Exam 5: Calcium Metabolism Flashcards
What is the calcium distribution?
99% bones/teeth
1% intracellular
0.1% extracellular fluid/plasma
What are the different types calcium in extracellular fluid/plasma?
Protein-bound (30-40%)
Ionized (50-60%; unbound)
Complexed
Describe ionized calcium
Biologically active
Fraction dependent on pH
Where is complexed calcium found?
Citrate
Lactate
Bicarbonate
Phosphate
What are the functions of calcium?
Nerve impulses
Muscle contraction
Coagualtion
What does calcium do for nerve impusles
Membrane stabilization
What does calcium do for muscle contraction?
Release of AcCh at NMU
Skeletal
Smooth
Cardiac (ionotropic and chronotropic)
99% of filtered calcium is normally reabsorbed by the renal tubules. 90% of that is reabsorbed in proximal tubules, loops of Henle, and early distal tubules. The remaining 10% is reabsorbed. What is different about this reabsorption?
It is very selective
What are the target tissues of parathyroid hormone?
Bone
Kidney
Small intestine
What does PTH do to bone?
Resorption (release of Ca, P from bone)
Effect on blood levels (increase Ca, increase P)
What does PTH do to kidney?
Reabsorption of Ca (increase Ca)
Excretion of P (decrease P)
What does PTH do to small intestine?
Increase vitamin D3
Increase Ca and P
Where is P excreted from in the kidneys?
Proximal tubules
What is the net effect of PTH on the kidneys?
Increase serum Ca
Decrease serum P
What are the target tissues of calcitriol?
Small intestine
Bone
Parathyroid