Midterm 2: Stomach Flashcards
Where is the stomach found? Where is the majority of the organ found?
Stomach is found between the esophagus and the duodenum of the small intestine. Posterior to left lobe of the liver and anterior to the primary tail of the pancreas and the left kidney.
The majority of the stomach is in the epigastric region (9 quadrant) or the upper left quadrant (4-quadrant) of the abdominal cavity.
What is the J-shaped intraperitoneal organ with lesser and greater curvatures as major anatomical boundaries?
Stomach
Where is the initial site of protein digestion?
In the stomach
What are the 4 regions of the stomach? Explain where they are located.
Fundus: Rounded portion superior-left to cardia
Cardia: Adjacent to gastroesophageal junction
Body: Central, large portion inferior to fundus
Pylorus: Proximal to opening into duodenum of small intestine. Contains pyloric sphincter.
Describe the pyloric sphincter’s location and function
Located at the gastroduodenal junction. Contains smooth muscle that is normally contracted and regulates chyme flow from stomach into the duodenum of small intestine.
Describe the greater and lesser curvature of the stomach
Lesser curvature: Shorter, concave, medial border of stomach with attachments to liver via hepatogastric ligament and lesser omentum
Greater curvature: Long, convex, lateral border of stomach with attachment for to the transverse colon inferiorly via the greater omentum
Describe rugae of stomach and its function
Wrinkles of the mucosa with submucosal cores on the internal surface.
Allows for distension (and increased luminal surface area, enlargement, dilation)
What kind of organ is the stomach? What does that mean?
Stomach is an intraperitoneal organ. This means that it is surrounded by peritoneum.
Layers of the stomach from inner to outer.
1) Mucosa
2) Submucosa
3) Muscularis
4) Serosa
Describe the innermost layer of the stomach
- Innermost layer is the Mucosa.
- Contains simple columnar epithelium.
- Surface and gastric pit lined with mucous-secreting cells that protect stomach lining.
- Has gastric glands that produce gastric juice (HCl + pepsin) that passes through the pit and into the stomach lumen.
- Can find parietal cells, chief (peptic) cells, and enteroendocrine cells here.
Function and location of parietal cells
Found in the mucosa layer of the stomach.
Secretes H+ and Cl- and intrinsic factors.
Secretion of H+ and Cl- forms HCl in gastric lumen which denatures proteins, or unravels their secondary and tertiary structure.
Intrinsic factor drives Vitamin B12 absorption in ileum of small intestine and is crucial for red blood cell formation and, when levels are deficient in the body → pernicious anemia
If the parietal cells in the mucosa of the stomach don’t secrete enough intrinsic factor, what could this cause?
Could cause pernicious anemia from the lack of B12 absorption in the small intestine
Describe function and location of Chief (peptic) cells?
Found in mucosa of the stomach.
secretes inactive pepsinogen which coverts to active pepsin in presence of HCl in the gastric lumen and hydrolyzes proteins.
What are enteroendocrine (neuroendocrine) cells? What are the enteroendocrine cells found in the mucosa of the stomach? Describe them
Enteroendocrine cells are specialized hormone-secreting cells.
- G cells secrete gastrin which increase gastric motility and regulation of gastric emptying of chyme into the duodenum along with stimulating H+ release from parietal cells. Constricts lower esophageal sphincter and relaxes pyloric to allow for movement of chyme into duodenum.
- ECL cells secrete histamine which stimulates H+ release from parietal cells.
- D cells secrete somatostatin which inhibits H+ release from parietal cells.
There are other enteroendocrine cells not discussed in this course apart from the cells those that secrete gherlin, which is involved in driving the hunger response.
What does the submucosa of the stomach contain?
blood vessels, nerves, lymphatic tissue, exocrine glands
