GI 2

Question 1

Stomach

Answer 1

expandable part of GI tract that lies beneath the diaphragm Functions: Storage and digestion of food and regulation of GI function

Question 2

Rugae

Answer 2

The folds of mucosa and submucosa that allow for the distensible feature of the stomach

Question 3

Digestion in Stomach

Answer 3

The stomach secretes HCl and digestive enzymes including pepsin and lypase to break down proteins and trigylcerides

Question 4

How does the stomach regulate GI functions?

Answer 4

Secretion of hormones (eg- gastrin) by enterendocrine cells

Question 5

Regions of the Stomach

Answer 5

Cardiac Region- located near the esophageal orifice and conatins cardiac glands Fundic Region (inlcudes body)- largest part containing fundic glands Pyloric Region- part proximal to pyloric sphincter containing pyloric glands

Question 6

Layers of the stomach

Answer 6

mucosa, submucosa, muscularis externa, serosa

Question 7

Submucosa of Stomach

Answer 7

dense irregular CT containing blood plexus (penetrates mucosa) and nerve plexus (Meissner’s). This layer contains NO GLANDS

Question 8

Muscularis Externa of the Stomach

Answer 8

3 layers of smooth muscle: Inner oblique layer, middle circular layer, and outer longitudinal layer. Auerbach’s plexus (myenteric nerve plexus) is located between the middle and outer layers of muscle.

Question 9

Serosa

Answer 9

Mesothelium and thin layer of subserosal CT; makeup same as reg alimentary canal

Question 10

malignant tumors of stomach

Answer 10

rather common, derived of surface epi cells in assoication with intestinal metaplasia or of glandular epi. Carcinomas are early if they only penetrate submucosa or late if they penetrate muscularis externa or further. The stage directly correlates to outlook of disease.

Question 11

Muscularis Mucosae of the Stomach (This is still part of the Mucosa)

Answer 11

continuous sheet of smooth mscle with 2-3 layers oriented orthogonally- both circular and longituinal

Question 12

Lamina Propria of Stomach

Answer 12

loose CT. scant and restricted to space b/n gastric pits and glands. Contains Immune elements like lymphocytes, plasma cells, and MΦ

Question 13

Pyloric Glands of stomach

Answer 13

in pyloric antrum serving to produce mucus that protects pyloric mucosa. They are branch tubular glands of mucus secretory cells. The gastric pits are often very deep and extend through half the depth of the mucosa. Enteroendocrine cells commonly found interspersed within glandular epithelium.

Question 14

Cardiac Glands of Stomach

Answer 14

limited to narrow ring surrounding the esophageal orifice. Serve to produce mucus htat contributes to gastric juice and protect esophageal epi against acid reflux. Branched tubular glands of mucus-secreting cells with basally flattend nuclei and granular cytoplasm. They lack parietal and cheif cells, which can differentiate them from Fundic glands. To diff from pyloric, note these glands only extend to half the depth of the mucosa. They also half interspersed enteroendocrine cells.

Question 15

Progenitor cells

Answer 15

Mostly located in the isthmus of the gland and serve to replace surface mucous cells and fundic gland cells (parietal, chief, mucous neck, and enteroendocrine cells). Short 3-5 day lifespan as compared to fundic gland cells which live 6-8 months

Question 16

Enteroendocrine Cells

Answer 16

Mostly concentrated at base of gland. Secrete product into lamina propria. Secrete gastrointestinal hormones to regulate functioning of alimentary canal. (including gastrin, ghrelin.) Rest on basement membrane and form microvilli that reach lumen of gland. Filled with membrane bound secretory granules in basilar part of cell.

Question 17

Gastrin

Answer 17

stimulates gastric acid secretion

Question 18

Ghrelin

Answer 18

stimulates appetite and hunger perception

Question 19

What can loss of Paritel Cells cause? When would you expect to see this?

Answer 19

pernicious anemia due to lack of intrinsic factor and thus B12 deficiency. B12 incorporates heme into hemoglobin. Patients with atrophic chronic gastritis.

Question 20

Gastric Ulcers

Answer 20

impairment of epithelial barrier in the stomach resulting in HCl destroying epi cells and lamina propria. Full penetration of gastric wall allows gastric content to pour into peritoneal cavity and peritonitis

Question 21

Mucous Neck cells

Answer 21

Mostly found within the neck of the gland. Serve to secrete soluble mucus, which is diff than the insoluble mucus produced by surface mucus cells. They are small and hard to ID. Small heterochromatic nucleus basally placed and cytoplasm of mucinogen granules giving it a frothy appearance.

Question 22

Gastic Chief Cells

Answer 22

Found at the base of the gland and serve to secrete pepsinogen that converts to pepsin (protelytic enzyme) when in contact with gastric juices. Typically Pt secreting cells. Abundant RER basally, basophilic apperance, apical secretory granules.

Question 23

Parietal Cells

Answer 23

Mostly found within the neck of gland but also occurs in base. Produce HCl to initiate digestion, convert pepsinogen to pepsin, and destroy bacteria. Produces intrinsic factor needed for absorption of b12 by intestine. LARGEST CELL IN FUNDIC GLAND. STAIN INTENSELY WITH eosin due to MITOCHONDRIA. DISTINCTIVE FEATURE: intracellular cannaliculi with microvilli. These are principal sites of HCL synth and secretion. HCl is toxic so is only produced when needed and in lumen of cannliculi. Apical membrane is nonsecreting stored in tubulovesicular system until stimulated to secrete HCl and fusion with apical membrane and microvilli formation.

Question 24

What 5 cell types are found in Fundic glands?

Answer 24

parietal cells, gastric chief cells, mucous neck cells, enteroendocrine cells, and progenitor cells

Question 25

What are the 3 segments of a Fundic gland?

Answer 25

Isthmus, neck and base

Question 26

Fundic Glands

Answer 26

Found throughout the stomach except small cardiac and pyloric region. They are branched tubular glands extending from muscularis mucosae to base of gastric pits. Straight at middle and apical part and coiled base. Isthmus is apical part adjacent to gastric pit. Base is bottom part adjacent to muscularis mucosae.

Question 27

Mucosa of Stomach

Answer 27

The lumen of stomach is lined with SCE of surface mucus cells. SMC apical part contains mucinogen granules and produce thick viscous gel coat that adhers to epi surface to protect from chyme abrasion. Within the lamina propria there are many glands unique to the region of stomach that open into gastric pits.