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
What is the muscularis externa?
The layer of the stomach found between the submucosa and the serosa. Contains 3 muscle layers arranged oblique, circular, and longitudinal going from most internal to external.
What layer of the stomach is most outer and is actually the visceral peritoneum?
Serosa layer.
What is a hiatal hernia? Symptoms and treatment.
Portion of stomach pushes up through the damaged diaphragm likely caused from injury.
Symptoms: Asymptomatic, burning sensation, GERD, heaviness
Treatment: Manage GERD, modify lifestyle factors, surgery
Describe gastritis. What is associated with acute and chronic. Its symptoms and treatment.
Acute or chronic inflammation of the gastric mucosa.
Food poisoning associated with acute. Gastric cancer associated with chronic.
Symptoms: Abdominal cramping, nausea, vomiting, belching, acid reflux, GI bleed.
Treatment: typically antacids to neutralize stomach acids
Describe gastric cancer.
Adenocarcinomas (many different subtypes).
More common in men over 60 years of age.
Risk factors: Obesity; diet high in processed/pickled foods, nitrosamines, red meat, salt and/or low in fruit/vegetable consumption; smoking; alcohol consumption; Heliobacter pylori infection (these gram-negative spirochete bacteria secrete the enzyme urease which converts urea to cytotoxic ammonia; ammonia can efficiently diffuse through the mucous layer and damage the underlying mucosa).
Symptoms: Weight loss (most common), epigastric pain, nausea, dysphagia, dark feces (melena)
What cells are found at the isthmus of a gastric gland?
parietal cells
What cells are found at the neck of a gastric gland?
neck mucosa cells, stem cells, and parietal cells
What cells are found at the base of a gastric gland
chief cells
parietal cells
neck mucosa cells
neuroendocrine cells (enteroendocrine)
What enteroendocrine cells stimulate H+ release from parietal cells? What hormone do they use to do so?
G and ECL cells
G: gastrin
ECL: histamine
What enteroendocrine cell inhibits H+ release from parietal cells? What hormone does it use to do so?
D cells. Somatostatin hormone.
What cells protect the gastric mucosa from being damaged by HCL? What do they secrete and what are they digested by?
Surface and neck mucosa cells. They secrete mucus and are auto-digested by their own digestive enzymes.
What makes gastric juice?
pepsin + HCL = gastric juice
Since digestion is driven by the parasympathetic system, what other hormone can stimulate HCl besides gastrin and histamine?
Acetylcholine
