Final answer:
The liver is involved in drug metabolism, breaking down substances such as ethanol and nicotine. It also converts toxic ammonia into non-toxic urea. In liver disease or damage, toxic substances can accumulate in the blood and impair brain function.
Step-by-step explanation:
The liver is responsible for the breakdown or modification of various substances, a process known as drug metabolism. It breaks down ethanol into carbon dioxide and water, making it the traditional treatment for methanol and ethylene glycol poisoning. The liver also metabolizes nicotine into various breakdown products and converts toxic ammonia into non-toxic urea. In cases of liver disease or damage, the liver may not function properly, leading to the accumulation of toxic substances in the blood and impairment of brain function.