Question

12. The pancreatic hormone regulates the absorptive state, while regulates the postabsorptive state 13. The single digestive function of the liver is to produce 14. List the four organic components of bile. w 15. Intestinal digestive enzymes that are embedded in the epithelial microvilli membranes are called enzymes 16. Acid in the intestine causes the release of 17. The intestinal hormone causes contraction of the gallbladder and release of bile into the duodenim 18. protects the wall of the large intestine from mechanical damage and from damage by bacterial acid.

Answer 1

12. Insulin is the hormone released in the absorptive state. Ingestion of food causes digestion of food in stomach and small intestine. Increased glucose absorption causes increase glucose levels in blood. Increased sugar levels causes release of insulin by beta cells of Islets of Langerhans in pancreas. Insulin causes increase entry of glucose into cells for glycolysis. It also increases storage of glucose as glycogen. Post-absorptive state is after all glucose is utilized. In this state, glucose levels declines which leads to release of glucagon by alpha cells of Islets of Langerhans in pancreas. Glucagon causes release of glucose by gluconeogenesis and glycogenolysis.

Right choice: insulin; glucagon.

13. Bile is released by the liver which is then transported by bile ducts into small intestine. It helps in digestion of fats by the small intestine as it causes emulsification of triglycerides. Thus, bile secreted by liver aids in digestion.

Right choice: Bile.

14. Bile is primarily composed of bile salts, cholesterol, phospholipids, bilirubin and inorganic salts along with water. The organic components include bile salts, phospholipids such as lecithin, pigments such as bilirubin and cholesterol. Bile salts are water soluble products released by metabolism of cholesterol, a sterol. These include cholic acid, and chenodeoxycholic acid (CDCA). Bilirubin is yellow pigment produced by breakdown of red blood cells. Lecithin is involved in fat absorption from the intestinal lumen by epithelial cells.

Right choice:

1. Bile salts

2. Cholesterol

3. Phospholipid like lecithin

4. Pigments like bilirubin.

15. Brush border enzymes are the digestive enzymes that are embedded in the microvilli of apical epithelial cell membrane of small intestine. These enzymes include sucrose, maltase, dextrinase, glucoamylase and sometime lactase. They are involved in digestion of most carbohydrates in food. They are located in the membrane close to the transporter proteins and are produced by enterocytes.

Right choice: Brush border enzymes.

16. Hydrochloric acid is released into stomach and aids in the digestion of food. When this stomach acid, enters the small intestine with chyme, it causes the pH of duodenum of small intestine to reduce. This reduced pH stimulates the release of hormone secretin. Secretin will reduce the pH of intestine by inhibiting stomach acid production by stomach parietal cells. It also stimulates the pancreatic ductal cells to release bicarbonate.

Right choice: secretin.

17. Cholecystokinin or CCK is the enzyme released by intestine when food enters the digestive tract. It stimulates the contraction of gall bladder. This contraction is via Sphincter of Oddi. It will regulate bile release from gall bladder to duodenum for fat digestion. It also stimulates the pancreas to release pancreatic exocrine enzymes for digestion.

Right choice: cholecystokinin.

18. Large intestine secretes alkaline mucus. This mucus has higher pH which will protect the large intestine from the acid. Acid is produced in large intestine by the metabolism of normal flora organism that aid in digestion of food. Lactic acid is produced by lactic acid bacteria during bacterial metabolism that may cause damage to intestinal epithelial cells. Alkaline mucus will neutralize this acid produced. It also prevents mechanical damage to the epithelium of large intestine.

Right choice: Alkaline mucus.