Absorption of Monomers

Introduction

• Discussion on how monomers are absorbed into the bloodstream.
• Focus on amino acids, monosaccharides, nucleosides, and fats.

Amino Acids Absorption

• Primary Active Transport
  • Uses ATP (Adenosine Triphosphate) as energy.
  • ATP is broken down to ADP (Adenosine Diphosphate) to release energy.
  • Energy utilized by proteins on enterocyte cell membrane.
  • Amino acids enter enterocytes (intestinal cells).
  • Transferred to blood capillaries, entering bloodstream for distribution.

Monosaccharides/Sugars Absorption

• Secondary Active Transport
  • Initially involves an ion gradient.
  • No direct use of ATP; uses energy from ion gradients.
  • Sodium ions flow down gradient, releasing energy.
  • Energy harnessed to transport sugars into enterocytes.
  • Sugars exit enterocyte via the blood capillaries into the bloodstream.

Nucleosides and Bases Absorption

• Similar mechanism to amino acids.
• Use primary active transport.
• Ultimately reach the blood capillaries.

Fats Absorption

• Diffusion
  • Non-polar tails allow passage through enterocyte membranes.
  • Inside enterocytes, fatty acids become chylomicrons.
  • Chylomicrons are too large for blood capillaries.
  • Absorbed by lymphatic capillaries (lacteals).
  • Further digested and broken down.
  • Eventually reach veins, then arteries for body distribution.

Key Locations in Absorption Process

• Duodenum: Primary site for digestion in GI tract.
• Jejunum: Primary site for absorption in GI tract.

Conclusion

• Overview of how major macromolecules are absorbed into the body.
• Understanding of different transport mechanisms for each type of macromolecule.