The thyroid in health and disease

Question 1

What are the follicles in the thyroid filled with

Answer 1

colloid

Question 2

what epithelial is in the thyroid

Answer 2

cuboidal epithelial cells

Question 3

what is special about the thyroid

Answer 3

stores and secretes hormones

Question 4

what do the parafollicular cells produce

Answer 4

Calcitonin

Question 5

what do the follicular cells produce

Answer 5

T3 and T4

Question 6

what controls the release of thyroid hormones

Answer 6

Hypothalamo-pituitary axis

Question 7

HPA for thyroid =

Answer 7

releases TRH from hypothalamus
Anterior pituitary releases TSH
TSH stimulates the thyroid to release T3 and T4
T3 and T4 negative feedback

Question 8

TRH=

Answer 8

thyrotropin releasing hormone

from the hypothalamus

Question 9

TSH=

Answer 9

Thyroid stimulating hormone

released from the anterior pituitary

Question 10

T3=

Answer 10

Triodothyronine

Question 11

T4=

Answer 11

Thyroxin

Question 12

T3 is made up of

Answer 12

2 tyrosine with 3 iodine

Question 13

T4 is made up of

Answer 13

2 tyrosine with 4 iodine

Question 14

overall function of thyroid hormone (3)

Answer 14

increase metabolic rate
positive inotropic and chronotropic
growth and development

Question 15

bc Thyroid hormone increases metabolism and heat production what is it

Answer 15

calorigenic

Question 16

how does thyroid hormone increase growth in children

Answer 16

stimulates GH secretion and promotes GH effects

Question 17

lack of growth hormone=

Answer 17

growth retardation

Question 18

in foetal and postnatal life thyroid hormone deficiency =

Answer 18

mental retardation

Question 19

where does synthesis of thyroid hormone take place

Answer 19

in the follicles on the thyroglobulin molecule

Question 20

what ion is needed in producing thyroid hormone

Answer 20

iodine

Question 21

1st step in thyroid hormone production

Answer 21

iodine atoms are actively transported across follicular cells and trapped in the colloid

Question 22

what happens to iodine in the colloid

Answer 22

it is oxidised to iodine I2 by thyroid peroxidase

Question 23

what enzyme oxidises iodine

Answer 23

thyroid peroxidase

Question 24

what does I2 attach to in the thyroglobulin molecule

Answer 24

tyrosine

Question 25

1 iodine + tyrosine=

Answer 25

MIT (monoiodotyrosine)

Question 26

2 iodine + tyrosine=

Answer 26

DIT (di-iodotyrosine)

Question 27

how do MIT and DIT combine

Answer 27

via thyroid peroxidase enzyme

Question 28

T3 combo=

Answer 28

MIT+ DIT

Question 29

T4 combo=

Answer 29

DIT + DIT

Question 30

what happens to any MIT/DIT that hasn't formed T3/T4

Answer 30

recycled back into process

Question 31

where is all the bodies t4 produced

Answer 31

thyroid gland

Question 32

where is the main source of T3

Answer 32

deiodination of T4 in liver and kidneys

Question 33

Actions of TSH (4)

Answer 33

- causes active uptake of iodine - stimulates other reactions involved in thyroid hormone synthesis - stimulates the uptake of colloid - induces growth of the thyroid

Question 34

majority of T3 and T4 bound to

Answer 34

TBG (thyroid binding globulin)

Question 35

thyroid hormone mechanism of action

Answer 35

bind to transmembrane receptor and directly alter gene expression in cells that regulate metabollic rate

Question 36

3 hypothyroid diseases

Answer 36

primary secondary tertiary

Question 37

2 types of primary hypothyroidism

Answer 37

congenital | acquired

Question 38

congenital hypothyroidism is usually due to

Answer 38

absence of thyroid or ectopic thyroid

Question 39

acquired hypothyroidism is due to (2)

Answer 39

iodine deficiency | autoimmune

Question 40

levels in primary hypothyroidism

Answer 40

High TSH High TRH low T4/T3

Question 41

symptoms of hypothyroidism

Answer 41

fatigue cold intolerance depression Myxedema (retention of water)

Question 42

Hashimoto's disease=

Answer 42

autoimmune thyroiditis

Question 43

most common cause of hypothyroidism=

Answer 43

hashimoto's disease (autoimmune)

Question 44

what is hashimoto's disease associated with

Answer 44

thyroid peroxidase and thyroglobulin antibodies

Question 45

what happens on the thyroglobulin molecule

Answer 45

MIT and DIT are combined to make T3 and T4

Question 46

levels in secondary hypothyroidism

Answer 46

Decreased TSH | Decreased T3/ T4

Question 47

example of a secondary hypothyroidism

Answer 47

pituitary tumour

Question 48

2 main causes of hyperthyroidism

Answer 48

autoimmune | toxic nodular goitre

Question 49

what happens in autoimmune hyperthyroidism

Answer 49

produce antibodies similar shape to TSH

Question 50

what do antibodies similar to TSH cause

Answer 50

turns on T3 and T4 production process uncontrollably

Question 51

primary hyperparathyroid levels=

Answer 51

very little TSH, very high T3 and T4

Question 52

symptoms of hyperthyroidism (5)

Answer 52

``` weight loss lack of energy heat intolerance Anxiety increase appetite ```

Question 53

Giotre=

Answer 53

enlarged thyroid

Question 54

graves disease=

Answer 54

hyperthyrodism

Question 55

treatment for hyperthyroidism

Answer 55

medical radioactive iodine surgical

Question 56

drug treatment for hyperthyroidism

Answer 56

Thionamindes | Beta blockers

Question 57

e.g 2 thionamindes

Answer 57

Carbimazole | Propylthiouracil

Question 58

what do Thioamindes do

Answer 58

inhibit iodide oxidation by thyroid peroxidase

Question 59

beta blockers

Answer 59

alleviate sympathetic manifestations rapidly

Question 60

what is the surgical procedure for hyperthyroidism

Answer 60

thyroidiectomy