4.0 Introduction

The term absorption can have a number of different meanings. Not everything that is taken up into the enterocyte from the lumen of the GI tract will be absorbed, so the term uptake refers to compounds being transported into the enterocyte. Absorption means that a compound is transported from the enterocyte into the bloodstream for circulation throughout the body.

Under most circumstances, compounds that are taken up into the enterocytes will then be absorbed into the bloodstream. After this chapter, hopefully this distinction between these terms will be clear. After later micronutrient chapters, hopefully you will understand the reason for emphasizing this distinction.

Sections:

• 4.1 Crypts of Lieberkuhn & Enterocyte Maturation
• 4.2 Absorptive Lineup & Cell Membranes
• 4.3 Transport Mechanisms Used for Uptake and Absorption
• 4.4 Carbohydrate Uptake, Absorption, Transport & Liver Uptake
• 4.5 Protein Uptake, Absorption, Transport & Liver Uptake
• 4.6 Lipid Uptake, Absorption & Transport
• 4.7 Glycemic Response, Insulin & Glucagon