How Drugs Get into the Brain
Essentially, drugs constitute of chemicals (Brick & Erickson, 1999). When an individual takes drugs, the body absorbs the chemical substance of the drugs into the bloodstream. In the bloodstream, the circulating blood takes the chemical component of the drugs into the brain where they exert their effect.
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The effect of a drug therefore depends on the amount of active ingredient of the drug that is absorbed into the bloodstream and reaches the brain (Brick & Erickson, 1999). In consequence, the amount of drug that an individual takes determines the effect.
For instance, at a very low dose the effects of a drug may not be realized. Once a certain level of concentration of drugs in the bloodstream is reached, the effect is realized. The point at which a drug starts to have effect on the body is known as its threshold.
Beyond the threshold, the effect of a drug increases with increase in active ingredient of the drug in the bloodstream. The effect however does not increase infinitely but reach a maximum point. At very high doses however, the effects of drugs can be extreme or even fatal.
As aforementioned, drugs reach the brain through the bloodstream. The amount and the rate at which drugs get into the bloodstream therefore impact on their effects. Besides the dose, the effect of a drug in depended on how it gets into the body. The common ways in which people take drugs include smoking (inhalation), snorting, injection and orally (Brick & Erickson, 1999).
The effects of drugs that are inhaled or injected into the body are realized quickly. When inhaled, the lungs absorb the active ingredient of a drug and take it directly to the heart. Once in the heart, a drug then gets into the bloodstream and travels to the brain. Similarly, drugs that are injected intravenously get directly into the bloodstream and their effects can be realized in a short time.
On the other hand, drugs that are taken by snorting and oral ingestion are absorbed through the mucous membranes, and the stomach and intestine, respectively. As a result, drugs that are inhaled or taken orally get into the bloodstream slowly and their effects are a bit slow.
Effect of Drugs on Brain Chemistry
Once in the body, drugs interfere with how the brain normally works. Almost all drugs of abuse such as Cocaine and Marijuana target the reward system of the brain (Brick & Erickson, 1999). Drugs bring about their effects by influencing release and absorption of neurotransmitters, especially dopamine.
As a result, drugs affect communication between neurons by influencing the level of dopamine (Hanson, Venturelli & Fleckenstein, 2006). Such drugs as nicotine, alcohol and heroin cause release of more dopamine in synapse part of the brain by motivating more action potentials within Ventral Tegmental Area. Other drugs such as crank and methamphetamine stimulate release of dopamine independent of action potentials.
As aforementioned, drugs interfere with normal working of the reward system in the brain. Under normal circumstances, reward circuit release dopamine in response to pleasurable experience (Hanson, Venturelli & Fleckenstein, 2006).
The dopamine neurotransmitter triggers the brain to pay attention and remember pleasurable experiences. When a drug gets into the brain, it interferes with the normal working of the system and cause high level of dopamine. The high level of dopamine then leads to the euphoric pleasure that is associated with drugs of abuse.
Brick, J. & Erickson, C. (1999). Drugs, the brain, and behavior: the pharmacology of abuse and dependence. New York: Routledge.
Hanson, G., Venturelli, P. & Fleckenstein, A. (2006). Drugs and society. Sudbury: Jones & Bartlett Learning.