Biochemistry Chapter on Carbohydrates

Salivary alpha-amylase and Dextrin

• Salivary alpha-amylase breaks down starch by hydrolyzing alpha 1-4 glycosidic bonds.
• Dextrin is a product of this enzymatic action.
• Amylopectin is a branched polymer, contributing to the complexity of starch digestion.

Carbohydrate Absorption in the Small Intestine

• Most carbohydrates are absorbed in the lower jejunum and ileum.

Monosaccharide Classification

• The carbonyl group determines whether a monosaccharide is an aldose or a ketose.

Glycogen Structure

• The major bonds in glycogen are alpha 1-4 glycosidic bonds.

Disaccharidase Deficiency

• Deficiency in specific disaccharidase activities leads to undigested carbohydrates reaching the large intestine.
• This results in enhanced bacterial fermentation in the small intestine and osmotic diarrhea.

Glucose as a Cellular Fuel

• Glucose is a primary cellular fuel and the precursor for glycogen synthesis.

Carbohydrate Absorption Mechanisms

• Glucose and galactose are transported via the sodium-dependent glucose cotransporter 1 (SGLT-1) into the mucosal cells.
• Glucose transport is insulin-independent in jejunal mucosal cells.
• Fructose is absorbed through the GLUT-5 transporter.

Salivary Amylase Action

• Salivary amylase breaks down starch.

Maltose Breakdown

• One molecule of maltose produces two glucose molecules upon hydrolysis.

Final Carbohydrate Digestion

• Final carbohydrate digestion occurs in the upper jejunum.

Undigested Carbohydrates in the Large Intestine

• Undigested carbohydrates reaching the large intestine cause osmotic diarrhea.

Glucose and Galactose Absorption

• Glucose and galactose are transported across the intestinal mucosal cell membrane using the GLUT-2 transporter.

Carbohydrate Function

• Carbohydrates provide energy.
• They do not function as anticoagulants or form cell membranes.

Lactase Production

• Lactase is produced in the intestine.

Carbohydrate General Formula

• The general empirical formula of carbohydrates is (CH2O)n.

Glucose Uptake

• Glucose uptake from intestinal cells is insulin-independent.

Lactose Intolerance

• Lactose intolerance is caused by a deficiency in lactase.
• Treatment involves avoiding dairy products or taking lactase supplements.

Initial Carbohydrate Breakdown

• The initial breakdown of carbohydrates begins in the mouth.

Pancreatic Amylase Action

• Pancreatic amylase acts on carbohydrates in the small intestine.

Indigestible Carbohydrates

• Cellulose cannot be digested by humans.

Stomach Acidity and Carbohydrate Digestion

• Acidic stomach content reaching the small intestine inactivates pancreatic alpha-amylase, temporarily halting carbohydrate digestion.
• This is neutralized by bicarbonate.

Explore the intricacies of carbohydrate digestion and absorption in this quiz. Topics include salivary alpha-amylase, glucose metabolism, and disaccharidase deficiencies. Test your understanding of carbohydrate structures and their roles in human physiology.