Amino Acids and Metabolics
Amino acids are dubbed the building blocks of life. The 23 or so amino acids are the molecular blocks of proteins. According to one accepted classification, 9 are termed indispensable amino acids (IAA, sometimes called essential), meaning that they must be supplied from some food or supplement source; the others, which used to be classified simply as nonessential, are now more correctly termed dispensable amino acids (DAA) or conditionally indispensable, based on the body's ability to synthesize them from other amino acid.
Body Systems 
