Thyroid anatomy and physiology Flashcards

1
Q

when does the thyroid gland form in foetus

A

4 weeks

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2
Q

formation of thyroid gland

A

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

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3
Q

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

A

right and left lobe connected by isthmus

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4
Q

how may you clinically see a cyst

A

if you ask patient to move tongue outwards

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5
Q

what do the parathyroid glands secrete

A

parathyroid

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6
Q

how many parathyroid glands are there

A

4

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7
Q

thyroid gland and trachea

A

encricled around it
4 glands at bakc

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8
Q

what hromones does the hyroid produce

A

thyroxine, calcitonin, t4, t3

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9
Q

uniqueness of thyroid gland

A

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

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10
Q

what substance from the environment does the thyroidg land need

A

iodine

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11
Q

basic functional unit of thyroid

A

follicle
follicular cells
parafollicular cells

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12
Q

which type of cells are follicular cells

A

cuboidal

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13
Q

where is t3 and t4 produced

A

follicular cells

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14
Q

where is calcitonin produced

A

parafollicular cells

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15
Q

negative feedback system

A

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

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16
Q

what is t4 converted into

A

active t3

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17
Q

what happens if have appropriate number of thyroid hormones

A

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

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18
Q

what happen sif have too little t3 and 4

A

increased up regulate hypothalamus and pituitary

19
Q

where is thyroglobulin produced

A

in colloid

20
Q

thyroid hormone synthesis process

A

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

21
Q

what is most thyroid stored as

A

t4 - thyroxine

22
Q

which is more potent t3 or t4

23
Q

where can t4 be converted to t3

A

in liver and kidney

24
Q

is t4 biologically active

A

no, nly t3 is

25
how are t3 and t4 transported
Bound to serum proteins: thyroxine binding globulin - 70%, thyroxine binding pre albumin 20% Albumin 5%
26
can bound hormones enter the cell and regulate it
no only unbound can, so t3 is less tightly bound
27
what is metabolic state linked to
T3
28
effects of thyroid hormone
- 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
29
what to treat over active thyroid with
beta blocker
30
symptoms associated with hyperthyroidism
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
31
how are t3 and t4 degraded
by diodinases - d1,d2,d3
32
what is t4 degraded by and to
by d1 into t3
33
what else can t4 be broken down to besides t3
inactive reverse t3 via d3
34
where is d1 found
liver and kidney
35
where is d2 found
heart and skeletal muscle, cns , fat, thyroid and pituitary
36
where is d3 found
foetal tissue and placenta
37
hypothyroidism clinical features
everything slow , weight gain, slower, sluggish, bradycardia , constipation as bowels have slowes, metabolism slowed, low mood, forgetfulness
38
secondary thyroid issue
things that feed into the issue hypothalamus/ pituitary etc
39
primary issue
failure of the gland
40
what might a lack of iodine cause
hypothyroidism
41
what is a mix oedema crisis
hypothyroid crisis
42
disease of over active thyroid
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
43
what is a goitre
enlarged thyroid gland
44