A diagram shows ethanol molecules crossing the intestinal epithelium into capillaries. Which physiological route correctly follows these molecules next and explains why the liver is the first major metabolic site?

• A. Capillaries drain into the portal vein, directing absorbed ethanol-rich blood to the liver where hepatic enzymes metabolize ethanol before it reaches systemic circulation.
• B. Absorbed ethanol enters the enteric nervous system which chemically modifies ethanol locally, then slowly releases it into systemic veins, minimizing hepatic exposure.
• C. Capillaries feed into lymphatic vessels that transport ethanol to the thoracic duct, which then deposits ethanol-rich lymph into the systemic circulation bypassing first-pass hepatic metabolism.
• D. Intestinal capillary blood is routed directly to the renal circulation for initial filtration because the kidneys filter small molecules prior to hepatic processing.

Answer: (A)