Digestive System Questions part b

What are brush border enzymes?

Brush border enzymes are enzymes associated with the microvilli of the enterocytes of the small intestine mucosal cells.

What stimulates CCK release and what are its effects on the digestive process?

CCK is released in response to the entry into the duodenum of chyme rich in protein in fat. This causes pancreatic acini cells to release digestive enzymes.

Distension of the stomach and duodenal walls have different effects of stomach secretory activity. What are these effects?

Distension of the stomach enhances stomach secretory activity. Distension of the SI reduces stomach secretory activity. This gives the SI time to to carry out digestive and absorptive activities.

What common advantage do circular folds, villi, and microvilli provide to the digestive process?

Increase the surface area of the SI

What is the MMC and why is it important?

Migrating mobility complex; a pattern of peristalsis seen in the small intestine that moves the last remnants of a meal plus bacteria and other debris into the large intestine. MMC is important to prevent the over growth of bacteria in the small intestine.

What is the makeup of the fluid in the pancreatic duct? In the cystic duct? In the bile duct?

Pancreatic duct - bicarbonate-rich and enzyme rich. Cystic duct and bile duct is bile

What is the functional difference between pancreatic acini and islets?

Acini produce the exocrine products of the pancreas such as digestive enzymes and bicarbonate juice. The islets produce pancreatic hormones such as insulin.

Two substances secreted by cells of the gastric glands are needed to produce the active protein-digesting enzyme pepsin. What are these substances and which cells secrete them?

Parietal cells produce HCl which is needed to activate the inactive enzyme pepsinogen, which is secreted by chief cells.

How does the presence of food in the small intestine inhibit gastric secretion and motility?

The presence of food in the duodenum inhibits gastric activity by triggering the enterogastric reflex and the secretion of entergastrones.

Name the three phases of gastric secretion.

1. cephalic phase 2. gastric phase 3. intestinal phase

Describe the process by which solids are broken apart into smaller pieces in the stomach

Peristaltic action becomes more and more powerful as they approach the pylorous. Only a bit of chyme can pass through the pyloric sphincter at a time. When the pyloric sphincter is closed it is left in the sphincter.

What is the importance of enterohepatic circulation?

Recycling of bile salts that are needed for fat absorption.

After a meal, what is the small intestine's most common motility pattern? Why?

Segmentation is the most common motility pattern after a meal. Segmentation mixes chyme with digestive enzymes and exposes the products of this digestion to the absorptive epithelium where brush border enzymes finish digestion.