What are the four main regions of the stomach, and what is the function of the pyloric sphincter?
The four main regions of the stomach are the cardia (upper portion near the esophagus), fundus (bulging upper part), body (main J-shaped region), and pyloric part (which includes the pyloric antrum, canal, and sphincter). The pyloric sphincter acts as a valve that controls the passage of chyme from the stomach into the duodenum of the small intestine.
Describe the roles of the different cell types found in the gastric glands of the stomach mucosa.
The gastric glands contain mucus neck cells (produce acidic mucus), parietal cells (secrete hydrochloric acid and intrinsic factor), chief cells (produce pepsinogen and lipase), and enteroendocrine cells (release hormones such as gastrin). These cells collectively aid in protecting the stomach lining, digesting food, and regulating digestive processes.
What are the four main regions of the stomach and their general locations?
The four main regions are the cardia (upper portion near the esophagus), fundus (bulging upper part), body (main J-shaped region), and pyloric part (lower region leading to the small intestine).
What is the function of the pyloric sphincter in the stomach?
The pyloric sphincter acts as a valve that controls the passage of chyme from the stomach into the duodenum of the small intestine.
Name the four layers of the stomach wall from innermost to outermost.
The four layers are mucosa, submucosa, muscularis externa, and serosa.
What unique feature does the muscularis externa of the stomach have compared to the rest of the GI tract?
The muscularis externa of the stomach has an extra oblique muscle layer in addition to the circular and longitudinal layers.
What is the role of mucus neck cells in the gastric glands?
Mucus neck cells produce acidic mucus, which is different from the alkaline mucus produced by surface mucous cells.
Which cells in the gastric glands secrete hydrochloric acid and intrinsic factor, and what are their functions?
Parietal cells secrete hydrochloric acid (which denatures proteins and kills bacteria) and intrinsic factor (needed for vitamin B12 absorption).
What enzymes do chief cells produce and what are their roles in digestion?
Chief cells produce pepsinogen (which becomes pepsin to digest proteins) and lipase (which begins lipid digestion).
How does mechanical digestion occur in the stomach?
Mechanical digestion occurs through peristalsis, which mixes food with gastric juices to increase surface area for enzyme action.