Explain how alcohol acts as a central nervous system depressant.

• A. It slows brain activity.
• B. It speeds up brain activity.
• C. It only affects the liver.
• D. It slows brain activity, reduces coordination and reaction times, and affects neurotransmitter systems (e.g., GABA).

Answer: (D)

Alcohol acts as a central nervous system depressant because it slows brain activity by altering how neurons communicate. It enhances GABA, the brain’s main inhibitory chemical, making neurons less likely to fire, and it dampens glutamate, which normally excites neurons. This combination reduces overall brain processing speed, which shows up as slower thinking and slower reflexes. It also disrupts coordination and reaction times by affecting the brain regions responsible for movement, such as the cerebellum and motor cortex. In short, it slows brain activity, impairs coordination and reaction times, and changes neurotransmitter systems like GABA. The liver metabolizes alcohol, but the immediate effects on the brain come from these neurotransmitter changes, not from the liver alone.