Lecture Notes: Alcohol Dehydrogenase and Small Intestine

Alcohol Dehydrogenase

• Function: Breaks down alcohol, specifically ethyl alcohol (the type consumed in drinks).
• Location: Found in the stomach and liver.
• Importance of Food:
  • Eating food, especially high in protein and fat (e.g., pizza, cheeseburger), slows alcohol absorption by keeping it in the stomach longer.
  • Consuming alcohol on an empty stomach leads to faster absorption and more immediate effects.
• Variation Among Individuals:
  • Men generally have more alcohol dehydrogenase compared to women.
  • Younger individuals tend to have more than older individuals.
  • Genetic differences affect levels of alcohol dehydrogenase.

Other Alcohol Breakdown

• Methyl Alcohol (Methanol):
  • Converted to formaldehyde upon breakdown by alcohol dehydrogenase.
  • Historical context: Prohibition era bathtub gin resulted in blindness and death due to formaldehyde.
• Ethylene Glycol (Antifreeze):
  • Broken down into a toxic product that affects the kidneys and tissues.
  • In cases of poisoning, ethyl alcohol can be administered because alcohol dehydrogenase prefers it, reducing breakdown of ethylene glycol.

Small Intestine

• Parts: Duodenum, Jejunum, Ileum
• Structure:
  • Villi: Finger-like projections for absorption and digestion.
  • Crypts: Indentations between villi.

Duodenum

• Features:
  • Contains Brunner's glands which secrete alkaline mucus.
  • Alkaline mucus neutralizes chyme acidity from the stomach.
  • Known as the "mixing bowl" due to mixing of bile, pancreatic juice, and chyme.
• Connections:
  • Connects to the stomach, liver, and pancreas.
  • Receives pancreatic juice (enzymatic secretions) and bile via ducts.
  • Pancreatic juice and bile are alkaline, aiding in neutralizing the chyme.
• Process:
  • Chyme enters duodenum in small amounts (tablespoon at a time).
  • Alkaline secretions optimize pH for enzymes in the small intestine.

Mucosal Layer

• Villi: Site of absorption and digestion.
• Crypts: Areas between villi.
• Importance: Alkaline environment in duodenum essential for enzyme activity.
  • Enzymes require alkaline pH for optimal function.

These notes provide a comprehensive overview of the roles of alcohol dehydrogenase in alcohol metabolism and the functional anatomy of the small intestine, particularly the duodenum's role in digestion.