5. Esophagus/Stomach Histo

Question 1

The muscosa differs the most from region to region so it is important to look at this when trying to identify GI areas. What are the four layer of the tract from lumen to superficial?

Answer 1

mucosa
submucosa
muscularis externa
serosa (if has peritoneum)/adventitia (if no peritoneum)

Question 2

The mucosal layer has 3 components: simple columnar epithelium, lamina propria, and a thin layer of smooth muscle; muscularis mucosae. What is within the lamina propria? (4)

Answer 2

lymphatic nodules
lymphocytes
plasma cells
macrophages

Question 3

What is the function of the smooth muscle in the mucosal layer, the muscularis mucosae?

Answer 3

controls mobility of the mucosa/mucosal glands

Question 4

What layer of the GI tract consists of dense irregular CT with NV/lymphatics as well as glands (in esophagus and duodenum)

Answer 4

submucosal layer

Question 5

The muscularis externa assists in the movement of food. There are two layers of smooth muscle with NV bundles residing between layers. What are the two layers of smooth muscle and how do they constrict?

Answer 5

Inner circular layer: contraction constricts lumen

Outer longitudinal layer: contraction shortens tube

Question 6

What layer is it when the digestive tube is suspended by a mesentery/peritoneal fold covered in mesothelium?

Answer 6

Serosa layer

Question 7

There is extrinsic (para/sympathetic) and intrinsic (ENS) innervation in the GI. What is the parasympathetic innervation to the GI? (2)

Answer 7

Vagus nerve until splenic flexure
Pelvic splanchnic from splenic flexure on (presynaptic)
the ganglion on postsynaptic fibers are intramural

Question 8

Sympathetic innervation to the GI includes branches from the greater, lesser, least and lumbar splanchnics. What is the synapse and postsynaptic?

Answer 8

Synapse in prevertebral ganglia (celiac, Superior mesenteric, IM, aorticorenal)
Postsynaptic nerves travel to organs via plexuses

Question 9

What are the two plexuses of sensory and motor neurons linked by interneurons and where can they be found?

Answer 9

Submucosal plexus of meissner (submucosa)

Myenteric plexus of Auerbach (muscularis externa in between inner circular and outer longitudinal layers)

Question 10

What are the main functions of the submucosal plexus of meissner and the myenteric plexus of auerbach?

Answer 10

Submucosal: controls secretions of glands

Auerbach in muscularis externa: controls peristaltic contractions and movements of muscularis mucosae

Question 11

The preganglionic acons of the parasympathetic increase motility while the postganglionic acons of sympathetics do what?

Answer 11

DECREASE motility

Question 12

The esophagus has serosa or adventitia?

Answer 12

Both; Thoracic esophagus is adventitia, inferior to diaphragm is serosa

Question 13

Mucosal and submucosal glands produce a thin layer of mucus to lubricate the epithelium. What is each of the glands?

Answer 13

Cardiac esophageal glands in the lamina propria near the cardia of the stomach
Submucosal glands in the submucosa

Question 14

The mucosa of the esophagus is nonkeratinized stratified squamous epithelium, with number folds. What is only present in the lower segment?

Answer 14

muscularis mucosae d/t increase in cardiac glands

Question 15

The submucosa of the esophagus has dense ireg CT with blood vessels called submucosal venous plexuses. What occurs when there is an increase in pressure here?

Answer 15

Can cause esophageal varices which are dilations of the veins

Question 16

What is the hallmark of the muscularis layer of the esophagus? (3)

Answer 16

upper third: skeletal muscle
Middle third: skeletal and smooth muscle
lower third: smooth muscle

Question 17

What is the epithelial change from the esophagus to the stomach at the gastroesophageal junction?

Answer 17

it goes from nonkeratinized stratified squamous to simple columnar with pits and glands

Question 18

There is a UES and a LES in the esophagus. GERD or gastroesophageal reflux disease causes inflammation, ulceration and dysphagia (hard to swallow). What is a sign of GERD/Barrett’s esophagus?

Answer 18

when the nonkeratinized stratified squamous epithelium in the transition zone from E to stomach becomes columnar mucus-secreting/glandular!

Question 19

The orad area is the fundus and upper part of the body of the stomach which relaxes during swallowing. What is the caudad area of the stomach?

Answer 19

lower portion of the body and pyloric antrum which helps with regulation of gastric emptying

Question 20

Rugae are longitudinal folds of the gastric mucosa and submucosa, whose purpose is?

Answer 20

to increase friction in the stomach and assist in breaking down food

Question 21

The mucosa of the stomach has simple columnar epithelium with a lamina propria containing glands (gastric, cardiac, pyloric) depending on the location in the stomach. What does the muscularis mucosae do?

Answer 21

facilitates the release of gastric gland secretions

Question 22

What is different about the muscularis externa in the stomach? **Hallmark

Answer 22

There are three layers of smooth muscle, olique, circular then longitudinal

Question 23

The circular muscle layer thickens in the pyloric region forming?

Answer 23

the pyloric sphincter

Question 24

Fundic/Gastric glands are located everywhere except where pyloric and cardiac glands are. They are simple branches tubular glands which extend from gastric pits to muscularis mucosae. What are the 3 regions?

Answer 24

Isthmus: between gastric pit and gland
Neck: narrow, llong
Fundus: short and wide at base

Question 25

The neck of fundic glands has mucous cells, parietal cells and enteroendocrine cells while the fundus region at the base has cheif cells, enteroendocrine cells and some parietal cells. What type of cells can be found in the gastric pit and isthmus?

Answer 25

Pit: Surface mucous cells (goblet like)
Isthmus: contain dividing and undifferentiated cells to make new mucous cells

Question 26

Both the surface and neck mucous cells form a mucous layer containing 95% water and 5% mucin. What does it form and what does it neutralize?

Answer 26

Forms an insoluble gel that attaches to the surface of gastric mucosa which neutralizes the microenvironment to an alkaline pH

Question 27

What cells contain zymogen granules in the apical region such as pepsinoge, which is released into the lumen and converted into pepsin by the acidic environment, its release is stimulated by feeding?

Answer 27

Cheif cells (base region of fundus in fundic/gastric gland)

Question 28

Parietal cells are mainly in the neck of fundic glands. They produce hydrochloric acid and intrinsic factor that binds B12. What are two other distinctive features?

Answer 28

abundant mitochondria for ATP to pump H+

Intracellular canaliculus

Question 29

What type of cells are prevalent at all levels of the fundic gland but more at the base, which has open and closed cells?

Answer 29

Enteroendocrine Cells

Question 30

Closed enteroendocrine cells are small cells that rest on the basal lamina and are not exposed to the lumen, controlled by neural/paracrine mechanisms. What are open enteroendocrine cells?

Answer 30

Open cells have thin extensions with microvilli exposed to the lumen, controled by chemoreceptors to release HORMONES

Question 31

What are three main peptide hormones that are produced by enteroendocrine cells?

Answer 31

Gastrin
Somatostatin
Ghrelin

Question 32

Gastrin is produced by G cells in the pyloric antrum and stimulates production of HCl by parietal cells. Somatostatin is produced by D cells and inhibits gastrin. What about ghrelin?

Answer 32

Produced only in the gastric fundus and binds to receptor in pituitary to stimulate GH secretion, increases hunger

Question 33

Cardiac Glands are located in the cardia of the stomach which surrounds the esophageal orifice. The glands are tubular, coiled and branched and only have mucus secreting cells. What is its HALLMARK?

Answer 33

They appearr circular and oblique in sections, with a single pit

Question 34

Pyloric glands are branched, coiled and tubular between fundus and pylorus and are line with mucus secreting cells (large/pale). What can be seen sometimes in the lamina propria?

Answer 34

GALT/lymph nodules and sometimes enteroendocrine and parietal cells