Digestive System Lecture Notes

Introduction to Digestion

• Definition: Digestion is the process by which food is broken down into small molecules for absorption by the body.
• Nutrient Groups: There are seven nutrient groups:
  1. Carbohydrates
  2. Protein
  3. Fat
  4. Vitamins
  5. Minerals
  6. Water
  7. Roughage
• Importance of a balanced diet with all nutrient groups.

Role of Teeth and Enzymes

• Teeth: Initial physical breakdown of food.
• Enzymes: Key players in chemical digestion.
  • Act as biological catalysts that speed up chemical reactions.
  • Vital for faster chemical reactions in living organisms.

Digestive Enzymes

• Carbohydrates:
  • Broken down by amylase into simple sugars like glucose.
  • Amylase is produced in the salivary glands, pancreas, and small intestine.
• Proteins:
  • Broken down by protease into amino acids.
  • Produced in the stomach, pancreas, and small intestine.
• Fats:
  • Broken down by lipase into fatty acids and glycerol.
  • Produced in the pancreas and small intestine.

Digestion Process

• Enzymes are produced in:
  • Pancreas
  • Small Intestine
  • Additional glands like salivary glands for amylase and stomach for protease.

Absorption in the Small Intestine

• Structure of Small Intestine: Muscular tissue facilitates movement of food via peristalsis.
• Villi:
  • Finger-like structures inside the intestine.
  • Large surface area for absorption.
  • Thin cell layer and rich blood supply for quick absorption.

Complete Digestive Journey

• Mouth: Initial breakdown by amylase.
• Esophagus: Food travels down to the stomach.
• Stomach: Proteins are further broken down by protease.
• Small Intestine: Further breakdown and absorption with folds and villi.
• Large Intestine: Absorption of excess water, formation of feces.
• Rectum: Storage of feces before expulsion.

Conclusion

• The digestive system efficiently breaks down food into absorbable units with the help of enzymes and physical structures like teeth and villi.
• From ingestion to expulsion, each part plays a significant role in ensuring nutrients are available to the body.