4. Histology of the Esophagus and Stomach

Question 1

What are the four general consistent layers to the G.I. tract?

Answer 1

1: Mucosa
2: Submucosa
3: Muscularis Externa
4: Serosa / Adventitia

Question 2

What determines the difference between serosa and adventitia?

Answer 2

Serosa is covered by peritoneum, adventitia is retroperitoneal.

Question 3

What is the lamina propria?

Answer 3

Vascularized loose connective tissue

Question 4

What is the function and location of the muscularis mucosae?

Answer 4

It is located in the mucosal layer of the G.I. tract, and is a thin layer of smooth muscle which squeezes mucosal glands.

Question 5

What is the submucosal layer comprised of?

Where do we see glands in the submucosal layer?

Answer 5

Dense irregular connective tissue with neurovasculature and lymphatics

in the esophagus and duodenum

Question 6

In which layer are the muscles which aid in gastrointestinal peristalsis located?

Answer 6

In the muscularis externa.

Question 7

Of the two layers to the muscularis externa – a circumferential and a longitudinal layer – which is the outer layer, and which is the inner layer?

Answer 7

The inner layer of the muscularis externa is circumferential

The outer layer of the muscularis externa is longitudinal

Question 8

Where are the neurovascular plexes located in the muscularis externa?

Answer 8

Between the inner circular and outer longitudinal layers of muscle.

Question 9

What nerves make up the parasympathetic portion of the extrinsic nervous system of the G.I.?

Answer 9

The vagus nerve – up to the splenic flexure

The pelvic splanchnics – after the splenic flexure

Question 10

Are the fibers from the vagus nerve and pelvic splanchnics presynaptic or postsynaptic?

Answer 10

They are presynaptic

Question 11

What nerves provide sympathetic autonomic innervation to the G.I.?

Answer 11

Branches from the greater, lesser, least, and lumbar splanchnic nerves.

Question 12

Where do the sympathetic nerves for the G.I. synapse?

Answer 12

The celiac, superior mesenteric, inferior mesenteric, and aorticorenal ganglia.

Question 13

What is the location and function of the plexus of Meissner?

Answer 13

The (submucosal) plexus of Meissner is located in the submucosa, and controls glandular secretion via control of the muscularis mucosae.

Question 14

What is the location and function of the myenteric plexus of Auerbach?

Answer 14

The myenteric plexus of Auerbach is located in between the layers of the muscularis externa and controls peristalsis.

Question 15

In terms of motility of the G.I., what would be the function of a presynaptic axon?

Answer 15

Preganglionic axons (of the parasympathetics) increase motility.

Question 16

Where are the cardiac esophageal glands located?

In which histological layer are they found?

Answer 16

The cardiac esophageal glands are located in the terminal portion of the esophagus (near the cardia of the stomach).

The cardiac esophageal glands are located in the lamina propria of the mucosa.

Question 17

How might submucosal glands of the esophagus be able to regulate the viscosity of their secretion?

Answer 17

They contain both mucus and serous cell types, and are drained by a single duct.

Question 18

What is Barrett’s esophagus?

Answer 18

Barrett’s esophagus is when GERD becomes chronic, and the stratified squamous epithelium of the esophagus becomes mucus-secreting simple columnar epithelium.

Question 19

What characterizes the gastroesophageal junction?

Answer 19

A drastic change in epithelium from stratified squamous epithelium of the esophagus, to the simple columnar epithelium of the stomach.

Question 20

Where do we find the cardiac, gastric, and pyloric glands of the stomach histologically?

Answer 20

In the lamina propria of the mucosa

Question 21

What are gastric pits?

Answer 21

Openings of the cardiac, gastric, and pyloric glands into the lumen of the stomach.

Question 22

What is different about the muscularis externa of the stomach?

Answer 22

It contains an external longitudinal layer, a middle circular layer, and an extra inner oblique layer.

Question 23

Histologically, what is the pyloric sphincter made of?

Answer 23

A thickening of the inner circumferential layer of the muscularis externa of the stomach

Question 24

Is a muscularis mucosae present in the stomach?

Answer 24

Yes, in some sections

Question 25

What is the function of the isthmus of the gastric pit/gland?

Answer 25

Is the location of undifferentiated stem cells, which mostly differentiate into the surface mucous cells of the gastric pit.

Question 26

What cell type is contained in the gastric pit?

Answer 26

Surface mucous cells

Question 27

What cell types are contained in the neck of a gastric gland?

Answer 27

Mucus neck cells

Enteroendocrine cells

Parietal cells

Question 28

What cell types are contained in the fundus of a gastric gland?

Answer 28

Chief cells

Enteroendocrine cells

Parietal cells (some)

Question 29

What is the difference between an “open” and “closed” enteroendocrine cell?

Answer 29

Open enteroendocrine cells have a thin protrusion of cytoplasm with microvilli that can receive signals from the lumen of the gland.

Closed enteroendocrine cells do not reach the lumen of the gland, and must be regulated by paracrine and neural mechanisms.

Question 30

What is different about the orientation of cardiac glands and gastric glands?

Answer 30

Cardiac glands are tubular, coiled, and less branched.

Question 31

What secretions are produced by cardiac glands?

Answer 31

Only mucous, as they lack parietal or chief cells. The mucus secreting cells are similar to what is found in the esophagus.

Question 32

What two glands of the stomach are coiled and tubular?

Answer 32

Cardiac glands and pyloric glands

Question 33

What region of the stomach has deep gastric pits, an increase in mucus secretion, and GALT?

Answer 33

The pyloric region of the stomach around the pyloric glands