Полнотекстовый поиск:
Где искать:
только в названии
только в тексте
слова в тексте
только заголовок

Рекомендуем ознакомиться

Остальные работы->Реферат
Norce Farmers in GreenlandReviewBuckland, P.C., Amorosi, T., Barlow, L.K., Dugmore, A.J., Mayewski, P.A., McGovern, T.H.,Ogilvie, A.E.J., Sadler, J.P....полностью>>
Остальные работы->Реферат
Lolita is one of the most unconventional literary classics of the century. Lolita is a twelve-year-old girl, who is desired by the European intellectu...полностью>>
Остальные работы->Реферат
This ment that a person no longer had to reload a gun or waste time re-aiming the gun. Each machine-gun had the fire power of 100 rifles, and were man...полностью>>
Остальные работы->Реферат
For the last few decades we can all admit that Television has been used as a source of mass medium exposure to the public masses. Television has been ...полностью>>

Главная > Реферат >Остальные работы

Сохрани ссылку в одной из сетей:

Marijuna Essay, Research Paper

Marijuana, the crude drug made from the leaves and flowering tops of the cannabis sativa plant, contains hundreds of active chemicals. Of the 421 chemicals identified in the plant, 70 are cannabinoids (chemicals found only in the marijuana plant and nowhere else in nature). Cannabinoids are stored in the fat parts of cell membranes for long periods of time and interfere with normal cell functioning. Since the 70 annabinoids are fat-soluble, they build up or accumulate in body tissue. Three to seven days after using marijuana, a 50 percent level of biochemical activity will remain in the cells. It takes the body 20 to 30 days to metabolize or wash out the chemicals from the marijuana. Some clinicians feel that it may take as much as six to 12 weeks of no marijuana use for the long-term heavy user to become free from the drug.

In one respect, marijuana is similar to DDT and other pesticides, which are also fat-soluble and build up in human tissue. The marijuana plant is a complex and unpredictable chemical factory. The amount of THC (the major mind-altering chemical in marijuana) produced in the plant leaves and flowering tops will vary from plant to plant, even within the same plant, and from hour to hour. The marijuana used in the 1960s was quite low in THC content, ranging from .25 percent to one percent. Few health hazards were noted during that period. In the 1970s, the Mexican marijuana coming into the country averaged one percent to two percent THC. The Mexican variety became the standard research material. When research scientists tried to use marijuana that had THC levels over two percent, they found too many side effects to feel safe in using it with human subjects. After 1976, Colombian marijuana became prominent. It ranged from three percent to five percent in THC. Presently, we have marijuana being grown in the United States that exceeds 20 percent THC levels. An example of this is the Sinsemilla variety produced in several states. Because today’s marijuana is stronger than that of the ’60s due to the higher levels of THC now available, the studies done with standard two percent THC marijuana will need to be redone usingtoday’s more potent form if we are to understand the health effects caused by marijuana use during the ’80s and ’90s.

Hashish, which is produced from the resin of the marijuana plant, has a slightly different chemical composition. The THC levels in hashish will vary from two percent to 20 percent. Other biologically active chemicals appear in higher concentrations than in the unaltered marijuana. Hashish also burns at a much higher temperature than marijuana. This higher temperature may explain the very early tissue damage seen in the young hashish smoker. Hashish oil is a thick, black, oily substance which is obtained by the further refinement of hashish. The THC level in “hash oil” may reach 30 percent and can produce intense hallucinations. Since the hash oil does not contain sugars found in the plant material, it will not have the familiar “sweet” marijuana smell when burned. Hash oil, being quite high in THC content, is very disorienting and dangerous.

Even under the very best research conditions, the chemical content of street marijuana is unknown. This leaves both researcher and user in doubt as to what chemicals actually enter the body. The complexity and unpredictability of marijuana makes controlled, scientific experimentation a slow, tedious and sometimes contradictory process.

Marijuana refers to the dried leaves and flowers of the cannabis sative plant that contains the psychoactive chemical THC (delta-9-tetrahydrocannabinol) at various potencies. Most hemp plants have an average of 3% THC in them, as well as over four hundred other chemicals. THC is strongly absorbed by fatty tissues in different organs, and traces of it can be detected by standard urine tests for several days following usage, even weeks in heavy users. As for the effect that THC has on the brain, it suppresses neurons in the information processing system of the hippocampus, the part of the brain that is crucial for learning, memory, and the integration of sensory experiences with emotions and motivation. Many marijuana smokers believe that their senses are heightened by the drug. In fact, the brain is dulled, not enhanced. Marijuana usage can thus result in problems with memory and learning, distorted perception, loss of coordination, and trouble with thinking and problem-solving. However, the effects of the drug are dependent on the user’s experience, how much THC is in the marijuana, how the drug is taken, and whether it is taken with other drugs or alcohol. More obvious effects of the drug are a dry mouth, increase in heartbeat, slow reaction time, and the blood vessels in the eyes expand. The air tubing in the lungs relax and become larger as more oxygen enters the blood. Most users will experience feelings of relaxation, a “high”, hunger and thirst, while others may have a more negative response through feelings of anxiety or paranoia. A recent scientific study has shown that THC causes certain types of white blood cells to stop growing in mid-cycle, meaning that heavy marijuana smokers are more susceptible to infection. Although THC is a mind-altering chemical, scientists have not found an amount that is toxic. Primarily due to this fact, there has never been a case in which marijuana alone has caused death.

Marijuana is typically smoked or eaten for pleasure, but THC is also found in a manufactured pill form for medical purposes. It is used to help treat nausea and vomiting that occurs with certain cancer treatments, as well as to help AIDS patients eat more and keep up their weight.

THC (delta-9-tetrahydrocannabinol) and the other cannabinoids are fat-soluble chemicals. They accumulate in the fatty linings of the cells in the body and are metabolized or “washed out” of the system very slowly. A week after a person smokes one marijuana cigarette, 30 to 50 percent of the initial fat-soluble chemical deposited from marijuana smoking remains in the body; it is estimated that four to six weeks are required to eliminate all the marijuana chemicals. Thus, those who smoke only on the weekends gradually increase the level of THC in their body. Regular use — even once or

twice a week — means the user is never free of the drug. The persistence of THC in the cells of the body differentiates marijuana from alcohol. Alcohol is a water-soluble hemical that is metabolized or “washed-out” of the body relatively quickly. Thus, the

youngster who drinks too much will probably get sick and suffer a hangover the next day, as the stomach and liver process the alcohol. This detoxification is completed within 12 to 24 hours. Because THC is not water-soluble, it is not quickly washed out by the body. Many observers of youthful marijuana smokers worry that this slow, subtle accumulation within the body, and especially the brain, seems to cause gradual personality and behavioral changes. Youngsters who are undergoing rapid and complex changes in body chemistry and emotional development may be more susceptible to the accumulation of THC and other chemicals than adults.Many marijuana users believe the widespread street myth that users do not risk physical addiction. They are unaware of recent studies verifying that users of marijuana develop a tolerance to the drug. Heavy users require increasing quantities of marijuana (more joints or more THC content) to achieve the same high. Marijuana should be classified as an addictive drug like heroin or cocaine since recent studies show that heavy, long-term use may cause strong dependency in users as they increase their dosage to satisfy higher tolerance levels. Furthermore, new surveys find tobacco-like use patterns in some users as marijuana becomes easier and cheaper to obtain. Reporters for NBC’s television documentary, Reading, Writing, and Reefer, were surprised to learn that some youngsters nine to 15-years-old are smoking five to 10 marijuana cigarettes a day. Increasing potency also creates more rapid and serious dependency, meaning that currently available marijuana must be considered an addictive drug. Increasing numbers of teenagers report getting “very” intoxicated or “bombed” when they smoke marijuana, suggesting they may be using a powerful form of the drug. Among teens who smoked in the last month, nearly 20 percent reported compulsive daily use. Dr. Charles Schuster, former director of the National Institute on Drug Abuse (NIDA), stated: “Physical dependence, which is what most people mean by addiction, has been scientifically demonstrated. The abstinence syndrome, (the indicator of physical dependence) can occur when a state of marijuana intoxication is maintained over a prolonged period of time and then abruptly discontinued. Anorexia, anxiety, agitation, depression, restlessness, irritability, tremors, severe insomnia, sweating, exaggerated deep tendon reflexes, tremulousness of the tongue and extremities, and dysphoria have all been observed when marijuana use is rapidly withdrawn. It is important to note that these effects occur after only a few weeks of constant use and at dosages that would be common among street users.”Marijuana does not produce the same kind of hangover that alcohol does. While the after-effects of marijuana use are not usually dramatic, they still exist. Because the fat-soluble cannabinoids are washed out of the cell slowly (20 to 30 days), marijuana withdrawal occurs over a longer period of time with less dramatic symptoms. Alcohol is water soluble, and the ethanol is washed out in 12 to 24 hours causing more pain, headache, etc. Young adolescent users occasionally report withdrawal symptoms, and parents and pediatricians should be aware that a temporary flu-like syndrome may occur when a youngster stops using marijuana.

How do the chemicals in marijuana change the way a person sees,hears, smells, tastes, and feels things? When someone uses marijuana, these chemicals travel through the bloodstream and quickly attach to special places on the brain’s nerve

cells. These places are called receptors, because they receive information from other nerve cells and from chemicals. When a receptor receives information, it causes changes in the nerve cell. The chemical in marijuana that has a big impact on the brain is called THC — tetrahydrocannabinol. Scientists recently discovered that some areas of the brain have a lot of THC receptors, while others have very few or none. These clues are helping researchers figure out exactly how THC works in the brain. Some of THC’s effects are useful in the world

of medicine — like preventing nausea and blocking pain. The trick is for scientists to get these results without the harmful effects. Researchers recently found out the brain makes a chemical — anandamide ? that attaches to the same receptors as THC. This discovery may lead to the development of

medications that are chemically similar to THC but less harmful, and they may be used for treating nausea and pain. Due to restraints on experiments in which marijuana is used on human subjects, especially on the female who may become pregnant, most of our information comes from animal studies and healthy males. Since marijuana was seldom used by the female in ancient cultures, there is little information that can be drawn from historical data. However, current research is reporting effects of marijuana use on females during pregnancy. The recent research is raising serious concerns about the effect on female reproductive health. This new information, along with research on animals, helps us better understand the harmful effects of marijuana. Marijuana acts on the part of the brain (the hypothalamus) which directs the signals that regulate hormones. In turn, this determines the sequence in the menstrual cycle. Scientists have found that marijuana interferes with the hormone signals, which can cause irregular or absent ovulation. In the only clinical study reported on human females, the menstrual cycles were irregular, the female hormones were depressed, and the testosterone level was raised. In animal studies and in clinical reports, a complete cessation of menstruation is sometimes found in heavy users. Even though this

effect may be reversible, it may take several months of no marijuana use before the menstrual cycles become normal again. Researchers are particularly concerned about marijuana use by adolescent girls, whose reproductive systems are in a fragile and complex period of development. A disruption or decrease of sex hormones in the developing and immature body of the young female may have longer lasting or even permanent effects. In both animal and human studies, marijuana has been shown to have negative effects on pregnancy. We know that the chemicals in marijuana are transported to the developing fetus through the

placenta. There seems to be a disruption of the placenta function, which may explain the increase in miscarriages, stillbirths and deaths soon after birth.

Visible birth defects, such as limb malformations, have not been reported in humans. Recent clinical studies of newborns born to mothers who were marijuana smokers show subtle defects in the central nervous system. These babies show abnormal reactions to light and sound, exhibit tremors and startles, and have the high-pitched cry associated with drug withdrawal. Scientists are concerned about the long-term effects of marijuana on the unborn child. Occurring at five times the rate of Fetal Alcohol Syndrome, Fetal Marijuana Syndrome is a growing concern of many doctors. Concern that maternal marijuana use during pregnancy may be linked with nonlymphoblastic leukemia in children is also rising. Furthermore, doctors worry that children born to marijuana-using mothers will have learning disabilities, attention deficits and hormonal irregularities as they grow older, even if there are no apparent signs of damage at birth. Pregnant or nursing mothers who smoke marijuana should talk to their doctors immediately. Studies consistently show that marijuana interferes with growth and reproductive hormones. This is of particular significance to developing adolescents who are going through a very vulnerable period of rapid and complex biochemical changes. In the U.S., as in most countries, marijuana experiments on adolescents are not allowed; therefore, most of our scientific knowledge about marijuana’s effect on the growth process and sexual development of our youth is based on animal research and research on the adult male. The chemicals in marijuana affect the parts of the brain which control and regulate the sex and growth hormones. In males, marijuana can decrease the testosterone level. Testosterone is a major growth hormone and is essential to the completion of the growth process in young males. This process, including the broadening of shoulders, enlargement of muscles in the chest, biceps, and buttocks, deepening of the voice, beard growth and genital development, is dependent on adequate hormone levels. For a long time parents and physicians have described the typical male “pot head” as having narrow shoulders, lack of muscle development (particularly in upper arms, chest, buttocks and upper leg),

pale looking face and heavy-lidded eyes. Pediatricians and endocrinologists report increasing cases of pubertal arrest which seem to be marijuana- related.

The occasional cases of enlarged breasts in male marijuana users seem to be triggered by the chemical impact on the hormone system. Regular marijuana use is also associated with a decrease in sperm count and sperm motility, as well as significant increases in abnormal and immature sperm. In many of the sperm, the transmission of DNA is altered and chromosomes are rearranged. Recent animal studies have raised serious concerns that chromosomal aberrations and genetic mutations may be transmitted from the father to the next generation of male offspring. Marijuana is a contributing factor in the rising problem of infertility in males. Young males should know the effects and potential effects of marijuana use on sex and growth processes.


Загрузить файл

Похожие страницы:

  1. Ecstasy Essay Research Paper In the year

    Реферат >> Остальные работы
    Ecstasy Essay, Research Paper In the year 1998, there were approximately 1.2 ... , Ecstasy, just second to marijuana, is the most commonly used drug among ... ravers today what marijuana did for the hippies. The common creed for all ravers ...
  2. Affirmative Action Essay Research Paper I The

    Реферат >> Остальные работы
    ... Action Essay, Research Paper I. The History of Diversity in America Known as the ?Melting ... Bakke and the recent ruling by the U.S. Court of Appeals for the Fifth Circuit ... Americans?. American Demographics. March 1997. Myerson, Allen R. ?Supermarket Chain To ...
  3. Death Penalty Essay Research Paper Whenever the

    Реферат >> Остальные работы
    Death Penalty Essay, Research Paper Whenever the word “death penalty” comes up, ... many studies such as Markman and Cassal, found the study’s methodology so ... crimes. In McClesky v. Zant, the court ruled that the death penalty was not ...
  4. Porography Essay Research Paper In the late

    Реферат >> Остальные работы
    ... Essay, Research Paper In the late seventies, Our Nation became shocked and outraged by the ... what pornography means.A Supreme Court Judge is quoted as ... in this matter since the federal court of Canada passed a ... death (Itzin 26). Ms Marchiano did escape and when ...
  5. Animal Farm Essay Research Paper SETTING The

    Реферат >> Остальные работы
    Animal Farm Essay, Research Paper SETTING The novel is set in Hertfordshire, ... on Major’s teachings, Marxism, and the Communist Manifesto. The second chapter also describes ... the crowd of animals, he gives a high-pitched whimper, and the dogs attack the crowd ...

Хочу больше похожих работ...

Generated in 0.001384973526001