Cannabis

Cannabis, also known as marijuana, marihuana, and ganja (from Sanskrit: गांजा gañjā, meaning "hemp"), among many other names, refers to any number of preparations of the Cannabis plant intended for use as a psychoactive drug. The most common form of cannabis used as a drug is the dried herbal form.
The typical herbal form of cannabis consists of the flowers and subtending leaves and stalks ofmature pistillate or female plants. The resinous form of the drug is known as hashish (or merely as 'hash').
Cannabis use has been found to have occurred as long ago as the third millennium B.C. In modern times, the drug has been used for recreational, religious or spiritual, and medicinal purposes. The United Nations (UN) estimated that in 2004 about 4% of the world's adult population (162million people) use cannabis annually, and about 0.6% (22.5 million) use it on a daily basis. The possession, use, or sale of cannabis preparations containing psychoactive cannabinoids became illegal in most parts of the world in the early twentieth century. Since then, some countries have intensified the enforcement of cannabis prohibition, while others have reduced it.
Marijuana is the most commonlyabused illicit drug in the United States. It is a dry, shredded green and brown mix of flowers, stems, seeds, and leaves. The main active chemical in marijuana is delta-9-tetrahydrocannabinol; THC for short.
How is Marijuana Abused?
Marijuana is usually smoked as a cigarette (joint) or in a pipe. It is also smoked in blunts, which are cigars that have been emptied of tobacco and refilled withmarijuana. Since the blunt retains the tobacco leaf used to wrap the cigar, this mode of delivery combines marijuana's active ingredients with nicotine and other harmful chemicals. Marijuana can also be mixed in food or brewed as a tea. As a more concentrated, resinous form it is called hashish, and as a sticky black liquid, hash oil. Marijuana smoke has a pungent and distinctive, usuallysweet-and-sour odor.
How Does Marijuana Affect the Brain?
Scientists have learned a great deal about how THC acts in the brain to produce its many effects. When someone smokes marijuana, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to the brain and other organs throughout the body.
THC acts upon specific sites in the brain, called cannabinoid receptors, kicking offa series of cellular reactions that ultimately lead to the “high” that users experience when they smoke marijuana. Some brain areas have many cannabinoid receptors; others have few or none. The highest density of cannabinoid receptors are found in parts of the brain that influence pleasure, memory, thoughts, concentration, sensory and time perception, and coordinated movement.
Not surprisingly,marijuana intoxication can cause distorted perceptions, impaired coordination, difficulty in thinking and problem solving, and problems with learning and memory. Research has shown that marijuana’s adverse impact on learning and memory can last for days or weeks after the acute effects of the drug wear off. As a result, someone who smokes marijuana every day may be functioning at a suboptimalintellectual level all of the time.
Research on the long-term effects of marijuana abuse indicates some changes in the brain similar to those seen after long-term abuse of other major drugs. For example, cannabinoid withdrawal in chronically exposed animals leads to an increase in the activation of the stress-response system and changes in the activity of nerve cells containing dopamine. Dopamineneurons are involved in the regulation of motivation and reward, and are directly or indirectly affected by all drugs of abuse.
Addictive Potential
Long-term marijuana abuse can lead to addiction; that is, compulsive drug seeking and abuse despite its known harmful effects upon social functioning in the context of family, school, work, and recreational activities. Long-term marijuana abusers...