Digestive System: Enzymes and More

• The digestive system is a complex system responsible for breaking down food, absorbing nutrients, and eliminating waste

Digestive System Fundamentals

• Microvilli increase the surface area of the small intestine for nutrient absorption
• The liver is responsible for detoxification and bile production
• Bile emulsifies lipids to increase surface area for enzyme activity
• Fatty acids are absorbed into the lacteals instead of the blood capillaries in the villi
• Acidic chyme in the small intestine stimulates the release of secretin

Enzyme Activity & pH Regulation

• Pepsin shows the highest activity in a test tube with a pH of 2.0
• If trypsin was exposed to the highly acidic environment of the stomach, it is likely to be denatured and lose function
• An unknown enzyme from the digestive system that functions best at a pH of 7.0 and breaks down carbohydrates is most likely amylase
• A sharp decrease in enzyme activity at 80°C is most likely because the enzyme was denatured and lost its function
• To determine the effect of bile salts on lipid digestion, measuring lipid breakdown in the presence and absence of bile salts would be most effective

Nutrient Absorption & Transport

• Fats are absorbed into lacteals instead of directly into the bloodstream because they are too large to pass through capillaries
• Glucose is absorbed via secondary active transport with sodium ions in the small intestine
• A patient that has a mutation that prevents the production of intrinsic factor is likely to develop Vitamin B12 deficiency
• After injecting a dye into the hepatic portal vein, the liver will be reached first
• If glucose is unable to be absorbed in the small intestine, the sodium-glucose cotransporter (SGLT-1) is most likely malfunctioning

Digestive Disorders & Experimental Analysis

• Celiac disease is characterized by an autoimmune reaction to gluten, leading to villi damage
• GERD results from excessive acid reflux, potentially leading to esophageal damage
• A patient with severe dehydration is found to have decreased function in the large intestine. This is most likely because of insufficient water absorption
• In a clinical trial investigating the effectiveness of a new drug designed to treat lactose intolerance, the amount of lactose consumed should be controlled
• A study analyzes nutrient absorption rates in patients with and without Crohn’s disease. The results show decreased amino acid and fatty acid absorption in Crohn’s patients because the disease damages the small intestine’s absorptive surface