kidney tries to dump excess calcium and in the process also excretes excess water.
excess calcium binds to oxalate and forms stones
slower or absent reflexes
confusion, hallucinations, stupor.
slower muscle contraction = constipation and muscle weakness.
prolongued QT interval, osborne wave, bradycardia and AV block.
Bones and joint
gout and psuedogout and bone pain
increased osteoclastic resorption
excess vitamin D from diet and supps
thiazide diuretics, resorption in the DCT
decrease calcium with IV saline to increase sodium.
inhibit calcium resorption resulting in all calcium being excreted.
inhibit GIT absorption of ca.
prevent bone resorption, by inhibiting osteoclasts.
distribution of calcium
when extracellular calcium is low
release calcium into the blood
resorbs calcium in the DCT
in response to Calcitriol increases absorption of calcium from the diet.
neuronal action, all muscle contraction, hormone secretion and blood regulation
normal in small amounts, electrically neutral not used for processes
non-diffusable: bound to albumin
bound to albumin and not involved in cellular processes, cannot cross cell wall.
albumin is net neg charge. balanced COO- and COOH. changes with bodily acidity
many protons, bind to free COO- and become COOH and becomes positively charged. +ve ca2+ cannot bind as they repel eachother, results in
increased ionised calcium
causes psuedohypocalcaemia because of a resultant increase in albumin concentration. free ionised calcium stays the same because of hormonal regulation.
too much intracellular calcium results in apoptosis
calcium resides in organelles like the mitochondria and the Smooth ER.
controlling what enters the cell are voltage gated and ligand gated channels. to get Ca out are Na+Ca++ exchangers and ATP-CA pumps. responsible for maintaining intracellular calcium for electrical membrane potential.
the role of calcium in the cell
is to stabilise the resting state of the sodium channels on the cell membranes. which prevents the cell from spontaneously depolarising.
high levels of extracellular calcium = sodium channels less likely to open. sodium cannot enter the cell. cell cannot depolarise
results in neurons being less excitable and harder to reach depolarisation
PHT, Vitamin D, albumin, phosphorus, magnesium