Esophagus and Stomach

Question 1

4 Layers of G-I Tract

Answer 1

Adventitia/Serosa
Muscluaris Externa (circular vs longitudinal)
Submucosa
Mucosa (epithelium, lamina propia, muscularis mucosae)

Question 2

3 Functions of GI-Tract

Answer 2

Barrier (mucosa/lymphocyte)
Absorption
Secretion (enzymes/mucous)

Question 3

Esophagus Function and Characteristics

Answer 3

transport food from oral cavity to stomach
- stratified squamous non-keratinized epithelium
- branched irregular lumen
- thick layer of muscularis externa
- submucosal mucous gland

Question 4

Divisions of Muscularis Externa in Esophagus

Answer 4

Striated muscle (voluntary control)
Both striated and smooth muscle
Smooth Muscle (involuntary control)

Question 5

Stomach Divisions

Answer 5

Spinchter (enlarged muscularis externa)
Cardiac – small pit + gland = mucus w/ bicarbonate ions
Body with Rugae (folds) – short pit + long gland
Pylorus – long pit + short gland = mucus secreted
Duodenum

Question 6

Stomach Characteristics

Answer 6

• simple columnar epithelium with surface mucous cells
• muscularis externa with 3 layers
  (inner oblique, middle circular, outer longitudinal)

Question 7

Cell Types in Pit and Gland of the Stomach

Answer 7

Surface Mucus Cell - mucin + bicarbonate
Stem Cell = ISTHMUS (divide into pit or gland)
Mucous Neck Cell - mucin to nervous stimuli
Parietal Cell - Intrinsic Factor + HCl (respond to gastrin)
Enteroendocrine Cell - gastrin
Chief Cell - Pepsinogen + Lipase

Pepsin = pepsinogen + HCl

Question 8

Parietal Cell Function, Composition, Appearance

Answer 8

• pump H+ and Cl- into gastric gland = HCl
• intracellular canaliculus (SA for ion pumps)
• lots of mitochondria (energy for ion pumps)
• central nucleus + eosinophilic

Question 9

Chief Cells Function, Composition, Appearance

Answer 9

• produce pepsinogen + lipase
• zymogen granules to package enzymes
• apical = eosin and basal = basophil

Question 10

Enteroendocrine Cell Function, Release

Answer 10

• secrete hormone Gastrin – stimulate parietal cell = HCl
• release into lamina propria NOT lumen of gland
• vesicles at basal edge

Question 11

Cell Renewal in Stomach

Answer 11

Isthmus = stem cells
- rapid surface-cell renewal (more exposure)
- slow gland-cell renewal

Question 12

Autonomic Nervous System on GI-Tract

Answer 12

Submucosal Plexus (in submucosa)
Myenteric Plexus (btwn circular + longitudinal layers of muscularis externa) – owl’s eye nuclei = ganglion cells