Alcoholic beverages contain ethanol, which impacts the body in various ways, leading to the familiar sensation of being drunk. This effect arises from alcohol’s journey through the bloodstream and its influence on brain chemistry. Understanding these processes clarifies how alcohol alters perception, coordination, and mood, contributing to intoxication.
Alcohol’s Path Through the Body
Once consumed, alcohol does not require digestion like food. A small amount can be absorbed directly through the lining of the mouth and stomach. However, the majority of alcohol absorption occurs rapidly in the small intestine due to its large surface area. From there, it enters the bloodstream, quickly circulating throughout the entire body.
Within minutes, alcohol travels to all organs, including the brain. Its small molecular size allows it to easily cross the blood-brain barrier, a protective filter that typically prevents many substances from entering the brain. This swift distribution means alcohol can begin to exert its effects on the central nervous system, often within 15 to 45 minutes, depending on absorption speed.
How Alcohol Alters Brain Function
Alcohol acts as a central nervous system depressant, primarily by interfering with the brain’s chemical messengers, known as neurotransmitters. It enhances the effects of gamma-aminobutyric acid (GABA), the brain’s main inhibitory neurotransmitter. This enhancement leads to a slowing of brain activity, contributing to feelings of relaxation, reduced anxiety, and observable effects like slurred speech and slowed reactions.
At the same time, alcohol inhibits glutamate, which is the brain’s primary excitatory neurotransmitter. By suppressing glutamate’s activity, alcohol further slows brain function, impairing cognitive processes such as judgment, decision-making, and memory formation. This inhibition can contribute to memory lapses or “blackouts” that occur with higher levels of consumption. Alcohol also influences dopamine and serotonin, which can affect mood and contribute to feelings of pleasure or altered emotional states.
These changes in neurotransmitter activity impact specific brain regions. Effects on the cerebellum, which coordinates movement, result in impaired balance and coordination. The frontal lobe, responsible for planning and impulse control, experiences reduced function, leading to impaired judgment and decision-making. Higher doses can also affect the brainstem, which regulates vital functions like breathing and heart rate.
Why Effects Vary Among Individuals
The way alcohol affects a person can differ significantly due to several interacting factors. The body’s metabolic enzymes play a substantial role, particularly alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH), which break down alcohol in the liver. Genetic variations in these enzymes can alter how quickly alcohol is processed; for example, some individuals, particularly those of East Asian descent, have an ALDH2 variant that makes them less efficient at breaking down a toxic byproduct of alcohol, leading to a “flush” reaction and lower alcohol tolerance.
Body composition also influences alcohol’s effects. Alcohol distributes in body water, meaning individuals with more body water, such as those with higher muscle mass, will have alcohol diluted across a larger volume, resulting in a lower blood alcohol concentration (BAC) for the same amount consumed. Conversely, individuals with a higher percentage of body fat, which contains less water, may experience a higher BAC. Gender differences in body water content and enzyme levels also contribute to varying effects, with women often reaching higher BACs than men for the same amount of alcohol.
Tolerance, developed through regular alcohol consumption, means the body adapts and requires more alcohol to achieve the same effects. This adaptation can involve changes in liver enzyme activity and neurotransmitter receptors. The presence of food in the stomach slows the absorption of alcohol into the bloodstream, as it keeps alcohol in the stomach longer before it moves to the small intestine, leading to a more gradual increase in BAC.
The Body’s Process of Sobering Up
The liver is the primary organ responsible for metabolizing alcohol and removing it from the body. Enzymes like ADH and ALDH in the liver convert alcohol into acetaldehyde, a toxic compound, which is then further broken down into acetate and eventually into carbon dioxide and water. This metabolic process is the main way the body eliminates alcohol.
The liver processes alcohol at a relatively constant rate, typically about one standard drink per hour, or approximately 0.015 grams per 100 milliliters per hour of blood alcohol concentration. This rate cannot be significantly sped up by external factors like drinking coffee, taking a cold shower, or exercising; these actions may only make an intoxicated person feel more awake without reducing their BAC. A small percentage of alcohol, around 2 to 10 percent, is eliminated unchanged through urine, breath, and sweat.