Alimentary System I - Esophagus and Stomach

Question 1

Name the four layers of GI walls.

Answer 1

1. Mucosa
2. Submucosa
3. Muscularis externa
4. Adventitia/serosa

Question 2

Describe the composition of the mucosa layer.

Answer 2

3 layers

1. Epithelium
2. Loose CT called the lamina propria
3. Smooth muscle layer called the muscularis mucosae

Question 3

What type of tissue makes up the submucosa?

Answer 3

Loose or dense CT

Question 4

What type of muscle is usually found in the muscularis externa of the esophagus? How is the muscle organized? What is the one exception?

Answer 4

Smooth muscle except in the upper third of the esophagus which is skeletal muscle, and the middle third is a mix of skeletal/smooth muscle. Organized into orthogonal layers for peristalsis.

Question 5

Where does serosa occur?

Answer 5

Where the organ is covered with mesothelium.

Question 6

What two organs does the esophagus connect?

Answer 6

The oropharynx to the stomach.

Question 7

What is responsible for preventing acid reflux?

Answer 7

The esophogeal sphincter.

Question 8

What cell type is found in the epithelium of the esophagus?

Answer 8

SSNKE.

Question 9

Name the layers of the esophagus.

Answer 9

Epithelium, lamina propria, muscularis mucosa, submucosa, muscularis externa (with serosa connected to mesothelium where the esophagus enters the stomach).

Question 10

What glands are unique to the submucosa of the esophagus? What epithelial cell type is found here?

Answer 10

Submucosal esophogeal glands, which secrete lubricant to protect the mucosa from food passing through. Stratified cuboidal epithelium.

Question 11

What proteins do the secretions of the submucosal esophogeal glands contain?

Answer 11

Lysozyme and epidermal growth factor (EGF)

Question 12

What epithelial cell type is found in the stomach?

Answer 12

Simple columnar.

Question 13

What is the area called where the epithelial cells of the esophagus transition to the columnar cells of the stomach?

Answer 13

The squamocolumnar junction.

Question 14

Name the three stomach regions.

Answer 14

Cardia, fundus/body, pyloris.

Question 15

Describe the gastric glands of the cardia.

Answer 15

Short pits, short glands.

Question 16

Describe the gastric glands of the fundus/body.

Answer 16

Short pits, long glands.

Question 17

Describe the gastric glands of the pyloris.

Answer 17

Long pits, short glands.

Question 18

What is the primary function of the muscularis externa layers of the fundus/body?

Answer 18

Churning food.

Question 19

What does gastrin do? What secretes it?

Answer 19

It stimulates digestion by increasing gastric motility and secretion of HCl. It is secreted by enteroendocrine glands found in all three stomach regions.

Question 20

What cells are found on the surface throughout the stomach? What is their function?

Answer 20

Surface mucous cells. Function is to secrete protective mucous.

Question 21

How do surface mucous cells secrete mucus?

Answer 21

They store mucin granules in their apical regions and release them through exocytosis once stimulated.

Question 22

How do surface mucous cells stain?

Answer 22

Poorly with H&E but well with PAS.

Question 23

Name three cells that are found in fundic region glands.

Answer 23

1. Mucous cells
2. Parietal cells
3. Chief cells

Question 24

What are the two major functions of parietal cells?

Answer 24

1. Produce HCl

2. Produce intrinsic factor

Question 25

Are parietal cells eosinophilic or basophilic? Why?

Answer 25

Eosinophilic because they have abundant mitochondria for proton pumps.

Question 26

By which system do parietal cells increase their surface area for greater H+ secretion?

Answer 26

Complex tubulovascular system.

Question 27

What is an intracellular canaliculus?

Answer 27

The system by which parietal cells increase surface area for greater acid production after a meal.

Question 28

Where are chief cells found and what do they do?

Answer 28

Found deep within gastric glands of the fundic region. They produce pepsinogen.

Question 29

How do chief cells stain? Why?

Answer 29

Basophilic due to abundant ribosomes.

Question 30

Where are mucous neck cells found and what do they do? How are they best visualized?

Answer 30

Found in the neck of gastric glands, they protect glands from the acid pH and active pepsin. Must be stained with mucin stains, PAS.

Question 31

Intrinsic factor is important for absorption on which vitamin? Deficiency of this vitamin can lead to what disease?

Answer 31

B12. Deficiency can lead to Pernicious anemia.

Question 32

What is the esophogeal hiatus?

Answer 32

Where the esophagus enters the abdominal cavity.

Question 33

Compare Miessner's plexus and the Auerbach's plexus of the esophagus.

Answer 33

Miessner's is located in the submucosa, and Auerbach's is located just outside the circular muscle layer in the muscularis externa.

Question 34

Is the esophagus covered with serosa?

Answer 34

Just for a short bit before it enters the stomach. The rest is adventitia!!