Question

• Label on a diagram the four main regions of the stomach, its curvatures, and its sphincter
• Identify the four main types of secreting cells in gastric glands, and their important products
• Explain why the stomach does not digest itself
• Describe the mechanical and chemical digestion of food entering the stomach

Answer 1

The four types of cells in the stomach are, mucous cells, parietal cells, chief cells and endocrine cells. Mucous cells secretes mucous fluid, chief cells secrete pepsin which is a proteolytic enzyme, parietal cells secrete hydrochloric acid and endocrine cells called the G cell secrete gastrin.

3. ANSWER: The mucus layer secreted by the mucous cells in the stomach acts as a barrier for the hydrochloric acid in the lumen of stomach to react with the epithelium of the stomach. Hence it is called the gastric mucosal barrier.

4. ANSWER: Mechanical digestion in stomach is by peristalsis which helps in the churning of bolus and it mixes well with the acid and the enzymes in the stomach. Chemical digestion is carred by the enzymes like pepsin which is a proteolytic enzyme breaks down protein molecule into smaller peptides. These mechanical and chemical digestion converts the bolus into liquid form called the chyme.