thyroid martin Flashcards
the thyroid gland consists of tow lateral lobes connected by the _
it is located blow and anterior to the _
isthmus
larynx
what are some abberant locations of thyroid tissue
lingual, thyroglossal, substernal
describe the HPA axis for thyroid
- stimulus like low body temperature will cause the hypothalmus to secrete TRH
- TRH stimulates the AP to secretes TSH
- TSH acts on the thyroid gland to release TH from the follicular cells
- TH through negative feedback stops the production of TSH and TRH when there are adquate levels
TH (thyroid hormones) essential action in a _ in basal metabolic rate
increase
example of TH stimulation
increased fatty acid mobilization, increased heart rate, hypertrophy, increases cholesterol synthesis, increased gluconeogensis, increased protein catablism, increased growth, ,increased resportion of bone
decreased TSH and increased GH
Th _ growth hormone
increases
thyroglobulin is synthesized and stored in _. Iodide is transported into the cell and incorporated into TG (thyroglobulin) to form _ _ , TG is _ and cleaved to release _ and _
colloid
idodinated tyrosines
endocytosed
T4 and T3
the thyroid is divided by thin _ into lobules there are about 20-40 lobules, they are lined by _ to _ _ epitheliun abd are filled with _ positive thyroglobulin
septae
low cuboidal (not active)
to low columnar epithelium (active)
PAS+ thyroglobulin
the thyroid follicle is formed by simple _ to low _ epithelium = follicular epithelium
cuboidal
columnar
follicular cells aka _ cells produce
principle
T4 and T3
_ induces follicular cells to transform from cuboidal to columnar
TSH
_ and _ regulate cell and tissue basal metabolism, _ production, and influence _ growth
T3 and T4
heat production
body growth/development
follicles contain colloid what is a prinicple component of colloid?
thyroglobulin which is an idoniated glycoprotein (gel like substance)
thyrogloblin is not a hormone is stores?
inactive form of thyroid hormones
thryoid follicles convert thyroglobulin to _ and to a lesser amount of _
T4
T3 (lesser)
_ and _ trasnport T4 and T3 to the periphery
thyroxine-binding globulin and transthyretin
_ proteins keep T3 and T4 unbound or free in narrow limits
binding
majority of T4 deionitaed to _ in the periphery which binds to thryoig hormone nuclear receptors with way greater affinity
T3
multiprotein hormone receptor complex binds to _ in target genes regulating their transcription
thyroid hormone response element
upregulation of _ and _ catabolism plus stumulation of _ synthesis results in a new increase in basal metabolic rate
carbohydrate and lipid catabolism
protein
thyroid hormone has a critical role in _ development of fetus and neonate
brain
when the TSH reaches its TSH receptor in the thyroid what happens
Gs protein activation increased inctracellular CAMP which stimulated thyroid growth
T3 and T4 go to the thyroid hormone receptor and alter gene expression
what is a goitrogen?
this is an inhbitor of T3 and T4 synthesis with an increase in TSH leading to a hyperplastic goiter
what is propylthiouracil (PTU)
an antithyroid agent that inhibits oxidation of iodide
thus blocking thyroid hormone production
also blocks peripheral deiodination of T3 to T4 (getting rid of symptoms)