Laboratory Digestion in the Stomach and Small Intestine

Question 1

Food types digested in stomach based on experiment results

Answer 1

Mainly proteins, as evident by extensive digestion of egg white and yolk samples

Question 2

Function of pepsin and rennin in digestion

Answer 2

Pepsin (activated form of pepsinogen) digests proteins into peptides, rennin (present in infants) digests milk protein caseinogen

Question 3

How substances like histamine, caffeine, and alcohol affect digestion

Answer 3

Histamine increases acid secretion (aiding protein breakdown but causing ulcers in excess), caffeine has a milder effect, alcohol irritates stomach lining, delays digestion, and causes ulcers with prolonged consumption

Question 4

How stomach protects itself from secretions and how gastric secretion is modulated

Answer 4

Thick mucus layer with bicarbonate neutralizes acid, hormones like gastrin and somatostatin regulate acid production

Question 5

Methods to detect free hydrochloric acid besides the experiment

Answer 5

Augmented histamine test, endoscopic gastrin test, congo red test, serum pepsinogens, calcium carbonate breath test

Question 6

Gastric function in normal person, person with duodenal ulcer, and duodenitis

Answer 6

Normal: strong muscle contractions churn food with gastric juice. Duodenal ulcer: damage to lining weakens protection, leading to pain/bleeding. Duodenitis: irritation indirectly disrupts stomach motility

Question 7

Components of pancreatin and their actions

Answer 7

Trypsin breaks down proteins, amylase breaks down carbohydrates, lipase breaks down fats for absorption

Question 8

Principle behind decolorization of phenolphthalein as digestion indicator

Answer 8

Phenolphthalein turns colorless as proteins are broken down to amino acids. It was used as an indicator in the experiment but faulty titration might explain lack of color change

Question 9

Reagents and conditions necessary for digestion of fats, carbohydrates, and proteins

Answer 9

Vegetable oil, starch solution, egg white, pancreatin, bile salts, basic environment (sodium carbonate), Orlistat (optional) for lipase inhibition

Question 10

Digestion products formed from breakdown of vegetable oil, starch, and egg whites

Answer 10

Fatty acids & glycerols from oil, glucose from starch, amino acids from proteins. Experiment results: only solution D showed fatty acid/glycerol production, no starch digestion (iodine test), no protein digestion (biuret test)

Question 11

Effect of Orlistat and other substances on fat digestion

Answer 11

Orlistat inhibits lipase, reducing fat absorption. Other options: chitosan, glucomannan, psyllium husk

Question 12

Function of rennin in the stomach (before pepsin)

Answer 12

Rennin in young animals coagulates milk protein, allowing more time for digestion. It’s replaced by pepsin later

Question 13

Test tube with protein digestion and without

Answer 13

Most protein digestion in C (acid and enzyme), least in A (highest pH), none in E (no enzyme)

Question 14

Clinical significance of measuring free and total acidity

Answer 14

High acidity: excess acid, hyperacidity, duodenal ulcer. Low acidity: hypochloridria/achlorhydria, anemia, impaired digestion, increased infection risk

Question 15

Macromolecules digested in the small intestine

Answer 15

Lipids, proteins, and carbohydrates after food is converted to chyme in the stomach

Question 16

Enzymes responsible for carbohydrate digestion in the intestine

Answer 16

Pancreatic amylase, lactase, sucrase, maltase. Only test tube F (neutralizing agent, calcium chloride, bile salts) should show theoretical carb digestion

Question 17

Enzymes responsible for protein digestion and their functions

Answer 17

Trypsin and chymotrypsin cleave peptide bonds in proteins to form smaller peptides. Activated in alkaline environment

Question 18

Test tube showing protein digestion (theoretically)

Answer 18

Only test tube I (sodium carbonate, calcium chloride, bile salts) should show protein digestion due to optimal conditions