Introduction:
Cannabis is not only the most abused illicit drug in the United States (Gold, Frost-Pineda, & Jacobs, 2004; NIDA, 2010) it is in fact the most abused illegal drug worldwide (UNODC, 2010). In the United States it is a schedule-I substance which means that it is legally considered as having no medical use and it is highly addictive (US DEA, 2010). Doweiko (2009) explains that not all cannabis has abuse potential. He therefore suggests using the common terminology marijuana when referring to cannabis with abuse potential. For the sake of clarity this terminology is used in this paper as well.  buy medical marijuana online

Today, marijuana is at the forefront of international controversy debating the appropriateness of its widespread illegal status. In many Union states it has become legalized for medical purposes. This trend is known as "medical marijuana" and is strongly applauded by advocates while simultaneously loathed harshly by opponents (Dubner, 2007; Nakay, 2007; Van Tuyl, 2007). It is in this context that it was decided to choose the topic of the physical and pharmacological effects of marijuana for the basis of this research article.

What is marijuana?
Marijuana is a plant more correctly called cannabis sativa. As mentioned, some cannabis sativa plants do not have abuse potential and are called hemp. Hemp is used widely for various fiber products including newspaper and artist's canvas. Cannabis sativa with abuse potential is what we call marijuana (Doweiko, 2009). It is interesting to note that although widely studies for many years, there is a lot that researchers still do not know about marijuana. Neuroscientists and biologists know what the effects of marijuana are but they still do not fully understand why (Hazelden, 2005).

Deweiko (2009), Gold, Frost-Pineda, & Jacobs (2004) point out that of approximately four hundred known chemicals found in the cannabis plants, researchers know of over sixty that are thought to have psychoactive effects on the human brain. The most well known and potent of these is ∆-9-tetrahydrocannabinol, or THC. Like Hazelden (2005), Deweiko states that while we know many of the neurophysical effects of THC, the reasons THC produces these effects are unclear.

Neurobiology:
As a psychoactive substance, THC directly affects the central nervous system (CNS). It affects a massive range of neurotransmitters and catalyzes other biochemical and enzymatic activity as well. The CNS is stimulated when the THC activates specific neuroreceptors in the brain causing the various physical and emotional reactions that will be expounded on more specifically further on. The only substances that can activate neurotransmitters are substances that mimic chemicals that the brain produces naturally. The fact that THC stimulates brain function teaches scientists that the brain has natural cannabinoid receptors. It is still unclear why humans have natural cannabinoid receptors and how they work (Hazelden, 2005; Martin, 2004). What we do know is that marijuana will stimulate cannabinoid receptors up to twenty times more actively than any of the body's natural neurotransmitters ever could (Doweiko, 2009).

Perhaps the biggest mystery of all is the relationship between THC and the neurotransmitter serotonin. Serotonin receptors are among the most stimulated by all psychoactive drugs, but most specifically alcohol and nicotine. Independent of marijuana's relationship with the chemical, serotonin is already a little understood neurochemical and its supposed neuroscientific roles of functioning and purpose are still mostly hypothetical (Schuckit & Tapert, 2004). What neuroscientists have found definitively is that marijuana smokers have very high levels of serotonin activity (Hazelden, 2005). I would hypothesize that it may be this relationship between THC and serotonin that explains the "marijuana maintenance program" of achieving abstinence from alcohol and allows marijuana smokers to avoid painful withdrawal symptoms and avoid cravings from alcohol. The efficacy of "marijuana maintenance" for aiding alcohol abstinence is not scientific but is a phenomenon I have personally witnessed with numerous clients.

Interestingly, marijuana mimics so many neurological reactions of other drugs that it is extremely difficult to classify in a specific class. Researchers will place it in any of these categories: psychedelic; hallucinogen; or serotonin inhibitor. It has properties that mimic similar chemical responses as opioids. Other chemical responses mimic stimulants (Ashton, 2001; Gold, Frost-Pineda, & Jacobs, 2004). Hazelden (2005) classifies marijuana in its own special class - cannabinoids. The reason for this confusion is the complexity of the numerous psychoactive properties found within marijuana, both known and unknown. One recent client I saw could not recover from the visual distortions he suffered as a result of pervasive psychedelic use as long as he was still smoking marijuana. This seemed to be as a result of the psychedelic properties found within active cannabis (Ashton, 2001). Although not strong enough to produce these visual distortions on its own, marijuana was strong enough to prevent the brain from healing and recovering.

Emotions:
Cannibinoid receptors are located throughout the brain thus affecting a wide variety of functioning. The most important on the emotional level is the stimulation of the brain's nucleus accumbens perverting the brain's natural reward centers. Another is that of the amygdala which controls one's emotions and fears (Adolphs, Trane, Damasio, & Damaslio, 1995; Van Tuyl, 2007).

I have observed that the heavy marijuana smokers who I work with personally seem to share a commonality of using the drug to manage their anger. This observation has evidenced based consequences and is the basis of much scientific research. Research has in fact found that the relationship between marijuana and managing anger is clinically significant (Eftekhari, Turner, & Larimer, 2004). Anger is a defense mechanism used to guard against emotional consequences of adversity fueled by fear (Cramer, 1998). As stated, fear is a primary function controlled by the amygdala which is heavily stimulated by marijuana use (Adolphs, Trane, Damasio, & Damaslio, 1995; Van Tuyl, 2007).

Neurophysical Effects of THC:
Neurological messages between transmitters and receptors not only control emotions and psychological functioning. It is also how the body controls both volitional and nonvolitional functioning. The cerebellum and the basal ganglia control all bodily movement and coordination. These are two of the most abundantly stimulated areas of the brain that are triggered by marijuana. This explains marijuana's physiological effect causing altered blood pressure (Van Tuyl, 2007), and a weakening of the muscles (Doweiko, 2009). THC ultimately affects all neuromotor activity to some degree (Gold, Frost-Pineda, & Jacobs, 2004).

An interesting phenomena I have witnessed in almost all clients who identify marijuana as their drug of choice is the use of marijuana smoking before eating. This is explained by effects of marijuana on the "CB-1" receptor. The CB-1 receptors in the brain are found heavily in the limbic system, or the nucleolus accumbens, which controls the reward pathways (Martin, 2004). These reward pathways are what affect the appetite and eating habits as part of the body's natural survival instinct, causing us to crave eating food and rewarding us with dopamine when we finally do (Hazeldon, 2005). Martin (2004) makes this connection, pointing out that unique to marijuana users is the stimulation of the CB-1 receptor directly triggering the appetite.

What is high grade and low grade?
A current client of mine explains how he originally smoked up to fifteen joints of "low grade" marijuana daily but eventually switched to "high grade" when the low grade was starting to prove ineffective. In the end, fifteen joints of high grade marijuana were becoming ineffective for him as well. He often failed to get his "high" from that either. This entire process occurred within five years of the client's first ever experience with marijuana. What is high and low grade marijuana, and why would marijuana begin to lose its effects after a while?

The potency of marijuana is measured by the THC content within. As the market on the street becomes more competitive, the potency on the street becomes more pure. This has caused a trend in ever rising potency that responds to demand. One average joint of marijuana smoked today has the equivalent THC potency as ten average joints of marijuana smoked during the 1960's (Hazelden, 2005).