Final answer:
The primary pathway for metabolism of small amounts of alcohol is the alcohol dehydrogenase pathway, which converts ethanol to acetaldehyde using alcohol dehydrogenase and is responsible for the majority of ethanol processing in the liver.
Step-by-step explanation:
The primary pathway used in the metabolism of small amounts of alcohol is the alcohol dehydrogenase pathway. This pathway is responsible for about 80 to 90% of the total hepatic ethanol uptake. In this pathway, the enzyme alcohol dehydrogenase catalyzes the oxidation of ethanol to acetaldehyde, producing NADH and H+ ion as byproducts. Acetaldehyde is highly toxic and is further metabolized by acetaldehyde dehydrogenase (ALDH) to a non-toxic molecule, acetate. This pathway is the most active when small amounts of alcohol are consumed, as compared to the microsomal ethanol oxidizing system (MEOS), which becomes more involved during heavy drinking.