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33 Cards in this Set
- Front
- Back
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what is the major storage site for calcium in the body?
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bone
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what builds new bone?
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calcium moves in as osteoblast build new bone
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what breaks down bone?
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calcium moves out as osteoclasts break down bone
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what happens when osteoclast and osteoblast activity is equal?
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the movement of calcium in and out is equal
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what are some of the functions of Ca+
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nerve & muscle function, blood clotting, enzyme function in many biochemical rxn's
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at what level does blood calcium need to be maintained?
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9-11mg/100ml
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what can happen if calcium levels get out of homeostasis?
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cardiac arrest of too high, respiratory arrest of too low
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what are the 3 ways calcium exists in the human body?
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bound, non-ionized, & ionized
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what is bound calcium?
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it is in the plasma and is non-diffusable across capillaries
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what % of the body's calcium is bound?
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41%
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what is non-ionized calcium?
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it is bound anions-- it is diffusable across capillary beds
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what % of calcium if ionized?
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9%
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what % of calcium is ionized?
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50%
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what is important about ionized calcium?
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it is diffusable across capillary beds and is important in physiological controls
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what happens if there are elevated extracellular levels of calcium?
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it prevents membrane depolarization
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what happens if there are decreased extraceullar levels of Ca+
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it leads to spontaneous action potential generation
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what is the function of PTH?
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it increases Ca2+ extracellular levels and decreases extracellular phosphate levels, promotes the formation of active vitamin D
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what is the action of Vitamin D?
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it stimulates uptake of Ca2+ by the intestines
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what is the function of calcitonin?
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it decreases extracellular Ca2+ levels
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what is the active forms of vitamin D
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it is vitamin D3
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what does vitamin D stimulate?
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synthesis of Ca2+ binding protein in intestinal cells (maintains) Ca+ gradient, Ca-ATPase to pump it out of cells into capillaries
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what are the symptons of hypercalcemia?
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NS and neuromuscular reflexes are hyporeflexia, decreased muscle activity-lethargy, decreased QT interval, constipation, lack of appetitie, CaPO4 starts to precipitate at high Ca levels
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what are the symptoms of hypocalcemia?
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NS excitement, increased membrane permeability to Na+, depolarizing membrane to threshold, hyperreflexia, spontaneous twitching, muscle cramps, over-excitation may result in tetany, Chvostek sign, Trousseau sign
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what is the Chvostek sign?
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twitching of facial muscles elicited by tapping on facial nerve
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what is Trousseau sign?
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carpopedal spasm upon inflation of a blood pressure cuff
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what is the cause of hypophosphatemia?
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reduced absorption from the intestine associated w/ Vit. D deficiency and alcohol abuse
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what are the symtoms of hypophosphatemia?
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reduced rate of metabolism, reduced O2 transport, WBC function and blood clotting
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what are the causes of hyperphosphatemia?
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renal failure, tissue destruction w/ chemotherapy used to treat metastatic tumors, hyperparathyroidism (initially leads to inc. plamsa Ca2+ combined w/ reduced excretion of phosphate by the kidneys
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what are the symptoms of hyperphosphatemia?
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related to reduced plasma Ca2+ conc. due to CaPO4 deposited in tissues such as lungs, kidneys, & joints
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under normal circumstances, how are high levels of phosphate regulated?
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Blood Phosphate inc.-->PO4 levels exceed ability of kidneys to reabsorb from filtrate-->PO4 ions remain in filtrate-->eliminated in urine
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under normal circumstances, how are low levels of Phosphate regulated?
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Blood PO4- levels decrease-->PO4 ions decrease-->efficiency of phosphate ion reabsorption from filtrate in kidney inc.-->inc. PO4 ion reabsorption dec. phosphate ion loss in urine-->PO4 ion levels increase
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what do people w/ hyperparathyroidsim have?
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stones, bones and groans
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what is hypercalciurea?
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it is defined as excessive urinary excretion of calcium, more than 250mg per day in women and 275-300mg per day in men
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