Question | Answer |
What is the formal name for the mineral calcium? | hydroxyapatite |
Where is 99% of calcium found in the body? | bone, teeth |
How is Ca transported across the intestinal epithelia? | active transport using Ca binding proteins |
Where is Ca absorbed the most? | duodenum and jejunum |
When is calcium uptake more active? When calcium levels in the body are high or low? | When calcium levels are low |
What form of vitamin d has the most influence on calcium absorption in the intestines? | calcitriol (D3) |
When Ca concentrations are very high what is another way calcium gets across the intestinal membrane of the ileum and the colon? | When concentrations are very high it just diffuses paracellularly |
What are some physiological factors that affect Ca absorption? | vitamin D status,
life stage (infancy pregnancy and old age),
inhibition of absorption |
In general how does vitamin d status affect Ca absorption (increasing and decreasing) | too little vit d can't absorb Ca, too much vit d absorb too much Ca and have hypercalcemia |
what are some inhibitors of Ca absorption | phytic acid, oxalic acid, fat malabsorption, high intake of other divalent cations (Mg2+, Fe2+) |
what are some factors that would increase the absorption of Ca | |
How is Ca transported in the blood | protein bound (albumen), free ionized form, bound to P.C.S. (phosphate, citrate, sulfate) |
Which way does Ca transport through the blood the most | Free ionized form |
How is Ca excreted | Urine, feces, sweat |
What are the major functions of Ca in the body | Structural, muscle contraction, blood clotting, nerve conduction |
What is PTH's effect on the kidney | PTH causes increased activity of 25 hydroxylase which converts calcidiol to calcitriol, increases reabsorption of Ca and excretion of P |
What is PTH's effect on bones | PTH stimulates osteoblast activity to indirectly increase osteoclast activity causing an increase in resorption |
What are the effects of vitamin d on the kidneys | increased expression of calcium binding protein (calbindin), increased reabsorption (Acts on the tubules in the kidneys to reabsorb calcium from the pee) |
What are the effects of vitamin D on bones | interacts with osteoblasts to indirectly stimulate osteoclast activity (increased bone resorption) |
What are the effects of vitamin D on the intestines | interacts with enterocytes to increase expression of calbindin and increase the expression of transporters for calcium in and out |
osteoblasts have receptors for ______ hormone and osteoclasts have receptors for ____ hormone | PTH, calcitonin |
Vitamin D has an effect on ___ absorption in the intestines, where PTH has no effect | Ca |
What is the hormone that is released in response to high calcium levels (or hypercalcemia) and which organ secretes it | calcitonin, thyroid |
Name 2 effects of calcitonin | inhibits PTH secretion, decreases the activity of osteoclasts |
What are some deficiency symptoms of hypocalcemia | muscle pain and spasm, osteoporosis (theres more just fyi) |
What are some possible causes of hypocalcemia | renal disease, liver disease, parathyroid issues (hypoparathyroid), low vitamin D status, malabsorptive disorders |
What are "Bones, stones, moans, and groans” symptoms for | hypercalcemia |
What does bones, stones, moans, and groans stand for | Bone: ache, high risk of fracture (impair normal bone turn over), Stones: kidney stones: inappropriate deposition in the kidney, Moans: muscular, groans: neurological issues |
What are some causes of hypercalcemia | vitamin D toxicity, over active parathyroid (hyperparathyroidism), cancer |
What are good food sources of Ca | dark leafy greens, dairy, beans |
the distribution of phosphorus in the body is: bones, muscles, blood | |
Where is phosphorus mainly absorbed and by what means | duodenum and jejunum, by phosphate transporters |
Is phosphorus influenced by vitamin d | yes but not as much as Ca |
How is phosphorus transported in circulation | lipoproteins |
How is P regulated and what organ also has regulatory effects on it | regulated by PTH and the kidney regulates it by excreting and reabsorbing |
What are some functions of phosphorus in the body | need it in every cell of our body: phosphorylations, energy production and storage (ATP), phospholipid membrane, cell signaling, bones |
is deficiency common | No very rare, present in most foods |
What is one disease state where P is crucial to include | Malnurished person refeeding syndrome where if they have glucose w/o P |
Why is it so crucial to have P with glucose in feeding tubes | Because the first step glucose goes through when it enters cells is it has to be phosphorylated and without P you can undergo metabolic stress and die |
What are common foods containing P | dairy, legumes, nuts, grains |
What are some factors that have an increasing effect on Ca absorption | acidic environment, lactose, protein, amount ingested, low calcium status, vit d |
What are factors that have a decreasing effect on Ca absorption | citric acid, oxalic acid, low vit d, malabsorption of fat, foods high in competing divalent cations |