Thyroid Anatomy Flashcards

1
Q

What tethers the thyroid to the trachea

A

pre-tacheal fascia

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2
Q

What is in the pre-tacheal fascia (5)

A
thyroid
recurrent layngeal nerve
oesophagus
trachea
pharynx
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3
Q

What vertebral level is the thyroid at?

A

C5-T1

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4
Q

Where are the parathyroid glands located on the thyroid?

A

posterior aspect

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5
Q

What is the function of parathyroid glands?

A

calcium homeostasis

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6
Q

How many parathyroid glands are there?

A

four

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7
Q

2 main sources of thyroid blood supply

A

superior thyroid artery

inferior thyroid artery

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8
Q

What is the superior thyroid artery a branch of?

A

external carotid artery

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9
Q

What is the inferior thyroid artery a branch of?

A

thyrocervical trunk

from the subclavian artery

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10
Q

Venous drainage of the thyroid occurs through..

A

superior
middle
inferior thyroid veins

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11
Q

Which veins drain to the internal jugular vein?

A

superior

middle thyroid vein

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12
Q

Which vein drains to the brachiocephalic vein

A

inferior thyroid vein

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13
Q

What innervates the thyroid?

A

sympathetic fibres

from superior, middle and inferior cervical ganglia

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14
Q

What travels behind the thyroid to supply laryngeal muscles?

A

recurrent laryngeal nerve

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15
Q
Perithyroid
Pre-laryngeal
Pre-tracheal
Paratracheal
Superior and inferior deep cervical
A

Lymph nodes draining the thyroid

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16
Q

What is the site of hormone production and storage in the thyroid?

A

colloid

17
Q

Function of C cells/parafollicular cells?

A

secrete calcitonin

for calcium homeostasis

18
Q

Thyroid hormones

A

Thyroxine (T4)
Triiodothyronine (T3)
Calcitonin

19
Q

Most abundant thyroid hormone

A

T4

20
Q

Most active thyroid hormone

A

T3

21
Q

Thyroid transport proteins

A

thyroid binding globulin
albumin
transthyretin

22
Q

In response to stimuli, what does the hypothalamus release?

A

thyrotropin-releasing hormone (TRH)

23
Q

In response to TRH, what does the anterior pituitary release?

A

thyroid stimulating hormone (TSH)

24
Q

What does TSH stimulate the production of?

A

T3 and T4

25
Q

What is the negative feedback loop of the thyroid

A

Increase in T3 and T4 results in

reduction in TRH and TSH

26
Q

What happens to T3 and T4 in Hypothyroidism

A

decreases

27
Q

What happens to T3 and T4 in Hyperthyroidism

A

increases

28
Q

What is most plasma T3 derived from?

A

peripheral metabolism of T4

29
Q

What does conversion from T4 to T3 require?

A

removal of iodine by a deiodinase enzyme

30
Q

What can T4 also be metabolised to?

A

reverse T3 (rT3)

31
Q

Thyroid hormone receptors

A

TRa1
TRa2
TRb1
TRb2

32
Q

Which hormone receptor does not bind T3?

A

TRa2

33
Q

What happens when T3 binds to the thyroid hormone receptor

A

gene transcription activated
form mRNA
followed by a translation to a protein

34
Q

Function of thyroid hormones in metabolism

A
increase in basal metabolic rate
glycolysis
O2 consumption
thermogenesis
protein turnover
35
Q

Function of thyroid hormones in cardiovascular system

A

increase in systolic pressure
increase in B-adrenergic receptor
enhances catecholamine actions