Thyroid

Question 1

What makes up mono-iodotyrosine

Answer 1

Tyrosine with one iodine

Question 2

What is the proper name for T3

Answer 2

Liothyronine

Question 3

What is the proper name for T4

Answer 3

Levothyroxine

Question 4

Describe the dimensions of the thyroid gland

Answer 4

2cm thick and 4cm long

Right lobe is usually larger

Question 5

Which gland has the highest blood supply per g in the body

Answer 5

Thyroid

Question 6

Are the thyroid or parathyroid glands more anterior

Answer 6

Thyroid

Question 7

What is meant by thyroid follicle

Answer 7

Lots of thyroidal epithelium surrounding each colloid

Question 8

Describe the epithelium of the thyroid follicles

Answer 8

Cuboidal when inactive

Columnar when active

Question 9

How many follicles are there per lobule

Answer 9

20-40

Question 10

How many arteries are there per lobule

Answer 10

1

Question 11

VERY briefly state how thyroid works to release thyroid hormones

Answer 11

Traps iodine and attaches it to protein
Protein can then be broken down
Hormones can then be released

Question 12

What receptor receives signals from the pituitary gland

Answer 12

TSH receptor

Question 13

What protein is used to oxidise the iodide int he thyroid

Answer 13

Thyroid peroxidase (TPO)

Question 14

What is the oxidising agent for iodide in the thyroid? How is it formed

Answer 14

Hydrogen peroxidase

DUOX1 and DUOX2

Question 15

What travels into the thyroid follicular cell via NIS

Answer 15

2 sodiums and an iodide

Question 16

What is NIS

Answer 16

Sodium iodide sympoter

Question 17

What transports iodide from the thyroid follicular cell to the colloid

Answer 17

pendrin PDS

Question 18

What is the role of ER and golgi body in the thyroid follicular cell

Answer 18

Gives thyroglobulin

Question 19

What is used to recycle iodide

Answer 19

Iodotyrosine dehalogenase 1

Question 20

What % of the thyroid hormones produced are T4

Answer 20

80-90%

Question 21

What is the role of cAMP in controlling thyroid follicular cells

Answer 21

Regulates NIS and moves it to the membrane
Upregulates di-iodinase 2 production which converts T4-T3
Upregulates thyroglobulin
Upregulates oxidising agents
Upregulates digestion of thryoglobulin

Question 22

What molecule must be removed to convert T4 to T3

Answer 22

Iodide

Question 23

What family of enzymes removes iodides from T4

Answer 23

Deiodinases

Question 24

Which specific deiodinases convert T4 into T3

Answer 24

D1 and D2

Question 25

What does D3 do

Answer 25

Converts T4 into the inactive reverse T3

Question 26

Where is D1 most expressed

Answer 26

Liver, kidney and muscle

Question 27

Where is D2 most expressed

Answer 27

Brain and pituitary

Question 28

In what condition is D2 upregulated and why

Answer 28

Hypothyroidism | T4 levels will fall, but D2 is upregulated so that the T4 that is produced in all converted into T3

Question 29

How is thyroid function regulated

Answer 29

- Inverse relationship between iodine levels in the thyroid and rate of hormone formation

Question 30

What is released from the hypothalamus to stimualte pituitary to secrete TSH

Answer 30

TRH

Question 31

How are T4 and T3 transported through the body

Answer 31

Via thyroid binding globulin

Question 32

What kind of receptor is the thyroid hormone receptor

Answer 32

Nucleus receptor

Question 33

Describe the structure of the thyroid hormone receptor

Answer 33

- 2 TRs stuck together with a corepressor stuck to it

Question 34

What happens when T3 binds to one of the receptor units

Answer 34

Corepressor leaves Dimer breaks up Attracts co-activator This activates transcription

Question 35

In general, what is effect of thyroid hormones on the body

Answer 35

Increases basal metabolic rate

Question 36

Define hyperthyroidism

Answer 36

Over active thyroid

Question 37

Define thyrotoxicosis

Answer 37

State of having too much thyroid hormone

Question 38

What are the effects on the cardiovascular system when the person has hyperthyroidism

Answer 38

Increased metabolic rate, so produces heat To get rid of heat, more blood goes to the skin HR and CO increased Prone to AF

Question 39

What metabolic changes can be expected in somebody with hyperthyroidism

Answer 39

- Increased appetite - Heat intolerance - Protein and lipid degradation - Weight loss and myopathy - Accelerated insulin turnover - Hyperglycaemia

Question 40

Why is T1D and hyperthyroidism linked

Answer 40

Both autoimmune

Question 41

What is the effect of hyperthyroidism on the nervous system

Answer 41

Anxious, cross | Increases threshold of seizures

Question 42

Why does Graves disease lead to

Answer 42

Autoimmune process affecting thyroid gland affects the eyes and causes cytokine release at back of the eyes

Question 43

Name 2 signs of hyperthyroidism that can be seen on the skin

Answer 43

Plummer nails | Pretibial myxoedema

Question 44

What is the effect of hyperthyroidism on the GI tract

Answer 44

Weight loss Increased motility Increased appetite Transaminitis

Question 45

What is transaminitis

Answer 45

Damage to liver leading to elevated liver enzymes

Question 46

What is the effect of hyperthyroidism on bones

Answer 46

Accelerated osteoclast activity Hypercalcaemia Osteroporosis

Question 47

What are the effects of hyperthyroidism on haematological system

Answer 47

Pernicious anaemia | B12 deficiency

Question 48

What are the effect of hyperthyroidism on the reproductive system

Answer 48

Oligomenorrhoea Gynecomastia Erective dysfunction

Question 49

What is glynecomastia

Answer 49

Breakdown of testosterone

Question 50

Define Grave's disease

Answer 50

Autoimmune condition leading to invasion of thyroid gland by B and T cells

Question 51

How do the antibodies against TSH receptor act during Graves disease

Answer 51

Act in same way as TSH so stimulate an overexpression in normal function of the thyroid

Question 52

What proteins do antibodies target in Graves disease

Answer 52

TSH receptor Thyroid peroxidase Thyroglobulin

Question 53

Name 4 risk factors for Grave's disease

Answer 53

- HLA status - Infection - Stress - Female sex

Question 54

Why do pregnant women often have thyrotoxicosis

Answer 54

Hcg acts on the TSH receptor- transcient thyrotoxicosis

Question 55

What are the key hormone level differences in hyperthyroidism

Answer 55

Elevated T4 and T3 | Suppressed TSH

Question 56

What thionamide drugs are most commonly used to manage hyperthyroidism

Answer 56

Propylthiouracil | Carbimazole

Question 57

What changes to the skin happen in hypothyroidism

Answer 57

- Put on weight - Skin dries out - Hair dries - Lose outer third of eyebrow

Question 58

What cardiovascular changes in a person with hypothyroidism

Answer 58

Sinus bradycardia | J waves of hypothermia

Question 59

Is there more or less LDL cholesterol in hypothyroidism

Answer 59

More

Question 60

What changes occur in the GI tract in people with hypothyroidism

Answer 60

Reduced appetite | Constipation

Question 61

Are reflexes slow or hyper in hypothyroidism

Answer 61

Slow

Question 62

What changes occur in the renal system in hypothyroidism

Answer 62

Reduced GFR | Mild hyponatraemia

Question 63

What haematological changes occur in hypothyroidism

Answer 63

Normochromic normocytic anaemia

Question 64

Is GLUT4 stimulated decreased or increased in hypothyroidism

Answer 64

Decreased

Question 65

What endocrine changes occur in hypothyroidism

Answer 65

Delayed puberty, reduced libido, erectile dysfunction

Question 66

What characterises Hashimotos disease

Answer 66

Antibodies against thyroid oxidase

Question 67

What is endemic goitre

Answer 67

Not making enough thyroid hormone so the pituitary releases more TSH stimulating it to grow