ systems

47
Q

What is a thyroid storm?

A

EXTREME CASE of thyrotoxicosis= medical emergency

48
Q

How do you tx a thyroid storm?

A

B adrenergic blockers
Thioamides (antithyroid)
corticosteroids

49
Q

What are some of the physiological effects of HYPERthyroidism?

A

HYPERcatabolic

Increased protein turnover> loss in skeletal muscle w/ myopathy

Muscle weakness
muscle degeneration
muscle fatigue
heat intolerance

50
Q

What is a goiter?

A

enlarged thyroid gland

51
Q

How does hypothyroidism cause a goiter?

A 
Decreased IODINE in diet>
low T3/T4 synthesis>
signals Hypothal to make more TRH>
more TSH>
stimulates thyroid gland to produce thyroperoxidase, thyroglobulin, increase iodine uptake, increased growth of follicular cells>
BUT no T3/T4 available w/ out iodine>
NOT negative feedback>
GOITER
52
Q

How can hyperthyroidism cause a goiter?

A

lots of circulating T3/T4>
NFB shuts down hormone axis >
BUT increased stimulation of thyroid form Igs in circulation

53
Q

What’s the FIRST test that is ultra sensitive to test for thyroid disorder?

A

TSH= most accurate measure of thyroid activity

Low= HYPER
High= HYPO
54
Q

What do high T3/T4 levels indicate?

A

HYPERthyroidism

55
Q

What is a TSI test?

A

Measures TSI in blood

**ppl w/ Grave’s disease will have this

56
Q

Low TSH

High T4

A

Hyperthyroidism

57
Q

High TSH

Low T4

A

Primary hypothyroidism

58
Q

Low TSH

Low T4

A

Secondary hypothyroidism

59
Q

What drugs are used to tx hypothyroidism?

A

Levothyroxine (T4)

Liothyroinine (T3)

60
Q

Which drug used to treat HYPOthyroidism has a great potency and quicker onset?

A

T3

61
Q

What drugs are used to tx HYPERthyroidism and prep the thyroid for surgery?

A
  1. Methimazole/Carbimazole
  2. Proprylthiouracil
  3. K Iodine
62
Q

What is hte MOA of Methimazole/Carbimzole and Proprylthiouracil?

A

Inhibit thyroid peroxidase>
affects:
oxidation of iodide
conjugation rxns producing T3/T4

Proprylthiouracil also inhibits DI> inhibits conversion of T4 to T3

63
Q

What is hte MOA of K Iodine?

A

High drug concentration INHIBITS iodine metabolism

64
Q

What is the first line treatment for Graves?

A

Methimazoles and Carbimazole

*lasts 24hrs, takes 2 wks to have effect

65
Q

What is a second line treatment for Graves and a first line tx for hyperthyroidism seen in pregnant women?

A

Proprylthiouracil

66
Q

Hepatoxicity is assoc with what tx for hyperthyroidism?

A

Proprylthiouracil

*this is why it’s second line for Graves

67
Q

Allergic rxns, sore teeth, gums, and excess salivation are all associated with what tx for hyperthyroidism?

A

K Iodine

68
Q

What is the TU of K Iodine?

A

Prep for thyroid surgery
tx thyroid storm
protect from radioactive Iodine

69
Q

What is I-123 used for?

A

scan thyroid (imaging)

70
Q

What is I-131 used for? What is the main disadvantage of using I-131?

A 
destroy thyroid (ablation)
too much destruction

Endo/Repro: Week 1 (10 decks)

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