L74: Thyroid & HPT Axis Flashcards Preview

FHB - Endocrinology (by Richie) > L74: Thyroid & HPT Axis > Flashcards

Flashcards in L74: Thyroid & HPT Axis Deck (56)
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1

Anterior to cricoid cartilage

Location of thyroid gland

2

Two symmetrical lobes fused by

isthmus

3

blood supply by

sup and inf thyroid artery....forms a plexus

4

C-cells produce

calcitonin

5

2 precursors of thyroid hormone

1. Iodide 2. Thyroglobulin

6

Very high doses of Iodide will

rapidly shut down thyroid hormone production in hyperhroid patients

7

Thyroid perixidase TPO

oxidizes iodide to iodine...

8

What inhibits TPO?

Carbimazole (among other drugs)....so you can't oxidize I2 into I-...ultimately cant make thyroid hormone

9

DIT + DIT =

T4

10

MIT + DIT =

T3

11

Megalin

Endocytoses the TG-T3/4 complex from the colloid into the follicular cell.

12

Each step is under TSH control

?

13

What's NIS?

Sodium iodide symporter

14

Diagnostic thyroid gland tests

?

15

>60% uptake

?

16

Graves disease

Antibodies stimulate TSH receptor

Elevated T4/T3

Goiter (symmetrical)

Tachycardia, opthalmopathy, irritability, hyperactivity, heat intolerance, weight loss, nervousness, muscle wasting.

17

Organification defect

I- cannot be added to thyroglobulin in colloid.

18

Predominant in liver

Type I de-iodinase

19

Type II

?

20

Type III

?

21

Type IIi

Inner ring deiodinase (makes reverse T3)

22

Type II

mainly in brain and pituitary (this is the T3 being sensed by pit thyrotropes that is the negative feedback signal)....also in placenta

23

Which has highest affinity for T4?

TBG

24

Upon TSH stimulation, follicular cells (surrounding colloid) turn from

squamous to cuboidal

25

Inactivated follicles have flattened _____ epithelium

squamous

26

Parafollicular cells (C-cells) secrete

Calcitonin

27

5 cell types thyroid gland

Epithelial Fibroblasts Lymphocytes Adipocytes C-cells

28

Parafollicular cells dont touch

colloid

29

2 precursors for TH

Iodide

Thyroglobulin

30

Less than 20micrograms per day of Iodine

Iodine deficiency