29 - GI Histology I Flashcards Preview

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Flashcards in 29 - GI Histology I Deck (43)
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1

What are the four main layers (from internal to external) of the wall of the GI tract?

- Mucosa
- Submucosa
- Muscularis externa
- Serosa

2

Describe the mucosa of the GI tract

Mucosa includes...
a. Epithelium resting on a basal lamina – proximal and distal segments are stratified squamous, nonkeratinized, the rest of the tube is simple columnar
b. Lamina propria
c. Muscularis mucosae

Stratified squamous, nonkeratinized ***

3

What is in the lamina propria of the mucosa of the GI tract?

Lots of glands - very glandular in nature

4

Describe the muscularis mucosae of the mucosa of the GI tract

- Inner circular
- Outer longitudinal

Helps in the digestive process

5

Describe the serosa

Adventitia is associated with some segments of the GI tube

There are regional differences

6

What are the two enteric nerve plexuses?

- Submucosal (Meissner’s) plexus
- Myenteric (Auerbach’s) plexus

7

Describe the submucosal (Meissner’s) plexus

Parasympathetic postganglionic neurons and their processes and sympathetic postganglionic fibers; regulates the activity of the muscularis mucosae and the secretory activity of glands

*** peristalsis and gland secretion***

8

Describe the myenteric (Auerbach’s) plexus

Parasympathetic postganglionic neurons and sympathetic postganglionic fibers; regulates the activity of the muscularis externa

*** muscularis externa ***

9

Describe the layers of the esophagus

- Mucosa
- Submucosa
- Muscularis
- Outer connective tissue layer

10

Describe the mucosa of the esophagus

Epithelium and basal lamina
- Stratified squamous, nonkeratinized
- Protection against coarse-textured foods

Lamina propria - Esophageal cardiac glands

Muscularis mucosae

11

Describe the submucosa of the esophagus

Submucosa contains esophageal glands secrete mucus

12

Describe the three sections of the muscularis externa

i. Proximal 1/3 of esophagus – skeletal muscle
ii. Middle 1/3 of esophagus - Mixture of skeletal and smooth muscle
iii. Distal 1/3 of esophagus - Smooth muscle

13

What are the two layers of the outer connective tissue layer?

- Adventitia
- Serosa

14

What else is found in the esophagus?

Enteric nerve plexus

15

Describe esophageal varices

- Caused by hepatic portal hypertension
- Caused by cirrhosis of the liver
- You will see dilation of arteries with bulging varices
- On x-ray, there will be a rough appearance

16

Describe squamous cell carcinoma in the esophagus

Most common to develop carcinoma of the esophagus in the middle 1/3 of the esophagus

17

Describe Barrett's esophagus

- Stratified squamous epithelium (normal) changes to simple columnar epithelium with mucus producing cells
- This is done in response to acid reflux to protect the epithelium from
- For diagnosis, you need to see goblet cells (mucus producing cells)
- Known as metaplasia
- Barrett's is not reversible
- Can progress to adenocarcinoma of the esophagus, so Barrett's patients need to be monitored
- Adenocarcinoma occurs most commonly in the distal 1/3 of the esophagus due to its association with Barrett's

18

Describe the lymphatics of the esophagus

- Esophagus is well endowed with intramural lymphatic channels that anastomose
- Lymph flow in the upper 2/3 is usually upward, whereas lymph flow in the lower 1/3 tends to be downward
- We only see lymphatic metastasis if the cancer of the esophagus spreads to the submucosa where the lymph flow

19

What are the four regions of the stomach?

- Cardia
- Fundus
- Body
- Pylorus

20

What are rugae?

- Longitudinal folds in the undistended stomach
- Mucosa and submucosa form the folds

21

Describe the layers of the stomach

- Mucosa
- Submucosa
- Muscularis externa
- Serosa

22

Describe the mucosa of the stomach

- Surface epithelium - simple columnar, mucous cells
- Gastric pits are formed by the invagination of the surface epithelium into the lamina propria
- Glands empty into the gastric pits
- Gland regions: isthmus, neck, and base

23

Describe the muscularis externa of the stomach

- Inner oblique layer of smooth muscle
- Middle circular layer of smooth muscle - thickened at the pylorus
- Outer longitudinal layer of smooth muscle

24

What regional differences are seen in the cardia of the stomach?

- Short gastric pits
- Long glands in the lamina propria
- Simple or branched tubular glands
- Surface lining, mucous, regenerative, and DNES cells
- Few parietal cells

25

What regional differences are seen in the fundus and body of the stomach?

- Gastric pits become slightly longer
- Gastric glands are still long
- Branched tubular glands fill the lamina propria
- Isthmus region of gland
- Neck region of the gland
- Base region of the gland

26

What is the important "take home" message of the isthmus region of the glands?

***

This is the "stem cell niche" of the stomach - REGENERATIVE cells

Rapid turnover of cells - they replace ALL other cell types as they die off

***

27

What is the important "take home" message of the neck region of the glands?

***

This is where the parietal cells are - HCl secretion

Intrinsic factor is also secreted here

***

28

Describe the cells of the base region of the gland

Contains many chief (zymogenic) cells - pepsinogen

Only a few parietal cells and some mucus cells

29

Describe the regional differences seen in the pylorus of the stomach

- Deep gastric pits
- Short glands
- Branched tubular glands
- Surface lining, mucous, regenerative cells; a few parietal cells
- Enteroendocrine cells

30

What are all the cells we see in the gastric gland?

- Parietal cell
- Chief cell
- Enteroendocrine cell
- Smooth muscle fibers from the muscularis mucosae
- G cell