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Major Minerals Phosphorus, Magnesium, and Sulfur

Posted by Blog Sunday, March 6, 2011

Phosphorus

Phosphorus is needed in every cell in the body. The name means “lightbearer,” which comes from the Greek word for light, phôs, and the Greek word for bearer, phoros. The chemical symbol for phosphorus is the letter P. About 85 percent of the phosphorus in the body is in the bones. Most of the phosphorus in the body is found in the form of phosphates. Phosphates are the salts of phosphorus. Phosphates are made up of a central phosphorus atom surrounded by four oxygen atoms (PO4), as shown in Figure 10-1.


FUNCTIONS OF PHOSPHORUS IN THE BODY
The main use for phosphorus is strengthening bones. Phosphorus and calcium form  a salt called hydroxyapatite that provides the compressional strength of bones.




Figure 10-1 The structure of phosphate, where R is attached to the phosphate.


Phosphorus in the Cell Membrane
Another important role of phosphorus is as part of the cell membrane. All cell membranes contain phospholipids (phospho from phosphorus and lipids from fats). Phospholipids are major structural components of cell membranes, as seen in Figure 10-2. Phospholipids in cell membranes help control the transport of nutrients. The heads of phospholipids are attracted to water, while the tails are repelled by water.


The water-loving heads of these phospholipids face towards the inside of the cell and towards the outside of the cell. The fat-loving tails face toward the inside of the cell membrane. This forms a membrane that is selectively permeable and very flexible. The cell membrane has an interior that is fat soluble while the inside and the outside of the membrane can exist in a watery environment.



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