Hubi 2003 (MUN) - Chapter 2: Digestion (Carbohydrate Digestion)

What are the possible end products of carbohydrate digestion?

Simple Carbohydrates and Complex Carbohydrates.

What are the two types of simple carbohydrates that could be end products of carbohydrate digestion?

Monosaccharides and Disaccharides.

What are the different types of monosaccharides?

- Glucose

- Fructose

- Galactose

What are the different types of disaccharides?

- Sucrose

- Lactose

- Maltose

What are the two types of complex carbohydrates that could be end products of carbohydrate digestion?

Oligosaccharides and Polysaccharides.

What are the different types of oligosaccharides?

- Raffinose

- Stachyose

What are the different types of polysaccharides?

- Starch

- Glycogen

What are the most common end products of carbohydrate digestion?

Monosaccharides (glucose, fructose, and galactose).

Step 1 of Carbohydrate Digestion

Salivary alpha-amylase initiates the digestion of carbohydrates. Carbohydrates then get digested through pancreatic alpha-amylase in the small intestine.

alpha-Amylase

A pancreatic and salivary enzyme that digests starch and glycogen by cleaving the alpha-1,4 linkages of starch and glycogen.

What are the products of starch?

- Maltose

- Maltotriase

- alpha-Limit dextrin

Maltose and Maltotriose both contain alpha-1,4 linkages. What type of linkage is in alpha-Limit dextrin?

alpha-1,6 linkages, which are not broken down by alpha-Amylase.

Step 2 of Carbohydrate Digestion

Two of the end products, glucose and galactose, are transported into the intestinal epithelial cells by a secondary active transport process that is carried out by the sodium-glucose linked transporter (SGLT).

Step 3 of Carbohydrate Digestion

The last end product, fructose, diffuses across the cell membrane through a transporter called glucose transporter 5 (GLUT5).

Step 4 of Carbohydrate Digestion

Glucose Transporter 2 (GLUT2) releases all three end products into the bloodstream, where they can travel to other tissues to be used as fuel.