The document discusses the enzymatic digestion and absorption of nutrients in the small intestine. It describes how disaccharides and small peptides are broken down by disaccharidases and aminopeptidases, respectively, on the brush border of intestinal cells and the resulting monosaccharides and amino acids are absorbed. It also explains how fatty acids and monoglycerides from triglyceride digestion are incorporated into micelles and absorbed by intestinal cells, where they are reassembled into triglycerides and secreted into the lymphatic system within lipoprotein particles called chylomicrons.

1. BC1502 Introduction to Cell and Molecular Biology
Macromolecules
Nutrition & biochemistry
Lecture 5b
James A Martiney, Ph.D.

2. Enzymatic Digestion of Nutrients
Figure 47-9 p1053

3. Absorption and digestion of
disaccharides and small peptides
Lumen
of small
intestine
Brushborder
cells of
intestinal
mucosa
Polysaccharides
Small peptides
and disaccharides
Disaccharidases Aminopeptidases
Monosaccharides Amino acids
To extracellular fluid and blood
Figure 47-14 p1057

4. Absorption of fat-soluble products of digestion
by intestinal mucosa cells
Monoglycerides Fatty acids
Lumen
of small
intestine
Bile salts
Micelles
Brushborder
cells of
intestinal
mucosa
Endoplasmic
reticulum
Monoglycerides
Triglycerides
Aggregated
Aggregate and coated
triglycerides
Lipoprotein with lipoprotein
coat
Chylomicron
Interstitial
fluid
Fatty acids
Chylomicrons
Chylomicrons exit the cell by
exocytosis and enter lymph vessels.
Figure 47-15 p1058