Marijuana Marijuana is a green or gray mixture of dried, shredded flowers and leaves of the hemp plant Cannabis sativa . In recent years, marijuana has appeared in blunts, which are cigars that have been emptied of tobacco and refilled with marijuana, often in combination with another drug, such as crack.
Some users also mix marijuana into foods or use it to brew tea.
Once securely in place, THC kicks off a series of cellular reactions that ultimately lead to the high that users experience when they smoke marijuana. Scientists have found that whether an individual has positive or negative sensations after smoking marijuana can be influenced by heredity. A recent study demonstrated that identical male twins were more likely than non-identical male twins to report similar responses to marijuana use, indicating a genetic basis for their sensations. Effects of Marijuana on the Brain Researchers have found that THC changes the way in which sensory information gets into and is processed by the hippocampus. The hippocampus is a component of the brain's limbic system that is crucial for learning, memory, and the integration of sensory experiences with emotions and motivations.