Pharmacology deals with the elucidation of atomic and organismal function in relation to chemicals .
Pharmacology is the branch of biology concerned with the study of drug action , where a drug can be broadly defined as any man-made , natural , or endogenous -LRB- from within body -RRB- molecule which exerts a biochemical or physiological effect on the cell , tissue , organ , or organism -LRB- sometimes the word pharmacon is used as a term to encompass these endogenous and exogenous bioactive species -RRB- .