Digestive System Enzymes and the Role of Bile

Introduction

• Focus on enzymes involved in digestion.
• Enzymes catalyze, or speed up, chemical reactions.
• Enzymes are large protein molecules with an active site where the substrate attaches.
• The substrate is the molecule that the enzyme breaks down.

Key Concepts

• Active Site: A groove on the enzyme's surface where the substrate fits.
• Specificity: Enzymes are specific; a substrate must fit perfectly into the active site (Lock and Key Theory).

Enzymes in the Digestive System

Protease

• Function: Breaks down proteins into amino acids.
• Location: Found in the stomach, pancreatic fluid, and the small intestine.
• Process: Converts protein into individual amino acids, which are absorbed into the bloodstream and reassembled into human proteins by body cells.

Carbohydrase

• Example: Amylase.
• Function: Breaks down carbohydrates like starch into simple sugars.
• Location: Found in saliva and pancreatic fluid.
• Process: Digests starch, which consists of glucose molecule chains.

Lipase

• Function: Breaks down lipids into glycerol and fatty acids.
• Location: Found in pancreatic fluid and the small intestine.
• Structure: Lipids are composed of glycerol attached to three fatty acids.

Role of Bile

• Production: Made in the liver, stored in the gallbladder.
• Function: Speeds up lipid digestion, but is not an enzyme.
• Emulsification: Converts large lipid droplets into smaller ones, increasing surface area for lipase activity.
• Alkalinity: Neutralizes stomach acids, creating alkaline conditions in the small intestine, enhancing lipid digestion by lipase.

Conclusion

• The lecture outlined the functions of key digestive enzymes and the role of bile in lipid digestion.
• Emphasized the importance of enzyme specificity and the lock and key theory.
• Mentioned the availability of a revision workbook for more practice on this topic.