Thyroid physiology and anatomy 1 (read) Flashcards Preview

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Flashcards in Thyroid physiology and anatomy 1 (read) Deck (19)
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1
Q

What is the innervation of the thyroid gland ?

A
  • Parasympathetic from vagus nerve
  • Sympathetic from superior middle and inferior ganglia of sympathetic trunk
2
Q

Describe the blood supply of the thyroid gland

A

Superior and inferior thryoid arteries +/- thyroida ima

3
Q

Describe the venous drainage of the thyroid gland

A

3 pairs of veins - superior/middle thyroid vein ==> internal jugular

inferior thyroid vein ==> brachiocephalic vein

4
Q

What is the thyroid gland supported by ?

A

Ligaments and strap muscles

5
Q

What is the main ligament which supports the thyroid gland ?

A

The posterior suspensory ligament (berry ligament)

6
Q

What is there a risk of injuring during surgery on the thyroid ?

A
  • Injury to the vasculature
  • Injury to the recurrent laryngeal nerve
7
Q

What are the 3 primary features of thyroid glands under the microscope ?

A
  1. Follicles
  2. Follicular cells
  3. Parafollicular cells
8
Q

What are follicles in the thyroid ?

A

Small spherical groupings of cells that consist of a rim of follicular cells which surround the colloid

9
Q

What are parafollicular cells ?

A

Scattered amoung follicular cells and the spaces between follicles

10
Q

What is the colloid ?

A

Tyrosine containing thyroglobulin filled spheres enclosed by follicular cells

11
Q

What do follicles play a key role in ?

A

Thyroid function

12
Q

What is the function of follicular cells ?

A
  1. When stimulated by TSH
  2. Secrete thyroid hormones T3 and T4
13
Q

What is the function of parafollicular cells ?

A

Secrete calcitonin

14
Q

What is the overall idea of synthesis and secretion in the thyroid gland ?

A

Iodine (the fuel) comes in and then T3/T4 (products) come out

15
Q

Describe the stages of synthesis of T3 & T4

A
  1. Iodine taken up by follicular cells
  2. Iodine attaches to tyrosine residues on thyroglobulin to form MIT and DIT
  3. MIT = monoiodotyrosine unit, DIT - Diiodotyrosine unit
  4. Coupling of MIT and DIT = T3 (triiodotyrosine unit)
  5. Coupling of 2 DIT’s = T4 (thyroxine)
  6. T3 and T4 are then stored in colloid till required
16
Q

What is the major biologically acitve thyroid hormone ?

A

T3 - it is roughly 4 times more potnet but 90% of thyroid hormones secreted is T4

17
Q

Where is T4 converted to T3 ?

A

Converted in the liver and kidney

18
Q

What is the function of Deiodinase enzymes ?

A

To either activate or deactivate thyroid hormones

There is 3 types:

  • D1
  • D2
  • D3
19
Q

Which Deiodinase enzyme converts T4 into T3 ?

A

D2 in the tissues