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18 Cards in this Set
- Front
- Back
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What type of secretion is vitamin D
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hormone, fat soluble
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What is vitamin D
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major hormone involved in calcium metabolism and skeletal remodeling
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what is a prohormone
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produced @ one site, functions at another site
(ie. vitamin D) |
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2 forms of vitamin D
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1. vitamin D2 (ergocalciferol)
2. Vitamin D3 (cholecalciferol) |
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What UV wavelength is required to activate Vit D
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UV 280-320 nm
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7-dehydrocholesterol
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precursor for cholesterol
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where is 7-dehydrocholesterol found
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abundant in skin, or diet (if skin insufficient)
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decreased plasma [Ca2+]
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stimulates chief cells to secrete PTH
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increased PTH-->?
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stimulates:
1-a-hydroxylase production (renal enzyme) |
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1-a-hydroxylase production--> ?
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activates vit D in kidney
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what is the active form of vit D
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[1,25 (OH)2 D3]
aka. calcitriol |
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increase in Vit D--> ?
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increased blood [Ca2+}
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increased blood [Ca2+]--> ?
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2 things:
decreased PTH Increased Calcitonin |
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Effects of Calcitonin on blood Ca2+
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DECREASED BLOOD CA2+:
- increases osteoblast activity - decreases renal absorption - decreases GI absorption - binds to osteoclasts--> decreases bone resorption |
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Effect of Calcitonin on 1-a-hydroxylase (renal enzyme)
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decreases 1-a-hydroxylase (renal enzyme)
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Effect of decreased 1-a-hydroxylase (renal enzyme)
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decreased Vit D activation
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VDR locations (vitamin D receptors)
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Bone, skeletal muscle, immune/phagocytic functions, pancrease B cells
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how do chief cells (parathyroid) sense decreased calcium levels?
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Ca2+ receptors
located on chief cells (parathyroid) |
