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26 Cards in this Set
- Front
- Back
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What is the optimal range for calcium in the blood?
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8.5-12.2 mg/dl
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Which organs are important in maintaining good calcium levels and bone health?
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(1) Parathyroid
(2) Skin (3) Intestines |
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What are the two main modulators of Calcium?
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(1) Parathyroid Hormone
(2) Vitamin D |
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What is the order of Vit D metabolism?
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(1) Skin: 7-dehydrocholesterol to Vitamin D3
(2) Liver: Vitamin D3 to 25-hydroxy-vitamin D3 (3) Kidney: 25-hydroxy-vitamin D3 to 1,25 hydroxy-vitamin D3 |
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Describe the metabolism of Vit D in the skin.
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In the skin, 7-dehydrocholesterol is converted to Vitamin D3 by exposure to UV light.
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Describe Vit D metabolism in the Liver.
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Vitamin D3 is converted to 25-hydroxyl-vitamin D via 25-hydroxylase.
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Describe Vit D metabolism in the Kidney.
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25-hydroxy-vitamin D is converted to 1,25-hydroxyl-vitamin D3 byt the enzyme 1-alpha-hydroxylase.
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What is the active form of Vitamin D called?
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Calcitriol - 3 hydroxyl groups or 1,25-hydroxyl Vitamin D3
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In the parathyroid gland, what spurs the release of PTH?
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Hypocalcemia. Hypercalcemia inhibits PTH's release.
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What is the mechanism of PTH?
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On the parathyroid gland membrane, there is something called a calcium sensing receptor.
When the calcium sensing receptor is bound by Calcium, that leads to a decrease in the secretion of parathyroid hormone. When the receptor is not bound by calcium, it causes the releases of PTH to go up. |
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What is the function of PTH?
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PTH functions to increase the serum concentration of calcium. With regards to bone, the PTH will effect the balance of osteobasts and osteoclasts. With regards to the kidney, it is going to increase the activity of 1-alpha reductase which makes the calcitrion in the body, and thus is going to increase the calcium retention in the kidneys and the intestines, which then increases calcium serum levels.
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What did Goz say that Calcitriol resembled? How so?
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Calcitriol is like steroid hormones and thyroid hormones in that it works through receptors that bind to DNA to work to enhance transcription of certain proteins.
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By what mechanism does the kidney help retain calcium?
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Calcitriol arrives in the kidney cells and stimulates transcription of the protein, CALBINDING.
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What are the actions of CALBINDING?
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(1) bind to the calcium and affect its movement
(2)stimulate the production of calcium channels and increase influx of calcium in the lumen (3) bind to calcium in the cell and will facilitate diffusion (4) stimulate the production of ATPase to pump out more Calcium into the blood. |
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How does calcitriol work in the intestines?
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through calbindings.
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What does PTH do to bone?
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PTH causes osteoblasts to produce
(1) RANKL and Osteoprotegrin |
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What is the function of Osteoprotegrin?
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□ Osteoprotegerin binds to the Rank ligand to prevent it from acting and causing bone overgrowth.
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What does the osteoclasts function after it is activated by the bindingof RANKL and osteoprotegrin?
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(1) have a ruffled border that interacts with the bone
(2) Pumps H+ out of a proton pump - breaks down hydroxyappetite (3) Secretes Cathespin K - breaks down the matrix. |
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What are the functions of RANKL?
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Osteoprotegrin binds to RANKL and (1) causes formation of osteoclasts from its precursors and (2) activates the osteoclasts.
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What qualifies you to have osteoporosis?
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You have osteoporosis if you are 2.5 standard deviates below the average bone density .
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What do bisphosphonates resemble?
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Pyrophosphonates.
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What is the target for bisphosphonates?
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The target is an enzyme called Farnesyl diphosphate synthase.
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By blocking Farnesyl diphosphate synthase, what is accomplished by bisphonates ?
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Blocking Farnesyl diphosphate synthase ultimately blocks small GTPases, a modifying protein necessary in osteoclastic activity - without it - it will atropy.
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What were 2 examples of bisphosphonates?
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(1) Ibroduorinate
(2) Boniva |
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What are the risks of developing osteonecrosis of the jaw when taking bisphosphonates?
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(1) • In 94% of the cases - it is from the high dose of IV dosing. The incidence of osteonecrosis of the jaw is something on the order of 1/10000 to 1/100,000. The incidence is very low.
(2) if you are taking Bisphosphonates and you have a tooth extracted then there is an increased chance of osteonecrosis of the jaw - hard to tell - maybe 1/2000 or 1/10,000. (3) A woman is more at risk than if she has osteonecrosis than if she breaks her hip and is immobilized and dies. |
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What PTH drug is used to treat osteoporosis?
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teriparatide - it actually increases bone density by stimulating osteoblasts-where the action is on the bone buiding rather than the inhibition of bone break down.
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