Physiological Effects: Alcohol


Blood Alcohol Content Effect

Above you will find a picture that shows which areas of the brain are affected as the BAC level continues to increase. As the BAC increases, more and more of certain areas of the brain are effected.



Within alcoholic beverages we find ethanol, aka ethyl alcohol, however it is not pure ethanol as that would be dangerous and deadly. Instead, there are specific amounts of concentrations of ethanol by volume in the beverages. Each different kind of beverage has a different amount of ethanol concentration in it, depending on what type of beverage it is. There are beers, wines, and champagnes that have a much lower ethanol concentration (typically between 4.5-12%) than distilled spirits such as vodka, rum, gin, and whiskey which typically contain ethanol concentrations between 40-95%. However, the most typical spirits that you find at the liquor store are around 40%.



Alcohol effects men and women differently, even if they are the same height/weight. This is due to the fact that men tend to have more muscle and less fat than women do. When alcohol enters the body, it gets absorbed through the muscle tissue, but muscle tissue water in it therefore making the alcohol more diluted depending on how much muscle tissue you have. Because men typically have more muscle tissue, this is why they will have a lower BAC than women if they drink the same amount of alcohol and won’t feel the effects of the alcohol as quickly as the women will. “…about 20 percent of the alcohol is absorbed in the stomach and about 80 percent is absorbed in the small intestine” (“How Alcohol Works”).

How fast the alcohol is absorbed depends on the ethanol concentration in the drink, like discussed above, which means the more the ethanol in the drink, the faster it is absorbed. It also depends on what you are mixing the alcohol with. Carbonated beverages speed up the absorption of alcohol, so soda will make it absorb faster than juice or Gatorade would. Lastly, it depends on the amount of food in your stomach. If your stomach is empty, the alcohol will absorb faster, but if it’s full then the alcohol will absorb slower. After the alcohol is absorbed, it then enters the bloodstream and is dissolved in the water in the blood. Now that the alcohol is dissolved into the blood, the blood carries that alcohol into the tissues of the body and dissolves in the water within the tissues.

Because the alcohol is in your bloodstream, which obviously runs to your brain, this is how it reaches and effects the brain. At this step, the effects of the alcohol are finally exerted onto the body. The amount of effects felt/the intensity of them depend on how high the person’s BAC (blood alcohol concentration) is which depends on the amount of alcohol consumed. The more alcohol consumed, the higher the BAC. “The BAC can rise significantly within 20 minutes after having a drink”.



After the alcohol is absorbed in the bloodstream, it begins the process of leaving the body. This is done through three different organs: the kidney, the lungs, and the liver. The kidney eliminates 5% of the alcohol in the urine. We exhale out 5% of the alcohol using our lungs, which is how breathalyzer devices are able to detect what our BAC is. And finally, “the liver chemically breaks down the remaining alcohol into acetic acid”, using a process called oxidation. The body literally sees alcohol as poison and attacks the substance by producing an enzyme called ‘alcohol dehydrogenase’. The enzyme attacks the alcohol when it makes an attempt to pass your stomach lining, and then when it reaches the liver. These actually help decrease the prevalence of a hangover, depending on how much you drink and how much of a fight the enzymes have to put up.

The average person can eliminate 0.5oz (15ml) of alcohol per hour, which means it takes an hour to eliminate the alcohol from a 12oz (355ml) can of beer. Typically, people are drinking much more than a can of beer per hour, which means our bodies are absorbing alcohol faster than it is eliminating alcohol. This is how our BAC levels increase quickly.



When the alcohol reaches the brain, it targets the nerve cells. Because of this, it interferes with the communication between the nerve cells and the rest of the cells, “suppressing the activities of excitatory nerve pathways and increasing the activities of inhibitory nerve pathways” (“How Alcohol Works”). Alcohol specifically enhances the effects of the neurotransmitter GABA, as it is an inhibitory transmitter. Since it mainly effects our inhibitory transmitters/nerves, this is why people who consume alcohol experience many behavioral effects/a lack of ability to keep their impulses under control. The order in which alcohol affects the various brain centers is as follows: cerebral cortex, limbic system, cerebellum, hypothalamus and pituitary gland, medulla (brain stem).

The cerebral cortex is the highest portion of your brain that is responsible for processing information from your senses, controlling your thought processes/consciousness, initiates most voluntary muscle movements, and influences lower-order brain centers. In the cerebral cortex, alcohol depresses the behavioral inhibitory centers which makes the person more talkative, more self-confident, and less socially inhibited. It also slows down information processing from the senses which is what causes blurred vision, and also trouble hearing, smelling, tasting, and touching. The threshold for pain is also raised, meaning it is harder to reach the point of feeling pain. Lastly it inhibits thought processing which makes the person incapable of thinking clearly or making good judgments.

The limbic system is the center of the brain containing two areas called the hippocampus and the septal area, and is responsible for controlling emotions and memory. In the limbic system, alcohol exaggerates the person’s emotions which causes anger, verbal/physical aggression, withdrawal, and tearfulness/sadness. It also causes memory loss which is why there can be lapses of memory throughout the night, or a total blackout.

The cerebellum coordinates the movement of muscles/controls fine movements and balance. In the cerebellum, alcohol effects fine muscle movements, and makes them uncoordinated, shaky, and jerky. Movements people would normally be able to make smoothly with a fully functioning cerebellum, become clumsy and graceless. It also causes the person to lose their balance frequently, and makes it more difficult for them to walk/hold themselves up.

The hypothalamus and pituitary gland. The hypothalamus controls and influences automatic functions on the brain through actions on the medulla. Also “coordinates many chemical or endocrine functions (secretions of sex, thyroid and growth hormones) through chemical and nerve impulse actions on the pituitary gland.” In the hypothalamus and pituitary gland, alcohol influences sexual behavior by depressing the nerve centers in the hypothalamus that controls sexual arousal and performance. So, this causes sexual behavior to increase, but sexual performance to decline. It also inhibits the pituitary secretion of anti-diuretic hormone (ADH), which acts on the kidney to reabsorb water in order to create less urine and not have to pee as often. The alcohol reduces the circulation levels of ADH causing the levels to drop, which then causes the kidney to produce more urine.

The medulla (brain stem) controls/influences all of the bodily functions that you don’t need to think about, AKA involuntary functions, such as breathing, heart rate, temperature, and consciousness. When the alcohol begins to effect this part of the brain it is extremely dangerous and can be fatal. In the medulla, alcohol influences the reticular formation, causing the person to feel sleepy. As the BAC increases, they can become unconscious. In addition, it influences breathing, heart rate, and temperature centers IF the BAC gets high enough. If this happens, the person will breathe slowly or stop breathing altogether. Also, their blood pressure and body temperature will fall.




Written and Research Conducted by: Alexx Gillespie