Phosphorus is most abundantly seen in the body as a
constituent of the molecule phosphate, one of the bone salts which add
structural rigidity to the softer protein matrix of bone and teeth.
Perhaps phosphorus most important metabolic role is
as a constituent of the molecule phosphate. When this molecule links to an
adenosine pyrophosphoric acid (ADP) molecule adenosine triphosphate (ATP) is
formed, processing a high energy phosphate bond. When broken, this bond
releases energy and the phosphate, reforming and ADP molecule. The ATP "energy"
molecule is formed during glycolysis and other processes involving the release
of chemical energy from food. ATP is used as the primary source of energy for
many metabolic and enzymatic activities, especially muscle contraction, active
transport, and the formation of DNA. Phosphate is an important constituent of
RNA and DNA. It serves to link the individual bases with one another.
The energy released from the high energy phosphate bond
of ATP is essential for the operation of the sodium/potassium pump, which
exchanges three sodium ions for two potassium ions across a biological
membrane. This pump is used to regulate relative amounts of sodium and
potassium excreted and retained in the body.
Phosphate, from ATP, reacts with choline to initiate
synthesis of phospholipids which are essential constituents of cell membranes.
Phospholipids are instrumental in regulating cellular permeability and are
found in the exterior membrane of nerve cells. They are also helpful in
solubilizing relatively nonsoluble triglycerides and cholesterols.
ADP, which contains two phosphate molecules, is a
constituent of blood platelets and is secreted from platelet granules to
stimulate platelet aggregation for blood clotting.
Phosphate also plays an important role, due to its
effective buffering action, in maintaining acid/base balance in blood
Phosphorus absorption is about 50-70% efficient, as
calcium, iron, and zinc tend to complex with phosphorus in the stomach, thus
reducing absorption. Vitamin D tends to promote the absorption of both
phosphorus and calcium from the intestine. Excretion through the urine
regulated the bodys level of phosphorus.