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Flashcards in Thyroid Physiology Deck (40)
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1
Q

At what vertebral level is the thyrod gland found?

A

C5 - T1

2
Q

What supplies parasympathetic control to the thyroid gland?

A

Vagus nervee

3
Q

What is the arterial supply for the thyroid?

A

Superior and inferior branches of the thyroid arteries

( branch of the external carotid artery )

4
Q

What is this stucture called?

A

A Follicle

5
Q

What are the cells making up the ring called?

A

Follicular cells

6
Q

What is the middle of the ring called and what does it contain?

A

Collioid thyroglobulin

7
Q

What ingredient is required to make thyroid hormones?

A

Iodine

8
Q

Two DITs makes ….

A

T4

9
Q

One MIT and One DIT makes ____?

A

T3

10
Q

What percentage of thyroid hormone is thyroxine and what percentage is triiodothyronine ?

A

90% thyroxine T4

10% Triiodothyronine T3

11
Q

What thyroid hormone is more potent T3 or T4?

A

T3 is 4x more potent

12
Q

What plasma proteins do T3 and T4 bind to?

A

Thyroxine binding globulin 70%

Thyroxing binding prealbumin 20%

Albumin 5%

13
Q

What effects do thyroid hormones have on metabolic rate and thermogenesis?

A

Increase metabolic rate

Increases thermogenesis

14
Q

What effect do thyroid hormones have on sympathetic action?

A

Increases responsiveness to adrenaline and sympathetic neurotransmitters.

15
Q

What stimulates the thyroid and where does it come from ?

A

Thyroid stimulating hormone from the anterior pituritory gland

16
Q

What is graves disease?

A

Autoimmune disease where Thyroid stimulating immunoglobin acts like thyroid stimulating hormone leading to hyperthyroidsism

17
Q

What 3 hormones does thyroid gland tissue secrete?

A

Thyroxine (T4)

Tri-iodothyronine (T3)

Calcitonin

18
Q

What do the parathyroid glands secrete?

A

Parathyroid Hormone PTH

19
Q

What veins drain the thyroid gland?

A

Superior and middle thyoid vein into the internal jugular vein

Inferior thyroid vein into the brachiocephalic vein

20
Q

How are thyroid hormones regulated?

A

Thyrotrophin releasing hormone (TRH) from the hypothalmus stimulates the anterior pituitary to release thyroid stimulating hormone. (TSH)

21
Q

What a patient with an over active thyroid what would be the TSH T4 and T3 levels?

A

T4/T3 high

TSH low

22
Q

What would be the TSH T3 and T4 levels in a failing thyroid gland?

A

TSH high

T4/T3 low

23
Q

What would the TSH and T3/T4 values be in secondary hyperthyroidism?

A

TSH high

T3/T4 high

24
Q

What does Myxoedema mean?

A

Severe hypothyroidism

or

Skin disease associated with Graves

25
Q

What is Hashimoto’s hyroiditis?

A

Autoimmune hypothyroidism

26
Q

What happens in autoimmune hypothyroidisim?

A

Autoimmune destruction of the thyroid gland resulting in reduced thyroid hormone production

27
Q

What is characterisitic of Hashimoto’s thyroiditis?

A

Presence of Thyroid Peroxidase antibodies

T-cell infiltrate and inflammation on microscopy

28
Q

What are the facial signs and symptoms of hypothyroidisim?

A

Coarse, sparse hair

Periorbital puffiness

Loss of outer eyebrows

Peri-orbital puffiness

29
Q

What is the management plan for hypothyroidisim?

A

In young patients:- 50-100micrograms

In elderly with ischeamic heart disease:- start at 25-50 micrograms

30
Q

What happens in Myxoedema coma?

A

extreme hypothyroidisim

Type 2 respiratory failure

Bradycardia, low voltage complexes, heart block, prolonged QT interval

31
Q

What happens to the menstral cycle in patients with

(a) hyperthyroidisim
(b) Hypothyroidisim

A

Hyperthyroidisim - Less frequent and lighter bleeding

Hypothyroidisim - Heavier bleeds

32
Q

What are the three common causes of hyper-thyroidism?

A

Graves disease

Nodular thyroid

Thyroiditis

33
Q

What is the natural progression of graves disease?

A

after 18 months 50% will “burn out”

50% will relapse

34
Q

What is responsible for graves disease

A

Thyroid stimulaing immunoglobulin

35
Q

What is Thyroid storm?

A

Severe hyperthyroidisim resulting in respiratory and cardiac collapse

36
Q

How do you treat hyperthyroidism?

A

Carbimazole

37
Q

How do you treat hyperthyroidism in pegnancy?

A

Propylthiouracil

38
Q

What is De Quervains Thyroiditis?

A

Sub-Acute Thyroiditis

39
Q

What happens in sub-Acute thyroiditis?

A

T4 is high in early stage , low in late then is normal

TSH componsates accordanly

Can be triggered by viral infection ( Sore throat etc)

40
Q
A