Читать книгу An Introduction to Testing for Drugs of Abuse - William E. Schreiber - Страница 13

Small amounts of a drug can have potent effects on the body. In most cases, those effects are mediated through binding of the drug to receptors that control cellular processes.

Drugs that affect the central nervous system act on neurons to increase or decrease the transmission of nerve impulses. Some drugs affect the flow of ions into and out of neurons, which changes their ability to initiate or propagate an action potential. Other drugs affect the release and reuptake of neurotransmitters, thereby stimulating or inhibiting communication between individual neurons.

Any drug can be used inappropriately. However, certain drugs are more prone to misuse than others because of their mood‐altering or intoxicating effects. These drugs activate the brain's reward system by stimulating the release of dopamine in several pathways. The sense of euphoria they produce is accompanied by other effects – feelings of energy and power in the case of stimulants, or relaxation and peace in the case of opioids.