Re: WHAT IS CALCIUM, AND ITS FUNCTIONS IN THE HUMAN BODY?

Calcium (symbol: Ca) is one of the alkaline earth metals that comprise the 
Group IIA or S2 elements of the periodic table. The electronic 
configuration of calcium (atomic number: 20) is 1S2;2S22P6;3S23P6;4S2. The 
physical constants of calcium are as follows:
1. Atomic mass : 40.08
2. Atomic radius : 1.74 A0
3. Ionic radius : 0.99 A0
4. Density : 1.60 g/cm3
5. Melting point : 1116 K
6. Ionisation energy (KJ/mol) : I stage 590
                                II stage 1146
7. Electronegativity : 1.04
8. Flame coloration : Brick red
9. Oxidation state : +2
10. Abundance in earth's crust (ppm) : 3.0 x 10(4)

Calcium is extracted by the electrolysis of a fused mixture of anhydrous 
calcium chloride and potassium chloride using iron cathode and graphite 
anode.
Calcium being a powerful reducing agent is used in extraction of metals 
from oxides which are difficult to reduce with carbon. It is also used for 
removing last traces of dissolved oxygen, nitrogen and sulfur from metals 
in the course of their extraction.
Important compounds of calcium are calcium oxide, calcium hydroxide, 
calcium chloride, calcium sulfate (gypsum), and plaster of Paris.

Calcium helps build and maintain strong bones and teeth, thus protecting 
against osteoporosis. It plays a role in nerve conduction, muscle 
contraction and blood clotting. Calcium also appears to regulate blood 
pressure and may help lower the risk for colon cancer.
Calcium helps muscle contraction (including in the heart) by allowing 
proteins found in muscles (called actin and myosin) to interact properly. 
By participating in the synthesis of fibrin, calcium makes it possible for 
blood clots to form.
Calcium affects the release of neurotransmitters.
Calcium regulates cell metabolism, including glycogen synthesis (the 
process by which glucose is converted into glycogen). Calcium can bind free 
fatty acids and bile acids, which irritate the colon. This irritation may 
increase cell development to the point of increasing the risk of cancers.
In adults, osteomalacia and/or osteoporosis (fragile, brittle bones that 
fracture under normal use) can result from calcium deficiency. In addition, 
loss of height and premature tooth loss may exist.
If blood calcium levels are low (hypocalcemia), muscles cannot relax 
following a contraction, resulting in tetany. Symptoms of tetany include 
muscle spasms and leg cramps. In children, the deficiency disease, rickets, 
leads to stunted growth and bone deformities.
The adult body contains approximately 1200g of calcium, ~99% of which is 
present in the skeleton. The remaining 1% of body calcium is found in the 
extracellular fluid, intracellular structures and cell membranes.

Kumar Chandrasekharan
Cellular and Molecular Cardiology
Sree Chitra Tirunal Institute for Medical Sciences and Technology
Trivandrum, Kerala
India 695 011