White blood cells (WBCs), also called leukocytes or leucocytes, are the cells of the immune system that are involved in protecting the body against both infectious disease and foreign invaders. All white blood cells are produced and derived from multipotent cells in the bone marrow known as hematopoietic stem cells.
Nicotine dependence is now recognized as a psychoactive substance dependence disorder (DSM-IV, ICD-10). Under the DSM-IV criteria smokers are classified as dependent if they exhibit impaired control and continue to smoke despite awareness that it exacerbates a medical condition, and if they experience withdrawal symptoms when abstaining from smoking, or if they have a history of unsuccessful attempts at quitting.
The DSM-IV manual is highly regarded around the world and often relied upon as a reliable medical reference in regards to mental disorders, by lawyers and, provided the evidence is introduced through a qualified, expert witness, courts of law. But note these judicial words: The inclusion or lack of inclusion in DSM IV is interesting but not fatal to the finding of mental disorder ... That is because the finding that the condition is a disease of the mind is a legal finding as opposed to a medical finding. 1. In addition to defining each mental disorder, the DSM-IV lists and catalogs mental disorders.