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31 Cards in this Set
- Front
- Back
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What is the daily calcium intake recommendation for healthy children and adults?
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750 mg
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What is the daily calcium intake recommendation for teenagers, pregnant women, and individuals with
healing fractures? |
1500 mg
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What is the daily calcium intakrecommendation for lactating mothers?
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2000 mg
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What is the mechanism of calcium absorption in the duodenum?
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Active transport
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What is the mechanism of calcium absorption in the jejunum?
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Passive diffusion
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What is the mechanism of calcium absorption in the kidney?
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Proximal tubular resorption
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What percentage of total body calcium is within plasma?
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1%
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What are the relative proportions of bound vs. unbound plasma calcium?
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Bound = unbound
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What are the two principal regulators of plasma calcium concentration?
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PTH
1,25-vitamin D |
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What are the relative proportions of bound vs. unbound plasma phosphate?
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Unbound predominates
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What is the principal site of phosphate resorption within the kidney?
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Proximal tubule
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What type of molecule is parathyroid hormone (PTH)?
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Peptide
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Where is PTH produced?
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Chief cells of the parathyroid gland
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What is the stimulus for release of PTH?
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Low plasma calcium concentration
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What receptor detects calcium concentration?
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Calcium sensing receptor (CaSR)
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In what organ and gland can this receptor be found?
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Kidney
Parathyroid gland |
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What type of receptor is CaSR?
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G-protein-coupled receptor
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What are the three effects of CaSR activation within the parathyroid gland?
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PTH secretion
PTH gene expression Cellular proliferation |
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In what organ and in what cells can PTH receptors be found?
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Kidney
Osteoblasts |
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What are PTH’s two actions on the kidney?
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Increase 1,25-vitamin D production
Decrease resorption of renal phosphate |
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What are PTH’s three actions on the bone?
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Stimulate osteoblasts
Osteoblasts produce RANK ligand RANK ligand stimulates osteoclasts |
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What is the net effect of PTH on plasma calcium and phosphate concentrations?
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Increased plasma calcium
Decreased plasma phosphate |
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What type of molecule is 1,25-vitamin D?
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Steroid
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As vitamin D is activated to 1,25-vitamin D, what are the two sites of hydroxylation?
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First: liver
Second: kidney |
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What are the three stimuli for release of 1,25-vitamin D?
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Low serum calcium concentration
Low serum phosphate concentration Elevated PTH levels |
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What are the two effects of 1,25-vitamin D?
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Increased intestinal absorption of calcium and phosphate
Increased osteoclast activity |
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What is the net effect of 1,25-vitamin D on plasma calcium and phosphate concentrations?
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Increased plasma calcium
Increased plasma phosphate |
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What type of molecule is calcitonin?
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Peptide
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Where is calcitonin produced?
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Clear cells (parafollicular cells) of the thyroid gland
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What is the stimulus for release of calcitonin?
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Elevated serum calcium
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What is the effect of calcitonin?
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Inhibits osteoclast activity
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