Thyroid anatomy and physiology

Question 1

when does the thyroid gland form in foetus

Answer 1

4 weeks

Question 2

formation of thyroid gland

Answer 2

Starts off at base of tongue starts descending downwards, goes infront of larynx, migrates all way down to final position- Infront of tracheal rings
Splits into right and left lobe, joined by an isthmus

Question 3

what does the thyroid gland split into and what is it connected by

Answer 3

right and left lobe connected by isthmus

Question 4

how may you clinically see a cyst

Answer 4

if you ask patient to move tongue outwards

Question 5

what do the parathyroid glands secrete

Answer 5

parathyroid

Question 6

how many parathyroid glands are there

Answer 6

4

Question 7

thyroid gland and trachea

Answer 7

encricled around it
4 glands at bakc

Question 8

what hromones does the hyroid produce

Answer 8

thyroxine, calcitonin, t4, t3

Question 9

uniqueness of thyroid gland

Answer 9

Largest endocrine gland, only lobe that you can palpate, only one that requires substances from environment

Question 10

what substance from the environment does the thyroidg land need

Answer 10

iodine

Question 11

basic functional unit of thyroid

Answer 11

follicle
follicular cells
parafollicular cells

Question 12

which type of cells are follicular cells

Answer 12

cuboidal

Question 13

where is t3 and t4 produced

Answer 13

follicular cells

Question 14

where is calcitonin produced

Answer 14

parafollicular cells

Question 15

negative feedback system

Answer 15

hypothalamus produces TRH - stimulates pituitary to produce thyroid stimulating hormone which stimulates the thyroid gland to produce t3 and t4

Question 16

what is t4 converted into

Answer 16

active t3

Question 17

what happens if have appropriate number of thyroid hormones

Answer 17

negative feedback system back to hypothalamus to switch it off so too much isnt produced

Question 18

what happen sif have too little t3 and 4

Answer 18

increased up regulate hypothalamus and pituitary

Question 19

where is thyroglobulin produced

Answer 19

in colloid

Question 20

thyroid hormone synthesis process

Answer 20

Uptake and conc of iodide into follicular cells

Iodide oxidated to iodine

Gets transported into colloid - iodination of thyroigoloubulin

Formation of those two products

Iodine attaches to tyrosine residues to form either mono iodotyrosine unit - one single iodine

Or if two iodines that are attached to thyroglobulin then di-iodotyrosine unit

Mit and dit then have three iodine resisudes in total - t3

If get two di attaching then you get dit and dit- 4 iodine residues- thyroxine

Question 21

what is most thyroid stored as

Answer 21

t4 - thyroxine

Question 22

which is more potent t3 or t4

Answer 22

t3

Question 23

where can t4 be converted to t3

Answer 23

in liver and kidney

Question 24

is t4 biologically active

Answer 24

no, nly t3 is

Question 25

how are t3 and t4 transported

Answer 25

Bound to serum proteins:

thyroxine binding globulin - 70%,

thyroxine binding pre albumin 20%

Albumin 5%

Question 26

can bound hormones enter the cell and regulate it

Answer 26

no only unbound can, so t3 is less tightly bound

Question 27

what is metabolic state linked to

Answer 27

T3

Question 28

effects of thyroid hormone

Answer 28

• Increases metabolic rate by increasing number and size of mitochondria
  ○ Increase oxygen use and rates of atp hydrolysis
  ○ Increase synthesis of resp chain enzymes
  
  • Can effect all cells
  • Increase thermogenesis - feel heat more if overacive thyroid
  • Incrrease glucose uptake so can sustain metabolism
  • wOrks on liver to increase glycogenolysis ; breakdown of glycogn
  • Increases lipolysis- fat breakdown
  • Can work on lungsa nd heart- increases breathing rate and heart rate
    Everything is upregulated

Question 29

what to treat over active thyroid with

Answer 29

beta blocker

Question 30

symptoms associated with hyperthyroidism

Answer 30

Palpitations, tremors, sweats , shakes
everything is fast , hair loss, weight loss, bowels speeding up- diarrhoea - warm palms, anxiety
Increases body responsiveness to adrenaline and sympathetic NS neurotransmitter, noradrenaline by increasing number of receptors

Question 31

how are t3 and t4 degraded

Answer 31

by diodinases - d1,d2,d3

Question 32

what is t4 degraded by and to

Answer 32

by d1 into t3

Question 33

what else can t4 be broken down to besides t3

Answer 33

inactive reverse t3 via d3

Question 34

where is d1 found

Answer 34

liver and kidney

Question 35

where is d2 found

Answer 35

heart and skeletal muscle, cns , fat, thyroid and pituitary

Question 36

where is d3 found

Answer 36

foetal tissue and placenta

Question 37

hypothyroidism clinical features

Answer 37

everything slow , weight gain, slower, sluggish, bradycardia , constipation as bowels have slowes, metabolism slowed, low mood, forgetfulness

Question 38

secondary thyroid issue

Answer 38

things that feed into the issue hypothalamus/ pituitary etc

Question 39

primary issue

Answer 39

failure of the gland

Question 40

what might a lack of iodine cause

Answer 40

hypothyroidism

Question 41

what is a mix oedema crisis

Answer 41

hypothyroid crisis

Question 42

disease of over active thyroid

Answer 42

graves disease
- Autoimmune condition results from own body producing tsh receptor antibodies - they are stimulating antibodies- stimulate thyroid gland to overproduce t4 and t3
Problems with eyes- thyroid eye disease , mild = redness dry eyes, extreme= bulgy eyes

Question 43

what is a goitre

Answer 43

enlarged thyroid gland