The human digestive system

• What are the major nutrients required for a healthy diet?

  Carbohydrates, proteins, and lipids
• What is the primary function of the digestive system?

  To break down large molecules of food for absorption into the bloodstream
• What are the two main functions of the human digestive system?

  • Breaks down complex food substances
  • Provides a large surface area for maximum absorption of food
• What is the role of the mouth in digestion?

  Begins the digestion of carbohydrates
• What does the stomach begin to digest?

  Protein
• What small molecules can be absorbed in the stomach?

  Small molecules such as alcohol
• What is the function of the duodenum in the small intestine?

  Continues the digestion of carbohydrates and proteins; begins the digestion of lipids
• What is the role of the ileum in digestion?

  Completes the digestion of carbohydrates and proteins into single sugars and amino acids; absorbs these along with fatty acids and glycerol
• What is the function of the large intestine?

  Absorption of water and egestion of undigested food
• What are digestive enzymes?

  Proteins that catalyse or speed up chemical reactions
• How do digestive enzymes function in the gut?

  They break down complex food molecules into small, soluble molecules
• What is the significance of the small intestine wall's structure?

  It is folded and has projections called villi to increase surface area for absorption
• What are villi?

  Finger-like projections in the small intestine that provide a large surface area for absorption
• What is the plural of villus?

  Villi
• What are microvilli?

  Projections from the surface of an epithelial cell of the small intestine wall
• How do villi and microvilli contribute to digestion?

  • Villi increase surface area for absorption
  • Microvilli further increase surface area on epithelial cells
  • Together, they enhance nutrient absorption efficiency
• What happens to most of the digested food after absorption?

  It passes through the epithelial cells of the gut wall and is carried by blood to the liver
• How do digested lipids enter the body after digestion?

  They pass through the gut wall and enter the lacteals
• What is the overall process of digestion in the human body?

  1. Ingestion of food
  2. Mechanical and chemical breakdown in the mouth and stomach
  3. Digestion in the small intestine (duodenum and ileum)
  4. Absorption of nutrients through villi and microvilli
  5. Transport of nutrients to the liver
  6. Egestion of undigested food