Physiology Thyroid Book Flashcards

1
Q

How is iodide converted to iodine

A

Thyroid peroxidase

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

Process of making thyroid hormones

A

Iodide is absorbed from plasma by pump
Converted to iodine by TPO
Secreted into colloid where it is added to tyrosine by enzyme iodinate
These bind to protein- thyroglobulin
TSH causes them to be released back into thyroid follicular cell and released by proteolysis

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

Composition of thyroid hormones in blood

A

99% bound to TBP and albumin
T4 higher conc

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

Effects of thyroid hormones on body

A

Increase isotropic effect on heart
Increase protein breakdown
Increase carb absorption
Lipolysis

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

3 hormones produced by thyroid

A

Tetra- principle hormone
Tri- shorter duration but more potent
Calcitonin- parafollicullar C cells

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

Where does PTH act

A

Bone- resorption
DCT- reabsorption of Ca
PCT- excretion of PO4
Vit D formation

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

Overall net effect of hyperparathyroidism on Ca exrection

A

Net excreten despite absorption in DCT due to overwhelmed

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

Effect of thyroid hormone on PVR

A

Decrease due to raise in temp

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

Effect of thyroid hormones on cholesterol

A

Increase LDL receptors- increased removal of cholesterol from circulation

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

Where are thyroid receptors found

A

Intranuclear hormones
Which bind to DNA via zinc fingers

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

Types of thyroid receptors

A

TRB2- brain
TRa2, TRB1- widely distributed in Body
T3 unable to bind to a2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Factors inhibiting osteoclasts

A

Calcitonin, oestrogen, PGE2

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

What inhibits osteoblasts

A

Corticosteroids

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

How PTH causes action in cells

A

Binds to surface receptors
Increase cAMP

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

What cell is PTH released from

A

Chief cells

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

Biochemistry of primary HPTH

A

High PTH
High Ca
Low PO4
Normal VitD
Raised urinary Ca

17
Q

Biochemistry of secondary HPTH

A

Low Ca
High PTH
High PO4

Causes- renal failure and vid D def

Renal failure- high phosphate which inhibits Vid d synthesis
Or Failure of 1a production

18
Q

Biochemistry of tertiary HPTH

A

High Ca
High PTH
High PO3- due to original renal failure
Developed after longstanding secondary HPTH

19
Q

Effects of calcitonin

A

Decrease bone resorption
Increase renal exretion of Ca and PO4

20
Q

Factors increasing calcitonin secretion

A

B adrenergic agonists
Glucagon
Gastrin
CCK
Oestrogens

High Ca

21
Q

Sx of hypocalcaemia

A

Tetany
Numbness
Prolonged QT

Chvostek- contraction of facial muscle when tapping on angle of jaw

Trousseau- wrist flexion and fingers drawn together in extension when BP cuff inflated

22
Q

Why does low Ca cause tetany

A

Low Ca increases neuronal permeability

23
Q

Hypercalcaemia sx

A

Constipation
Increases uriantion

Bone pain
Abdo pain
Mental health
Renal stones

24
Q

Causes of high Ca

A

Primary HPTH
Malignancy- breast, lung, SCC
Multiple myeloma
Renal failure
Thiazide use

25
Q

Effect of surgery or trauma on thyroid hormones

A

Decrease for a few days

26
Q

Sick euthyroid syndrome biochemistry

A

Low T3
Normal T4 and TSH- may be high

27
Q

Medications that effect levothyroixine absorption

A

Iron
Ca
PPI
Statins
Oestrogens

28
Q
A