the thyroid gland Flashcards
what are the hormones released by this gland
calcitonin and T3, T4
what is calcitonin
a polypeptide hormone produced by c cells that functions in regulating blood calcium levels in conjunction with parathyoid hormone
what is calcitonin secretion dependent on
blood calcium levels
how does calcitonin lower blood calcium levels
inhibit the rate of decalcification of bone by osteoclastic resorption
what produces calcitonin
c cells
what are T3 and T4
iodine containing hormones
what is T3
tri-iodothyronine
what is T4
tetraiodothyronine
how is T4 converted to T3
in general circulation by removal of one iodothyronine
what is the function of T4
regulate basal metabolic rate
what is T4 in relation to T3
the metabolically active form of T3
what is thyroxine
T4
what is secretion of t4 regulated by
thyroid stimulating hormone
what does the thyroid hormone do
store lots of inactive hormone within the extracellular compartments in the centre of the follicles
what is thyrotoxosis
excess of circulating thyroid hormone which causes symptoms due to systemic effect of the thyroid hormone
what can thyrotoxicosis lead to
graves disease
what is graves disease
hyperfunction of the thyroid gland, an autoimmune disease
what are the symptoms of graves disease
exophthalmos (puffy eyes) and non pitting edema of the lower limbs (fluid accumulation)
what is hypothyroidism
lack of production of thyroid hormone leading to weight gain, tiredness and poor tolerance to cold weather
what is hashimotos disease
the thyroid acini are destroyed as the gland is infiltrated by lymphocytes and plasma cells. leads to fatigue, weight gain and depression
which epithelium lines the thyroid follicles
simple cuboidal
what do the septa of the gland convey
blood supply, lymphatics and nerves
what do thryoid follicles store
thryoglobulin and iodinated glycoprotein
what is the storage form of T4
thyroglobulin