Gastrointestinal Lecture 4 Part 2 Digestion and Absorption of dietary carbs Flashcards
What cleaves polysaccharides?
What cleaves the disaccharides?
The products of carbohydrate digestion
The products of carbohydrate digestion are monosaccharides that must cross the intestinal epithelium to be absorbed into the body
Absorption of glucose/galactose
- Absorption of glucose/galactose is facilitated by secondary active transport
- SLGT-1 transports one molecule of glucose/galactose into intestine epithelial cell for every two Na+ ions that go in
- leaves via diffusion through GLUT2
- Na/K ATPase pump to replace Na+
Absorption of fructose
Absorption of fructose occurs by facilitated diffusion
Absorption of monosaccharides after a low sugar meal
normal
Absorption of monosaccharides after a high sugar meal
gets overwhelmed/ saturated
Summary of carbohydrate digestion and absorption
examples of dietary fibre
> cellulose (plant cell walls)
> Lignin (plant cell walls; woody)
> chitin (cell walls of fungi [mushrooms] & insect/crustacean exoskeletons)
physioloigcal effects of fibre
- Delayed gastric emptying and increased satiety
-
Impaired absorption in the small intestine
> multiple mechanisms: trapping, interfering, inhibiting
> Protective:
- delayed absorption of carbohydrates (better glucose control)
- Impaired cholesterol absorption
- Trapping of trace elements and possible toxic compounds
3. Fiber fermentation in the large intestine
> gut microbiota can ferment undigested fiber to produce short-chain fatty acids
4. Fecal bulking
> undigested fiber (mass and retained water), and increased bacterial mass secondary to fiber fermentation