Endocrine Physiology Flashcards
What happens with the vitamin D3 in the liver?
In the liver, vitamin D3 is converted to 25-hydroxycholecalciferol
What stimulates the PTH formation?
The reduction in concentration of calcium in the ECF (extracellular fluid). Formation of 1,25-dihydroxycholecalciferol also increases when the calcium concentration in the ECF falls (p607-608)
What happens with the 25-hydroxycholecalciferol in the cortex of the kidney?
25-hydroxycholecalciferol is converted to 1,25-dihydroxycholecalciferol is a reaction stimulated and tightly controlled by PTH
What does the 1,25-dihydroxycholecalciferol in th epithelial cells of the small intestine stimulate?
They stimulate the formation of:
- calcium binding protein
- calcium-stimulated ATPase
- alkaline phosphatate
What stimulates the osteoclast activity and formation of new osteoclast?
PTH and 1,25-dihydroxycholecalciferol
What does the calcitonin do?
It decreases the absorptive capacity of osteoclasts and decreases the rate of formation of new osteoclast
What decrease renal calcium excretion?
The increase of PTH
What is the enamel composed of?
Dense crystals of hydroxypatite embedded in a tight meshwork of protein fibers similar to keratin in hair.
What is dentine composed of?
Hydroxapatite crystals embedded in a strong meshwork of collagen fibers, structure similar to bone
What is thyroid gland composed of?
It is composed of large follicles surrounded by a single layer of cell and filled with a proteinaceous material called colloid
What is the primary constituent of colloid?
The large glycoprotein thyroglobulin, which contains the thyroid hormones in its molecule
What decrease the iodide transport by competitive inhibition?
Thiocyanate and perchlorate
What enzyme oxi p 580 thyroid peroxidase
Bibibi
How does the vitamine D3 form in the skin?
In the skin, 7-dehydrocholesterol is converted by UV light to vitamin D3
