Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Therapeutics > Lecture 37: Thyroid Hormones > Flashcards

Lecture 37: Thyroid Hormones Flashcards

1
Q

Thyoid gland

A

-in the neck

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

Thyroid hormones

A

-Thyroxine (T4) x10
-Triiodothyronine (T3) mor potent

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

Effect of thyroid hormones on growth and development

A

-essential for brain development
-promote protein synthesis (skeletal/muscle)
-anabolic at normal levels but catabolic at high levels

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

Cretinism caused by

A

-absent T3

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

Effects of thyroid hormones on metabolism

A

-increase BMR
-inc oxygen consumption
-starvation lowers T3 and thyroid receptor

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

Starvation lowers levels of

A

-T3 hormone
-thyroid receptors

-to dec BMR to save energy

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

Effect of thyroid hormones on Thermogenesis

A

-inc resting heat production
-inability to adjust to environmental temp is characteristic symptom of hyper/hypo thyroidism

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

Effect of thyroid hormones on cardiovascular system

A

-inc catcholamine sensitivity

  • makes heart beat more
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Biosynthesis of Thyroid hormones

A
  1. Dietary Iodine
  2. NIS transport
  3. Pendrin transport and oxidation by thyroid peroxidase
  4. thyroglobulin transport
  5. Iodide Organification
  6. Coupling
  7. Retrievement
  8. Cleavage
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q
  1. Dietary Iodine (I2)
A

-turned to iodide (I-) in tummy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q
  1. Na+-I- symporter (NIS)
A

-transports iodide into follicular cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q
  1. Pendrin transport and Oxidation
A

-iodide passes down electrochemical gradient into follicular COLLOID w help from PENDRIN transporter
-oxidized to I0 at apical membrane by throid peroxidase

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

Pendrin

A

-apical transport protein
-helps iodide into follicular colloid for oxidation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q
  1. iodide-free throglobulin transported to
A

apical membrane

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

-thyroglobulin iodinated at 1 or 2 positions by thyroid peroxidase
-Monoiodotyrosine and di-iodotyrosine (MIT and DIT)

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

-MIT + DIT = T3
-DIT + DIT = T4

-dependent on thyroid peroxidase

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

-thyroid hormone-containing thyroglobulin is retrieved back into cytosol of follicular cell as colloid droplets by pinocytosis

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

-Lysosomal exopeptidases cleave T4 or T3 from thyroglobulin
=release hormone into circulation where T4 can be converted to more potent T3 by 5’deiodinase

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

thyroid peroxidase

A

-oxidizes iodide
-iodinates thyroglobulin to MIT or DIT
-couples MIT and DIT

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

5’ deiodinase

A

-converts T4 to T3
-happens in circulation

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

Hypothalamus-pituitary-thyroid axis

A

-hypothalamus releases TRH
-stimulates anterior pituitary to relase TSH
-stimulates thyroid to release T3 and T4

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

negative feedback loop

A

-T3 and T4 inhibit hypothalamus and anterior pituitary directly
-which indirectly inhibits thyroid gland

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

TRH

A

thyrotropin releasing hormone

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

TSH

A

thyrotropin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Iodine
-used for synthesis of thyroid hormones -routinely added to table salt
26
best natural food source for iodine
-fish -seaweed
27
Iodine deficiency
-endemic in inland populations -goiter and crentinism
28
goiter
enlargement of thyroid gland due to persistent rise in TSH but no iodine to make hormone
29
crentinism
-severely stunted physical and mental growth
30
Thyroid hormone transport
-Thyroxine-binding globulin (TBR) (primary) -Transthyretin (TTR) -Albumin
31
Primary transport protein of thyroid hormones
TBG
32
transport proteins have a greater affinity to
-T4
33
T4 in the body
-only 0.04% is free -longer half life than T3 but slower onset -serves as a storage pool (2-3 months)
34
Thyroid hormone mech of action
-belong to nuclear receptor family -similar to steroid -bind nuclear and inc transcription
35
Metabolism of Thyoid hormones
-deiodination -conjugation to form glucuronide or sulfate w phenolic group -excreted via bile -some hydrolyzed by bacteria -marginal enterhepatic circulation
36
structures
slide 14
37
HYPOthyroidism
-deficiency of thyroid hormones
38
Symptoms of HYPOthyroidism
-dec metabolism = fatigue, mental dullness, lethargy, inattention -defective thermoreg -may occur w goiter -dwarfism/cretinism in infants and children -Myxoedema coma
39
myxoedema coma
-end state of untreated HYPOthyroidism -water intoxication -shock -death
40
Causes of HYPOthyroidism
-Hashimoto's thyroiditis -destruction/removal of gland (no goiter) -idodine deficiency (goiter) -congenital cretinism -secondary: TSH deficiency
41
Hashimoto's thyroditis
-most common cause of HYPOthyroidism -autoimmune disease that destroys thyroid gland
42
Secondary cause of HYPOthyroidism
-TSH deficiency
43
HYPERthyroidism
-excessive levels of thyroid hormones (thyrotoxicosis)
44
Symptoms of HYPERthyroidsism
-excessive metabolism -poor thermoreg and weight loss -inc HR and cardiac output
45
Causes of HYPERthyroidism
-Graves' disease -Toxic uninodular goiter and toxic multinodular goiter -Subacute thyroiditis
46
Graves' Disease
-most common cause of HYPERthyroidism -autoimmune -thyroid stimulating IgG -toxic goiter
47
Toxic uni/multi nodular goiter
-adenoma producing excess T3 -mostly in older women -causes HYPERthyroidism
48
Subacute Thyroiditis
-viral infection of thyroid gland -transient release of store thyroid hormones -HYPERthyroidism
49
HYPOthyroid skin
-pale -cool -puffy
50
HYPERthyroid skin
-warm -moist -sweaty
51
HYPOthyroid eyes
-droopy eyelids
52
HYPERthyroid eyes
-retraction of upper lids -exophthalmos
53
HYPOthyroidsim CV effects
-BRADYcardia -dec CO -inc vasc resistance
54
HYPERthyroid CV effects
-TACHYcardia -inc CO -dec vasc resistance
55
HYPOthyroid CNS
-lethargy
56
HYPERthyroidism CNS
nervousness
57
HYPOthyroidism metabolism
-dec appetite -dec BMR -hYPOglycemia -inc cholesterol and triglycerides -dec drug metabolism
58
HYPERthyroid metabolism
-inc appetit -inc BMR -HYPERglycemia -dec cholesterol and triglycerides -inc drug metabolism
59
Hypothyroidism treatment
-Thyroid Hormone Replacement Therapy
60
Thyroid Hormone Replacement Therapies
-Natural Thyroid hormone preparations (not FDA approved) -Levothyroxine (T4) -Liothyronine (T3) -Liotrix (disc)
61
Natural Thyroid hormone preparations
-not FDA approved -HYPOthyroidism treatment -dessicated thyroid and thyroglobulin (bovine or porcine) -variable T4/T3 blood levels due to inconsistencies in sources
62
Levothyroxine (T4!)
-HYPOthyroidism treatment -converted to T3 intracellularly -slow onset -long half-life (week) -6-8 weeks to reach steady state levels
63
Liothyronine (T3!)
-HYPOthyroidism treatment -rapid onset -short duration (24h) -need multiple daily doses -greater cardiotoxicity risk -difficult to monitor via lab tests
64
Liotrix (disc)
-4:1 T4 to T3 ratio -more expensive -not more effective than T4 admin alone -discontinued
65
HYPERthyroidism drugs
-Thioamides -131I -Iodide
66
Thioamides
-HYPERthyroidism treatment -antithyroid -treat thyrotoxicosis -inhibit thyroid peroxidase =block iodine organification and coupling -slow onset (3-4 weeks) -require depletion of stored T4
67
Thioamide drugs
-Methimazole -Propylthiouracil
68
131I
-HYPERthyroidism -radioactive iodine -emit B particles and gamma rays -8 day half life -localized destruction of thyroid follicles -admin orally in solution as Na131I
69
problems w 131I
-HYPOthyroidism occurs in 80% of patients -potential inc in some cancer -radiation thyroiditis in rare cases (storm?!) = prevent w pretreatment of antithyroid drugs -radioactive urine
70
131I contraindication
-not for pregnant or breastfeeding
71
131I advantage
-no surgery -lower cost
72
Iodide treatment
-for HYPERthyroidism -lots of I- inhibits own uptake , organification, and release of thyroid hormones -dec vascularity of thyroid gland -not for long term use
73
Lugol's solution
-aq solution of I and KI -iodide treatment for HYPERthyroidism
74
Iodide clinical uses
-prep for thyroidectomy -severe thyrotoxicosis -protection from radioactive iodine fallout (nuclear/military exposure)
75
Iodide side effects
-HYPOthyroidism -sensitivity to idodine in some patitents (angioedema)

Therapeutics (78 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions