Understanding Polysaccharides and Gut Flora

What type of linkages are found in cellulose?

Which polysaccharide is primarily made of fructose and is good for digestion?

Which organism relies on symbiotic gut microflora to digest cellulose?

Which transporter is responsible for transporting fructose into the cell?

How do termites reconstitute their gut flora?

Which is crucial for the absorption of carbohydrates at the brush border?

What change occurs to the villi in the gut of animals during high digestion periods?

Where does the majority of the biotransformation of phenylephrine occur?

What happens to the absorption of monomers after digestion in the small intestine?

Which of the following is NOT a carbohydrate transporter at the brush border?

Other Polysaccharides

Cellulose is a poly-glucose molecule with β-1,4 linkages.
Inulin is a poly-fructose molecule found in some plants instead of starch. It aids digestion, promotes satiety, and is difficult for the body to break down.
Vertebrates lack enzymes to break down cellulose and inulin.
They rely on symbiotic gut microflora, a process that occurs in the large intestine, not the small intestine.
This results in gas production.

Symbiotic Gut Flora

Symbiotic protists aid termites in digesting cellulose and lignin.
Termites must shed their exoskeletons (moult) to grow.
The lining of the digestive tract is also molted during this process.
To replenish the gut flora, termites consume the feces of nestmates.

Absorption of Carbohydrates at the Brush Border

The Na+/K+ pump maintains a sodium gradient, driving sodium from the lumen into absorptive cells.
SGLT1 co-transports sodium and glucose into the cell.
Fructose enters the cell via the GLUT5 transporter, moving down its concentration gradient.
Glucose, galactose, and fructose are transported into interstitial fluid by facilitated diffusion, moving down their concentration gradient.
Other sugars follow a similar transport pathway.
Gut surface area can be increased by extending villi, especially during periods of high digestion, such as summer, then reduced during winter or hibernation.

Post-Absorption Processing

Phenylephrine is rapidly metabolized (typically by conjugation to a sulfate group) primarily in the intestinal epithelium.
This leaves little active phenylephrine in circulation, limiting its systemic effects.
The small intestine is a crucial site for absorption.

This quiz covers the structure and function of various polysaccharides, including cellulose and inulin, as well as their role in digestion and symbiotic relationships with gut flora. It also discusses the absorption mechanisms of carbohydrates at the brush border in the digestive system.