Alcohol’s effects on the human body, particularly the brain, can be profound. This article explains the scientific mechanisms by which alcohol causes drunkenness.
Alcohol’s Journey Through the Body
After consumption, alcohol does not require digestion like food; it is absorbed directly into the bloodstream. A small amount is absorbed through the lining of the mouth, and reaches the stomach. Approximately 20% of the alcohol is absorbed in the stomach, though this rate can vary.
The majority of alcohol absorption occurs in the small intestine. Once absorbed, alcohol enters the capillaries and then circulates throughout the body. This rapid distribution means alcohol can begin to affect the brain and other systems within minutes of consumption.
How Alcohol Affects the Brain
Alcohol primarily acts as a central nervous system depressant, meaning it slows down brain activity. It achieves this by interacting with specific chemical messengers in the brain called neurotransmitters. One key interaction involves gamma-aminobutyric acid (GABA), the brain’s main inhibitory neurotransmitter.
Alcohol enhances GABA’s effects, essentially increasing the “braking” signals in the brain. This enhancement of GABA leads to a reduction in neuronal excitability, making brain cells less likely to fire signals.
Simultaneously, alcohol suppresses the activity of glutamate, the brain’s primary excitatory neurotransmitter. By decreasing glutamate’s “accelerating” signals, alcohol further contributes to the overall slowdown of brain function. These combined effects impact several brain regions.
The prefrontal cortex, responsible for judgment and decision-making, experiences impaired function, leading to reduced inhibitions. The cerebellum, which controls coordination and balance, is also affected, resulting in unsteadiness. Additionally, the hippocampus, crucial for memory formation, can be disrupted, potentially causing memory gaps or “blackouts.”
Recognizing the Signs of Intoxication
The biological effects of alcohol on the brain manifest as observable physical and cognitive changes. As brain activity slows, individuals may exhibit slurred speech, impaired motor control, and an unsteady gait. Cognitive functions decline, resulting in altered judgment, confusion, and reduced attention. Emotional responses can become unpredictable, with changes in mood and reduced inhibitions. In more severe cases, memory impairment, including the inability to recall events while intoxicated, can occur.
Factors Influencing Alcohol’s Effects
The extent to which alcohol affects an individual can vary significantly due to several influencing factors. Body weight plays a role because a larger body mass generally means more fluid to dilute the alcohol, leading to a lower blood alcohol concentration (BAC). Gender differences also exist; women typically have a higher percentage of body fat and less body water than men, meaning the same amount of alcohol results in a higher BAC and greater effects.
The rate of consumption is an important factor; drinking alcohol quickly can overwhelm the body’s ability to process it, leading to a rapid increase in BAC. Food intake before or during drinking can slow down alcohol absorption from the stomach into the bloodstream. Individual tolerance, built up through regular consumption, can also influence perceived effects, though it does not change the actual BAC. Lastly, interactions with certain medications can amplify alcohol’s effects or interfere with its metabolism.
The Body’s Process of Eliminating Alcohol
The body primarily eliminates alcohol through a process called metabolism, which largely occurs in the liver. The liver contains specific enzymes responsible for breaking down alcohol into less harmful substances.
The first step involves the enzyme alcohol dehydrogenase (ADH), which converts alcohol into acetaldehyde, a toxic compound. Following this, another enzyme, aldehyde dehydrogenase (ALDH), quickly breaks down acetaldehyde into acetate, which is then further processed and eliminated from the body. The liver processes alcohol at a relatively constant rate, typically about one standard drink per hour. This fixed rate means that consuming alcohol faster than the liver can process it leads to its accumulation in the bloodstream, contributing to intoxication.