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22 Cards in this Set
- Front
- Back
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When does the thyroid gland respond to TSH in the developing fetus?
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Week 22
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What is the result of the congenital absence of the thyroid gland?
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Irreversible neurologic damage in the infant
(cretinism) |
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Where is the thyroid located exactly?
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Below the larynx-- the lobes rest on the sides of the trachea
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In a state of iodide deficiency, will TSH synthesis increase or decrease?
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Increase
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Besides hormone production, what stimulatory effects does TSH have on the thyroid gland?
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Growth and vascularization
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Describe the exocrine phase of thyroid hormone production
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1. Uptake of iodide from the blood
2. Synthesis of thyroglobulin 3. Incorporation of iodine into tyrosyl residues of thyroglobulin by TPO |
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Describe the endocrine phase of thyroid hormone production.
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1. Endocytosis of iodinated thyroglobulin into follicular cell
2. Phagosome-lysosomal fusion 3. Lysosomal degradation of Tb and release of T3 and T4 4. T3 and T4 leave cell on basolateral side to enter circulation |
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Where is the thyroid hormone receptor located and what is it bound to?
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Located in the nucleus
Bound to thyroid hormone-responsive element (TRE) |
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The maintenance of Ca2+ homeostasis is regulated by what 3 factors?
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1. PTH
2. Vitamin D 3. Calcitonin |
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How is the release of PTH from chief cells inhibited?
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Serum Ca2+ binds to Ca2+-sensing receptor (CaSR), triggering intracellular signals suppressing the secretion of parathyroid hormone.
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Does Ca2+ enter chief cells to regulate PTH secretion?
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No, it acts as a ligand, binding to an extracellular region of the Ca2+-sensing receptor
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PTH regulates Ca2+ and phosphate balance by acting on which two main sites?
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1. Bone tissue
2. Uriniferous tubules |
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PTH binds to a cell surface receptor of the osteoblast to regulate the synthesis of 3 proteins essential for the differentiation and function of osteoclasts -- what are these 3 proteins?
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1. M-CSF ligand
2. RANKL 3. Osteoprotegerin |
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Which protein is produced by osteoblasts and induces the differentiation of monocytes into immature osteoclasts?
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M-CSF ligand
(macrophage colony-stimulating factor) |
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What is the result of RANK-RANKL interaction--and which cells are interacting?
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Osteoblast-osteoclast interaction
This interaction induces the differentiation of the osteoclast precursor into a resting osteoclast |
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Name the decoy protein that blocks binding of RANKL to the RANK receptor to prevent completion of the final differentiation of functional osteoclasts.
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Osteoprotegerin.
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What condition results from inactivating mutations of one or both alleles of the CaSR?
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Familial benign hypercalcemia
(Results in an increase of parathyroid hormone secretion) |
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Which condition results in a failure of tissues to respond to PTH?
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Idiopathic hypoparathyroidism
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What is the result of an inactivating mutation of the CaSR?
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Increased secretion of PTH
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What is the result of an activating mutation of the CaSR?
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Decreased secretion of PTH
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What type of drugs activate CaSR, reducing pathologic elevations of parathyroid hormone?
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Calcimimetic drugs
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What type of drugs block the CaSR, and may be useful for the treatment of osteoporosis?
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Calcilytic drugs
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