Of the well-prefused body organs described above, the liver deserver special mention. This organ is the site for the majority of metabolism within the body, and has the highest concentration of drug-metabolizing enzymes present in the body. The high blood flow to the liver ensures that most chemicals are taken up very efficiently into the liver, thus ensuring their rapid metabolism. While the liver is thought of as the 'seat of metabolism' it should be remembered, hoever, that all tissues in the body have some drug-metabolisme enzymes and are thus capable of some metabolism; the liver merely has the highest concentration and widest variety of these enzymes. As we will see in Chapters 2 and 3, metabolism plays a vital role in both detoxification snd toxication pathways for many chemicals, and hence the liver is a key site for studying chemical toxicity.