Absorption of Carbohydrates, Protein and Fat

This is pretty much a recap of PHYL2001, but oh well.

Actually, you know what? This IS a recap of PHYL2001. More specifically, it's a recap of Gastrointestinal Function part 3. So re-read that post, and you should be set.

FUN FACTS NOT IN THE ABOVE POST:

• The middle of the intestinal lumen is the "stirred layer," and it's where mixing occurs. The area closer to the cells is the "unstirred layer." In the unstirred layer, food is trapped by the glycocalyx on the brush border.
• Carbohydrates must be broken down completely for absorption, as only monosaccharides can be absorbed.
• SGLT1 (the transporter that absorbs galactose and glucose) requires secondary active transport with Na+. Na+ concentrations are kept low via the Na+/K+ pump.
• Glucoamylase, one of the brush border enzymes that breaks down carbohydrates, is also known as maltase.
• Unlike carbohydrates, very short chains of amino acids (di- and tripeptides) can be absorbed. They are absorbed via the PepT1 transporter, which uses secondary active transport with H+.
• The H+ gradient for PepT1 is maintained via a Na+/H+ antiport.
• Amino acids are all taken up by specific transporters. I'm pretty sure these also undergo secondary active transport with Na+, but the slide says Na+ independent, so I'm really confused now...