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Physiology > thyroid > Flashcards

thyroid Flashcards

1
Q

making thyroid hormones

A

tyrosine becomes iodinated and then 2 of these are conjugation to make T3 or T4

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2
Q

where are the parathyroid glands location

A

4 on posterior surface in 4 corners of thyroid

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3
Q

colloid

A

glycoprotein, surrounded by connective tissue

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4
Q

what does T3 do?

A

responsible for most thyroid activity - half life of 1 day

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5
Q

what does T4 do?

A

largely converted to T3 intracellularly - half life of 7 days

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6
Q

thyroid hormones in blood are bound to?

A

albumin
thyroxine binding globulin
transthyretin
most of T3 and T4 are bound and so these have to broken down to be measured

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7
Q

affect on nucleus

A

activates nuclear receptors to activate DNA trasncription

normally occupied by inhibitory repressors which are displaced by T3 to start activation

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8
Q

Affect on mitochondira

A

direct action to increase oxidative phosphorylation

stimulates mitochondrial DNA transcription

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9
Q

possible causes of hypothyroidism

A

hypothalamic damage - less TRH from surgery
anterior pituitary damage - less TSH from surgery
thyroid damage - exposure to radioactive iodine, drugs or surgery
autoimmune - hashimoto’s disease
congenital - genetic/ developmental/ iodine deficiency
iodine deficiency - adult/ congenital

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10
Q

symptoms of underactive thyroid

A 
slow metabolic rate 
tiredness
cold intolerance
weight gain
bradycardia 
hypotension
slow reflexes and speech 
dry skin 
thinning hair 
mucopolysaccharide deposits - around eyes
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11
Q

hashimoto’s disease

A

normal immune tolerance fails
autoreactive CD4+ T cells recruit B cells and CD8 + T cells to the thyroid
Anti-thyroid peroxidase

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12
Q

macroglossia

A

large tongue

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13
Q

congenital hypothyroidism

A 
coarse features
macroglossia
floppy/ poor feeding
mental retardation
short stature 
failure to treat causes permanent developmental impairment - cretinism
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14
Q

causes of hyperthyroidism

A

TSH secreting tumour
autoimmune - graves
adenoma - tumour that secretes hormones
over treatment

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15
Q

hyperthyroidism

A

increase protein synthesis and muscle bulk
increased metabolism
increased heat production
increased oxygen consumption

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16
Q

symptoms of hyperthyroidism

A 
weight loss
heat tolerance
tremor
tachycardia 
arrhythmias
muscle weakness
diarrhoea
goitre - highly vascularised 
eye sides - exophthalmus
17
Q

exophthalmos

A

inflammatory process behind eyes

can threaten vision

18
Q

graves disease

A

normal immune balance disrupted
anti-TSH receptors Antibodies generated that mimic TSH and stimulate receptor after binding
increases T£ and T4 synthesis

19
Q

stage 1 of making T3 and 4

A

Na+/ I- symporter traps iodine ions in the cell at a higher concentration than outside

20
Q

Stage 2 of making T3 and 4

A

iodination needs iodine not iodide and so Thyroid peroxidase oxidises iodide to free iodine using peroxide

21
Q

stage 3 of making T3 and 4

A

thyro-globulin is the storage vehicle for T3 and 4 in follicles

22
Q

stage 4 of making T3 and 4

A

iodination, tyrosine conjugation

23
Q

transportation

A

thryo-globulin transports them in and out of colloid by exo and endocytosis

24
Q

stage 5 of making T3 and 4

A

cleavage - loss of protein and T3 and 4 can be released

25
Q

what does TSH stimulate

A

Na/I- symporter

thyroglobulin synthesis and exocytosis into colloid

26
Q

affect on cell membrane

A

cell surface GPCR receptor which indirectly stimulates nuclear DNA transcription

27
Q

thyroid hormone affect on organs

A

affects brain, liver, kidneys, muscle and fat

28
Q

what else do the thyroid hormones do?

A

increase basal metabolic rate - generates heat and uses O2

  • increases force and rate of contraction of heart
  • increase sympathetic NS
  • increases protein synthesis and growth
  • increases cerebral activity
  • increases action of GH
29
Q

what are the types of thyroid cancer?

A

papillary - slow growing and linked to radiation
follicular
medullary - parafollicular C cells
anaplastic - undifferentiated

30
Q

presentation of thyroid cancer

A

painless neck lump

lack of hormone secretion

Physiology (46 decks)

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