Heroin is an illegal, highly addictive drug processed from morphine, a naturally occurring substance extracted from the seed pod of certain varieties of poppy plants. Heroin usually appears as a white or brown powder or as a black sticky substance, known as black tar heroin. Heroin is used by either intravenous injection, snorted, or smoked. Common street names for heroin include; Black Tar, Norse, Smack Thunder and Dust. Heroin enters the brain and is converted back into morphine which binds rapidly to the opioid receptors in the brain. These receptors control both the pleasure and pain sensations and our automatic processes such as breathing and arousal. The short term effects of heroin use include, feelings of a rush, clouded mental functioning, depressed respiration, nausea and vomiting. Long term effects include addiction, abscesses, infectious diseases (HIV, Hepatitis B and C) and liver and kidney diseases. Signs of a heroin overdose are shallow breathing, blue lips and fingernails, clammy skin, convulsions, coma and possible death.