It is the most abundant mineral of animal body.
Calcium is available in all types of vegetables, grain, milk, cheese, eggs, fish and butter.
By its deficiency rickets, tetanus & paget disease is caused.
For absorption of Ca PTH is must.
It helps in -
(a) Formation of bones and teeth.
(b) It is required for exocytosis of endocrine glands.
(c) Transmission between nerves and muscles.
(d) Working of muscles.
(e) Blood clotting.
(f) Membrane permeability.
(g) As constituent of calcium pectate in middle lamella.
(h) As constituent of exoskeleton of many invertebrates and molluscan shells. (i) It acts as activator of some enzymes like ATP-ase, phospholipase, etc.
(j) To control heart beat.