Adaptations of the Small Intestine for Absorption of Digestion Products

Introduction

• The lecture focuses on describing how the small intestine is adapted for absorbing digestion products.

Overview of Digestion

• Large food molecules are broken down into smaller molecules by enzymes during digestion.
• Example: Starch is digested into simple sugars by the enzyme amylase.
• Products of digestion are absorbed into the bloodstream in the small intestine.

Adaptations of the Small Intestine

Length of the Small Intestine

• The human small intestine is approximately 5 meters long.
• A long small intestine provides a large surface area for absorption of digestive products.

Structure of the Small Intestine

• Villi
  • The interior is covered with millions of villi.
  • Villi significantly increase the surface area for absorption.
• Microvilli
  • Located on the surface of villi.
  • Further increase the surface area.

Blood Supply and Concentration Gradient

• Villi have a very good blood supply.
• Rapid removal of digestion products by the bloodstream maintains a high concentration gradient.

Membrane Thickness

• Villi have a thin membrane.
• This ensures a short diffusion path.

Absorption Methods

• Diffusion
  • Rapid diffusion of digestion products into the bloodstream due to the adaptations mentioned.
• Active Transport
  • Molecules not absorbed by diffusion are absorbed by active transport.
  • Previously covered in an earlier video.

Additional Resources

• The lecture mentions a vision workbook with questions on the adaptations of the small intestine.

Conclusion

• The small intestine's adaptations facilitate efficient absorption of digestion products.