Pot, weed, grass, and many others
The most commonly used illegal drug in North America. The main active chemical is THC (delta-9-tetrahydrocannabinol). It is dry, shredded green/brown mix of flowers, stems, seeds, and leaves of the hemp plant Cannabis sativa. It usually is smoked as a cigarette (joint, nail), or in a pipe (bong). It also is smoked in blunts, which are cigars that have been emptied of tobacco and refilled with marijuana, often in combination with another drug. It might 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.
In the brain, THC connects to specific sites called cannabinoid receptors. Many cannabinoid receptors are found in the parts of the brain that influence pleasure, memory, thought, concentration, sensory and time perception, and coordinated movement. The short-term effects of marijuana can include problems with memory and learning, distorted perception, difficulty in thinking and problem solving, loss of coordination, and increased heart rate. Long-term marijuana abuse indicates some changes in the brain similar to those seen after long-term abuse of other major drugs. One study has indicated that an abuser’s risk of heart attack more than quadruples in the first hour after smoking marijuana. Regular marijuana smokers may have many of the same respiratory problems that tobacco smokers do, such as daily cough and phlegm production, more frequent acute chest illness, increase risk of lung infections, and a greater tendency to obstructed airways. Smoking marijuana possibly increases the likelihood of developing cancer of the head, neck and lungs.