Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Physiology Block 8 > Hypothalamic-pituitary-thyoid Axis > Flashcards

Hypothalamic-pituitary-thyoid Axis Flashcards

(62 cards)

Start Studying
1
Q

What is the HPT axis concerned with

A

Production of thyroid hormone (T3 and T4)

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

In the HPT axis what does the hypothalamus release

A

TRH

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

In the HPT axis, what does the anterior pituitary gland release

A

TSH

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

In the HPT axis, what does the thyroid release

A

T4 and T3

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

Thyroxine

A

T4

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

What happens to T4 in target tissues

A

Converted to T3

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

Which is more potent, T3 or T4

A

T3

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

Which is easier to make in the thyroid, T3 or T4

A

T4

That’s why T4 gets released from thyroid and then it gets converted to T3

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

Feedback of the HPT axis

A

Both short and long loop

  • TSH inhibits TRH
  • T3-T4 inhibit TSH and TRH
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the master metabolic hormones

A

T3/T4

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

What are the metabolic functions of T3 and T4

A
  • signals through steroid pathway (but its amine)
  • bone growth and maturation
  • CNS maturation
  • increases BMR and heat production
  • increases all body metabolism
  • increases cardiac output
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

A consequence of hypothyroidism would be

A

Cold intolerance

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

What does the thyroid contain

A

Follicular epithelial cells

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

What do the follicular epithelial cells of the thyroid do

A

Make thyroid hormone

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

Where does the basal membrane of the follicular epithelial cells of the thyroid face

A

Blood

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

Where do the apical membrane of the cells of the follicular epithelium of the thyroid face

A

Colloid

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

Mixture of forming thyroid hormone attached to thyroglobulin

A

Colloid

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

Protein that binds and helps form thyroid hormone

A

Thyroglobulin

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

What does thyroid hormone synthesis require

A

Dietary iodine

-iodized salt and other sources

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

How Is thyroid hormone synthesized

A

By stepwise addition of iodine to tyrosine

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

What thyroid hormones have biological functions

A

T3 and T4 only

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

How are thyroid hormones synthesized

A
  • iodide pumped into the cell from blood (forms iodine when entering the colloid)
  • tyrosine on thyroglobulin are iodinated (iodine is added to tyrosine, makes MIT and DIT)
  • iodinated thyroglobulins combine
  • thyroglobulin with T3, T4, DIT, and MIT stay in colloid
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What are the combinations of iodinated thyroglobulins that make up thyroid hormones

A
  • two DITs make T4
  • one DIT and one MIT make T3
  • remainder of other MIT and DIT remained attached
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What makes MIT and DIT

A

Tyrosine on thyroglobulins are iodinated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
When does iodide turn to iodine?
When entering the colloid
26
How are T3 and T4 secreted into circulation
- upon stimulation thyroglobulin and the attached thyroid hormones is brought into the cell - T3 and T4 are removed from thyroglobulin and secreted into circulation - MIT and DIT on thyroglobulin are deiodinated and recycled to repeat the process
27
What is the average intake of iodine a day
500ug, only need 150
28
What happens to most of the iodine
Taken up by the thyroid to make T3 and T4
29
Degradation of T3 and T4
Liver degrades T3 and T4 and releases iodine back into blood
30
Where is most iodine secreted
By the kidney
31
T3/4 in blood
- not easily dissolved in blood - is carried bound to proteins - albumin and specific thyroxine binding proteins
32
What kind of T3 and T4 can be sensed and regulated
Only free T3 and T4
33
What kind of T3 and T4 can be degraded
Only free T3/T4
34
Yo are researching a new drug and discover it rapidly increases albumins affinity for T3/T4. What affect would this have on TSH levels?
Increase
35
Why kind of steroid is T3/T4
Amine, but acts like a steroid
36
How are T3 and T4 carried
Binding proteins
37
What do T3 and T4 activate
Intracellular receptors
38
What does T3 and T4 do once it binds intracellular receptors
Directly initiates transcriptional changes
39
What converts T4 to T3? | ****
Iodinase in tissues | ****
40
Thyroid hormone action
- primarily a metabolic regulator - causes bone formation and growth - allows for maturation of CNS - increases basal metabolic rate - increases metabolism - increases cardiac output
41
Thyroid hormone and bone growth
- causes bone formation and growth - required for growth to adult stature - act with growth hormones to regulate growth of bones
42
Thyroid hormone and maturation of CNS
- allows for maturation of CNS - required in the prenatal period for full CNS development - in adults altered T3/T4 levels cause central defects
43
How does thyroid hormone increase BMR?
- increase Na/K ATPase - increase O2 consumption (except brain, gonads, and spleen) - increase heat production - increase BMR
44
Thyroid hormone and metabolism
Increases availability and uptake of glucose, proteins, and fats
45
Thyroid hormone and cardiac output
- higher O2 consumption requires more CO to meet demand | - also activates SNS
46
Hyperthyroidism
Too much T3/T4
47
What are some examples of disorders that cause hyperthyroidism
- Graves' disease - thyroid tumor - TSH/TRH secreting tumor
48
What us Graves' disease
Autoimmune disease where Ab activate the receptors on the thyroid causing it to release too much T3/T4
49
What are some symptoms of hyperthyroidism
- weight loss - heath intolerance - sweating - increased cardiac output - exopthalamos - goiter
50
Hypothyroidism
Not enough T3/T4
51
What are some disorders that can cause hypothyroidism
- Hashimotos - iodine deficiency - congenital (cretinism)
52
What is Hashimotos
Destruction of thyroid gland by immune system
53
What are some symptoms of hypothyroidism?
- weight gain - cold intolerance - low cardiac output - mental slowness - lack of energy - myxedema (swollen, puffy, skin)
54
Treatment for hypothyroidism
Give them exogenous T3/T4 or iodine
55
What is the treatment for hyperthyroidism
Remove the thyroid/ tumor
56
Congenital hypothyroidism
- cretinism - due to necessity of T3/T4 for normal development prenatal hypothyroidism causes both physical and metal developmental abnormalities - learning disabilities - growth is inhibited
57
Enlarged thyroid gland
Goiter
58
When can you get a goiter
Can occur in either hyper or hypothyroidism
59
Why is the thyroid enlarged when you have a goiter
High TSH levels
60
What kind of hypothyroidism would you not have a goiter
Hashimotos
61
What kind of hypothyroidism could give you a goiter
Iodine deficiency
62
What kind of hyperthyroidism could give you a goiter
Graves Thyroid tumor TSH/TRH secreting tumor

Physiology Block 8 (7 decks)

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