Role | Description |
Metabolic | Coenzyme for coagulation factors |
Neuromuscular | Muscle excitability and contraction Neurotransmitter release |
Structural | Bone and teeth |
Signalling | Intracellular second messenger |
The bone pool of Ca2+ of 25,000mmol has a small component that moves between bone and the ECF regulating Ca2+ homeostasis.
Ionised Ca2+ is filtered through the renal glomeruli into the tubules and most is reabsorbed. In the normal state only 2.5-7.5mmol/24h appears in the urine.
Unless lactating, pregnant or growing, the dietary requirement of Ca2+ is 12.5mmol/24h as faecal losses amount to approximately 10mmol/24h.