BPK 105 Study Guide - Final Guide: Simple Columnar Epithelium, Gastrointestinal Tract, Gastric Pits
27 Apr 2018
School
Department
Course
Professor
Module 11 - Review Questions - Part 3
5. Describe the intestinal phase of stomach secretion. Describe the hormones and
pathways involved in modifying gastric activity. [5 marks]
- The intestinal phase of gastric secretion primarily inhibits gastric secretions (figure
16.11c
).
- controlled by the entrance of acidic chyme into the duodenum, which initiates both
neural and hormonal mechanisms.
- When the pH of the chyme entering the intestinal phase the duodenum drops to 2.0 or
below, the inhibitory influence of the intestinal phase is greatest.
- The hormone secretin, which inhibits gastric secretions, is released from the duodenum
in response to low pH (table 16.2). Fatty acids and peptides in the duodenum initiate the
release of the hormone cholecystokinin, which also inhibits gastric secretions (table
16.2).
- Acidic chyme (pH < 2.0) in the duodenum also inhibits CNS stimulation and initiates local
reflexes that inhibit gastric secretion.
6. Compare and contrast the structure of the mucosal layers of the stomach and small
intestine. What does this tell you about the roles of the stomach and small intestine
within the digestive system? Provide a brief description of two specialized structures
from each organ’s mucosal layer to support your discussion of its role. [8 marks]
STOMACH:
The submucosa and mucosa of the stomach are thrown into large folds called rugae (figure 16.10a
) when
the stomach is empty. These folds allow the mucosa and submucosa to stretch, and the folds disappear
as the stomach is filled.
The stomach is lined with simple columnar epithelium. The mucosal surface forms numerous tubelike
gastric pits (figure 16.10b
), which are the openings for the gastric glands. The epithelial cells of the
stomach can be divided into five groups. The first group consists of surface mucous cells on the inner
surface of the stomach and lining the gastric pits. Those cells produce mucus, which coats and protects
the stomach lining. The remaining four cell types are in the gastric glands. They are
1. mucous neck cells, which produce mucus;
2. parietal cells, which produce hydrochloric acid and intrinsic factor;
3. endocrine cells, which produce regulatory chemicals; and
4. chief cells, which produce pepsinogen, a precursor of the protein-digesting enzyme pepsin.
SMALL INTESTINE:
The small intestine is the major site of digestion and absorption of food, which are accomplished
due to the presence of a large surface area.
- The small intestine has three modifications that increase its surface area about 600-fold:
circular folds, villi, and microvilli.
Document Summary
Module 11 - review questions - part 3: describe the intestinal phase of stomach secretion. Describe the hormones and pathways involved in modifying gastric activity. The intestinal phase of gastric secretion primarily inhibits gastric secretions (figure. 16. 11 c ). controlled by the entrance of acidic chyme into the duodenum, which initiates both neural and hormonal mechanisms. When the ph of the chyme entering the intestinal phase the duodenum drops to 2. 0 or below, the inhibitory influence of the intestinal phase is greatest. The hormone secretin, which inhibits gastric secretions, is released from the duodenum in response to low ph (table 16. 2). Fatty acids and peptides in the duodenum initiate the release of the hormone cholecystokinin, which also inhibits gastric secretions (table. Acidic chyme (ph < 2. 0) in the duodenum also inhibits cns stimulation and initiates local reflexes that inhibit gastric secretion: compare and contrast the structure of the mucosal layers of the stomach and small intestine.
