Marijuana

Marijuana - often-called pot, grass, reefer, weed, herb, Mary Jane, or mj - is a greenish-gray mixture of the dried, shredded leaves, stems, seeds, and flowers of Cannabis sativa, the hemp plant. Most users smoke marijuana in hand-rolled cigarettes called joints, among other names; some use pipes or water pipes called bongs. Marijuana cigars called blunts have also become popular.

Marijuana is produced in all 50 states, and the primary foreign sources for marijuana found in the United States are Mexico, Canada, Colombia, and Jamaica.

The marijuana plant grows quickly in many environments and can reach a height of 20 feet. The leaves consist of five or more narrow leaflets, each radiating from a slender stem attached to a thick and hallow stalk.

In ancient times cannabis or hemp plant, also called "Marijuana", produced fibers used to make pipe, cloth, roofing materials and floor covering.

The major active chemical in marijuana is delta-9-tetrahydrocannabinol (THC), which causes the mind-altering effects of marijuana intoxication. The amount of THC determines the potency and, therefore, the effects of marijuana.

Effects

Marijuana's effects begin immediately after the drug enters the brain and last from 1 to 3 hours. If marijuana is consumed in food or drink, the short-term effects begin more slowly, usually in Ð'Ð... to 1 hour, and last longer, for as long as 4 hours. Smoking marijuana deposits several times more THC into the blood than does eating or drinking the drug.

Within a few minutes after inhaling marijuana smoke, an individual's heart begins beating more rapidly, the bronchial passages relax and enlarge, and blood vessels in the eyes expand, making the eyes look red. The heart rate, normally 70 to 80 beats per minute, may increase by 20 to 50 beats per minute or, in some cases, even

double. This effect can be greater if other drugs are taken with marijuana. As THC enters the brain, it causes a user to feel euphoric - or "high" - by acting in the brain's reward system, areas of the brain that respond to stimuli such as food and drink as well as most drugs of abuse. THC activates the reward system in the same way that nearly all drugs of abuse do, by stimulating brain cells to release the chemical dopamine.

A marijuana user may experience pleasant sensations, colors and sounds may seem more intense, and time appears to pass very slowly. The user's mouth feels dry, and he or she may suddenly become very hungry and thirsty. His or her hands may tremble and grow cold. The euphoria passes after awhile, and then the user may feel sleepy or depressed. Occasionally, marijuana use produces anxiety, fear, distrust, or panic. Marijuana use impairs a person's ability to form memories, recall events, and shift attention from one thing to another. THC also disrupts coordination and balance by binding parts of the brain that regulate balance, posture, coordination of movement, and reaction time.

Effects on the Brain

When someone smokes marijuana, THC rapidly passes from the lungs into the bloodstream, which carries the chemical to organs throughout the body, including the brain. In the brain, THC connects to specific sites called cannabinoid receptors on nerve cells and influences the activity of those cells. Many cannabinoid receptors are found in the parts of the brain that influence pleasure, memory, thought, concentration, sensory and time perception, and coordinated movement.

Effects on the Heart

One study has indicated that a user's risk of heart attack more than quadruples in the first hour after smoking marijuana. The researchers suggest that such an effect might occur from marijuana's effects on blood pressure and heart rate and reduced oxygen-carrying capacity of blood.

Effects on the Lungs.

Someone who smokes marijuana regularly may have many of the same respiratory problems that tobacco smokers do, such as daily cough and phlegm production, more frequent acute chest illness, a heightened risk of lung infections, and a greater tendency to obstructed airways.

Cancer of the respiratory tract and lungs may also be promoted by marijuana smoke. Marijuana use has the potential to promote cancer of the lungs and other parts of the respiratory tract because it contains irritants and carcinogens. In fact, marijuana smoke contains 50 to 70 percent more carcinogenic hydrocarbons than does tobacco smoke and produces high levels of an enzyme that converts certain hydrocarbons into their carcinogenic formÐ'--levels that may accelerate the changes that ultimately produce malignant cells.

Other Health Effects

Some of marijuana's adverse health effects may occur because THC impairs the immune system's ability to fight off infectious diseases and cancer.

Effects of Heavy Marijuana Use on Learning and Social Behavior

Depression, anxiety, and personality disturbances are all associated with marijuana use. . Because marijuana compromises the ability to learn and remember information, the more a person uses marijuana the more he or she is likely to fall behind in accumulating intellectual, job, or social skills.

Students who smoke marijuana get lower grades and are less likely to graduate from high school, compared to their non-smoking peers.

Short-term effects

Ð'* Impairs short-term memory

Ð'* Impairs attention, judgment, and other cognitive functions

Ð'* Impairs coordination and balance

Ð'* Increases heart rate

Ð'* Increases pleasure

Long-term effects

Ð'* Can lead to addiction

Ð'* Increases risk of chronic cough, bronchitis, and emphysema

Ð'* Increases risk of cancer of the head, neck, and lungs

Addictive Potential

Long-term marijuana use can lead to addiction for some people; that is, they use the drug compulsively even though it often interferes with family, school, work, and recreational activities. Drug craving and withdrawal