thyroid gland

Question 1

how many lobes does the thyroid gland have

Answer 1

2

Question 2

connected by

Answer 2

isthmus

Question 3

what extra lobe do somepeoplpe have

Answer 3

pyramid

Question 4

what is the thyroid made up of

Answer 4

follicles

Question 5

describe the strcuture

Answer 5

follicular (circular) cells on outside

with colloid in midlle

Question 6

what is colloid made up of

Answer 6

extracellular fluid

Question 7

what other cell

Answer 7

parafollicular cells

Question 8

function

Answer 8

secrete calcitonin

Question 9

what 2 glands are embedded in thyroid

Answer 9

parathyroid glands (superior and inferiori)

Question 10

which nerves runs vlose and supplies vocal cords

Answer 10

left recurrent laryngeal nerve

Question 11

what do the para thyroid glands secrete

Answer 11

hormone importnat for calcium metabolism

Question 12

in embryo where does the thyroid start of

Answer 12

base of tongue
develop of thyroglossal duct 
divide in 2 lobes 
Duct disappears leaving foramen caecum
Final position by week 7
Thyroid gland then develops

Question 13

how are blood vessels shown in histology

Answer 13

red

Question 14

what are the White line/dot-

Answer 14

where the thyroid hormone is made

Question 15

how is t3/t4 sythesised

Answer 15

TSH- arrives via blood, binds to TSH R
Na+ and I-, enter by sodium iodine co transporter then iodide transported via another receptor to colloid
Become oxidesed called iodination to become iodine

TG (thyroglobulin) is made as a result of TSH R being bound(?) ]

TG binds to iodine
to produce MIT and DIT

coupling reaction to produce t3 t4

TPO and h2o2 catalysis the reaction

TG prohormone

Question 16

which amino acid residue is iodinated in the TG

Answer 16

tyrosine

Question 17

structure

Answer 17

aromatic ring

Question 18

only one iodine added

Answer 18

3 monoiodotyrosine (MIT)

Question 19

2 iodine

Answer 19

3,5-DIIODOTYROSINE

Question 20

3-MONOIODOTYROSINE +
3,5-DIIODOTYROSINE
MIT + DIT

Answer 20

T3

Question 21

3,5-DIIODOTYROSINE
+
3,5-DIIODOTYROSINE
DIT + DIT

Answer 21

t4

Question 22

which is the active hormone

Answer 22

t3

Question 23

how is t4 converted to active t3

Answer 23

Deiodinated to triiodothyronine (T3), its bioactive form, in target tissues

Question 24

if deiodinated in different position

Answer 24

Also deiodinated in a different position to produce reverse T3 (inactive)

Question 25

which enzyme deiodinates

Answer 25

deiodinase enzyme

Question 26

so t4 is a what sort of hormone

Answer 26

prohormone

Question 27

how are t3 t4 transported in blood

Answer 27

Mostly bound to plasma proteins

Question 28

is it active when bound

Answer 28

no

Question 29

what affect does t4/t3 have on a gene

Answer 29

Target tissue have the diodinase enzyme T3 enters nucleus T3 binds to thyoid receptor Altered gene expression

Question 30

what is cretinism

Answer 30

severe deficiency of thyroid hormone in newborn

Question 31

how is it tested at birth

Answer 31

TSH measured in new-born infant’s heel-prick test

Question 32

what does thyroid hormone do

Answer 32

↑Basal metabolic rate Protein, carbohydrate & fat metabolism Potentiate actions of catecholamines (e.g. tachycardia, lipolysis) Effects on the GI, CNS, Reproductive systems ``` ↑glucose absorption ↑gylcogenolysis Gluconeogenesis ↑lipolysis ↑protein synthesis & degradation ``` ↑cardiac output

Question 33

how is homostasis achieved when TRH causes TSH causing T3/T4 in posistive cylce

Answer 33

inhibited by negative feedback by increase in T3 T4 ((Wolff-Chaikoff effect) Iodine can inhbit production of t3 t4 in large amounts Large amount of potassium iodine given to stop production

Question 34

which hormone can also inhibt

Answer 34

omatostatin- inhibit production of TSH

Question 35

Are thyroid disorders more common in men or women, or the same?

Answer 35

Women (4:1 ratio)

Question 36

why

Answer 36

???? Over time, evolved to carry baby, baby has lots of other antigesn, so women immune system is diffrenent

Question 37

Is an overactive thyroid gland or an underactive thyroid gland more common?

Answer 37

The same

Question 38

what causes Primary hypothyroidism

Answer 38

autoimmune | surgery- removal of thyroid

Question 39

what happens in Primary hypothyroidism to thyroxine and TSH levels

Answer 39

Thyroxine levels decline | TSH levels climb

Question 40

what are 2 diseases associated with hypo

Answer 40

Graves can cause hypo but more rare mostly hyper | Hashimoto’s thyroiditis

Question 41

``` signs ans symptoms of hypo in hair brain thyroid face voice skin weight bowel heart cold/hot ```

Answer 41

``` hair- hair loss, receding, thin brain- fatigue, memory impairment, depression thyroid- enlarge face-swollen, voice-deep weight-increase with reduced appetite bowel-Constipation heart- Bradycardia cold intolernace- always hot ``` Affects sypmathtic nervous system- everything slows down

Question 42

drug to treat hypo

Answer 42

Levothyroxine

Question 43

what is it similar to

Answer 43

Levothyroxine- similar to t4 | Deiodinated in the same way to give you t3

Question 44

can it treat hyper

Answer 44

Hyper- high anti thyroid hormone, and give back what they need to survive

Question 45

why not give t3

Answer 45

Expensive t3 T4 cheap No evidence it works better than t4

Question 46

what haooens to thyroxine and TSH levels in hyper

Answer 46

Thyroxine levels rise | TSH levels drop

Question 47

disease

Answer 47

Graves’ disease – whole gland smoothly enlarged and whole gland overactive Toxic multinodular goitre Solitary toxic nodule

Question 48

sign and symptoms

Answer 48

nervousness,irritability, insomnia, depression ``` broken hair/hairloss enlarge thyroid weight loss tachycardia Heat intolerance Weight loss with increased appetite Myopathy Mood swings Diarrhoea Tremor of hands Palpitations Sore eyes, goitre eye- Exophthalmos- problem gritty, dry, don’t close at night ```

Question 49

what causes enlarged thyroid

Answer 49

Antibodies bind to and stimulate TSH receptor in the thyroid | Smooth goitre