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26 Cards in this Set
- Front
- Back
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where is the thryroid
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in next, below layrnx
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what kind of hormone does the thyroid produce
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ones that control rate of metabolic processes throughout the body
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where are the 4 parathyroid glands located
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posteriord side of thryroid
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what do the parathyroid glands do
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control serum calcium levels
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what is the isthmus
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small bands of tissue that join the two lobes of the thyroid gland. they cross the anterior surface of the trach/larynx at the cricoid cartilage
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what are C cells
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parafollicular cells of the thyroid gland
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what is the origin and function of calcitonin
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origin: c cells, thyroid
function: lowers serum ca by inhibiting osteclasts |
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what do osteoclasts do?
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a type of bone cell that removes bone tissue by removing its mineralized matrix and breaking up the organic bone
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how are thyroid hormones regulated?
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through a negative feedback system
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what structures are involved in the negative feedback system of the thryoid gland secretions?
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hypothalamus
ant pit thyroid |
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what is TRH
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thyrotropin
releasing hormone |
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where is TRH synth and stored
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hypothalamus
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what does TRH stimulate the release of
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thyroid stimulating hormone
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when does TRH increase
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increases with exposure to cold, stress, and decreased T4 levels
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T4 function
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regulates:
protien, fat, CHO catbolism in all cells |
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T3 function
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metabolic rate of cells
body heat production insulin agonist GH secretion skeletal maturation CNS development muscle tone/vigor cardiac rate, force, output secretions in GI tract resp rate/oxygen utilzation calicium mobilization RBC production lipid turnover free fatty acid release chol systhesis |
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what influences the amount of T3 secreted
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gender
pg ^gonadal/adrenocort steroids extreme cold=^ levels nutritional state chemicals GHIH= decreased levels dopamine=decerased levels catecholamines=^ levels |
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how does the level of calcitonin change in the presence of elevated serum calcium
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increases
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what is the function of calcitonin
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lowers serum calcium, phosphate
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effects of TSH
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^ in release of stored thy horm
^ iodide uptake and oxidation ^ thy horm synth ^ synth and secret of prostaglandins by the thy |
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TH acts on these structures
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thy
ant pit |
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what is thyroid secretion controlled by
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negative feedback system
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how does the negative feedback system influence TH
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TH> decrease TRH/TSH> decrease TH
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TH syth stimulated by
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pit TSH
low serum iodide levels drugs interfering w/ thy gland uptake of iodide from blood |
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TH synth summerized
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uniodinated thyroglbulin produced by ER of follicular cells
tyrosine incorperated into thyroglobulin iodide pumped from blood into the colloid cell iodide attaches to tyrosine in thyroglobulin cell iodinated tyrosine forms thyroid hormones depending on how many iodine atoms combine with tyrosine determines whether T3/T4 (1+2=T3) (2+2=T4) hormones stored attached to thyroglobulin within colloid until released |
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what is the ratio of T3/4 being made?
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3: 10%
4: 90% |
