Thyroid and Parathyroid Flashcards
Between which levels can the thyroid be found?
C5 and T1
Thyroid helps control of m_________ and regulation of g_____ and has multiple roles in development
metabolism and regulation of growth
Thyroid gland produces 2 iodine containing molecules - t________ (T4) and triiodothronine (T3)
thyroxine
1) ___ binds to TSHR
TSH
2) _- uptake by NIS
I
3) i__________ of Tg tyrosyl residues by TPO (thyroperoxidase)
Iodination
4) Coupling of iodotyrosol residues by TPO
5) Export of mature Tg to colloid where it is stored
T3 is produced by mono-deodination of __
T4
Thyroid is produced by f_________ thyroid cells
follicular
The precursor of thyroid is…
thyroglobulin
Iodine is absorbed from the ____________ and concentrated in follicles
bloodstream
Thyroperoxidase binds i_____ to tyrosine residue in thyroglobulin molecules to form MIT + DIT
iodine
MIT + DIT =
T3
DIT + DIT =
T4
In hyperthyroidism there is ___ serum TSH, ____ serium free T4 and ____ serum free T3
low, high, high
In hypothyroidism, there is ____ serum TSH, ___ serum free T4, ___ serum free T3
high, low, low
What proteins can bind to T4 and T3?
TBG (thyroxine binding globulin), transthyretin, albumin
What is a common condition causing hyperthyroidism?
Graves’ disease
What are signs and symptoms of hyperthyroidism?
Tachycardia, Atrial fibrillation, shortness of breath, ankle swelling
Weight loss, BMR increases, diarrhoea, increased appetite
Tremor, anxiety, sweating, myopathy
Sore and gritty eyes, double vision, staring eyes, pruritus (itching)
Hypothyroidism can be due to the e_____ for making thyroxine being attacked
enzyme
Symptoms and signs of hypothroidism
Bradycardia (fewer beta 1 receptors in heart), heart failure, pericardial effusion
Weight gain, constipation
Myxoedema, erythema ab igne (rash), vitiligo (pale patches)
Depression, psychosis, carpal tunnel syndrome
What is the purpose of the parathyroid gland?
Maintaining serum calcium levels
Which organ will be impaired if serum calcium drops too low?
Heart
Where and how does PHT (parathyroid hormone) work?
Kidney (DCT - prevent losing too much Ca2+)
Increases intestinal Ca2+ absorption (via activation of vitamin D)
Increases calcium release from bone (stimulates osteoclast activity)
Decrease phosphate reabsorption
What is calcium bound to in the serum?
Albumin
What stimulates PTH secretion?
Hypocalcaemia
True or false: PTH increases bone resorption
True
PTH affects kidney by increasing urinary p________ and decreases urinary c_______
phosphate
calcium
PTH affect intestine by __________ calcium and phosphate absorption
increases
The active form of vitamin D i_______ transcription of PTH
inhibits
For raised serum PTH, what could cause primary HPT?
Parathyroid tumour
Causes hypercalcaemia and low serum phosphate
Loss of negative feedback from hypercalcaemia
For raised serum PTH, what could cause secondary HPT?
Renal disease (increased phosphate, decreased activation of vitamin D)
For raised serum PTH, what could cause tertiary HPT?
Long-standing HPT leads to irreversible parathyroid hyperplasia
(usually seen when renal disease corrected eg by transplantation)
In primary HPT there is a problem in…
the gland itself
True or false: In secondary HPT there is not a problem in the gland
True
(Problem in kidney)
What produces calcitonin?
thyroid c-cells
The superior and inferior thyroid arteries are branches off…
external carotid artery
What is arrangement of cells in the thyroid?
Follicular cells with central colloid and surrounding c-cell
What inhibits the hypothalamus from secreting TRH and anterior pituitary secreting TSH?
T3 and T4
What does iodine bind to within thyroglobulin molecules?
tyrosine residues
What enzyme helps binding of iodine to tyrosine residues?
thyroperoxidase
Hyperthyroidism causes an overactivity of the __________ system leading to increased gut motility and diarrhoea
sympathetic
True of false: PTH is secreted in response to high calcium
False
Secreted when low calcium
True or false: PTH is secreted in response to high phosphate?
True
(PTH increases urinary phosphate excretion)
True or False: vitamin D increases calcium absorption from intestine?
True
Where is calcitonin secreted from?
C cells of thyroid gland
What does calcitonin do?
Reduces blood calcium by inhibiting bone resorption and increasing excretion of calcium
The active form of vitamin D i_______ the transcription of PTH
inhibits
PTH translation is inhibited by increased s____ c______
serum calcium
