Final answer:
The liver metabolizes alcohol at a rate limited by its own capacity, with significant contributions from the alcohol dehydrogenase system and the MEOS system. It takes roughly 2.5 hours to metabolize the ethanol in a standard drink, but for legally intoxicated individuals, a minimum of five hours is needed for sobriety.
Step-by-step explanation:
The liver primarily metabolizes alcohol, processing it through two main systems: the alcohol dehydrogenase system and the microsomal ethanol oxidizing system (MEOS). About 80 to 90% of ethanol is processed by the former, where alcohol dehydrogenase converts ethanol into acetaldehyde, a toxic substance that is subsequently converted into acetate by acetaldehyde dehydrogenase. This is how the liver protects itself from the toxic effects of acetaldehyde. For the average person, it takes approximately 2.5 hours to metabolize 15 mL of ethanol, which is roughly the amount found in a standard drink (12 oz beer, 5 oz wine, or a shot of distilled spirits).
Allowing the liver enough time to fully metabolize ingested alcohol is crucial to avoiding alcohol toxicity. Actions such as drinking coffee or taking a shower do not expedite this process. For a legally intoxicated person, achieving sobriety from a BAC of 0.08 could take at least five hours post-drinking, considering the liver's metabolic and excretion rates.