Histo of Upper GI

Question 1

4 layers of the GI tract

Answer 1

Mucosa
Submucosa
Muscularis externa
Adventitia or serosa

Question 2

3 things in the mucosa

Answer 2

Epithelium
Lamina propria
Muscularis mucosae

Question 3

Functions of mucosa

Answer 3

Responsible for protection, absorption, and secretion

Question 4

GALT

Answer 4

Gastrointestinal associated lymphoid tissue
Can be diffuse or in Peyer’s patches (nodules)
Important because there is so much exposure to the external environment

Question 5

Submucosa

Answer 5

Dense irregular layer of connective tissue
Large blood vessels, lymphatics, nerves, and glands
Contains submucosal plexus on the inner surface of muscularis externa

Question 6

What 2 places are the submucosal glands found?

Answer 6

Esophagus
Proximal duodenum (Brunner's glands)

Question 7

Other name for:

1. Submucosal plexus
2. Myenteric plexus

Answer 7

1. Meissner’s plexus

2. Auerbach’s plexus

Question 8

Muscularis externa

Answer 8

Inner circular layer (unidirectional movement of food)
Outer longitudinal layer (shortens the tract)
Together they cause peristalsis

Question 9

How many layers of muscle in the stomach?

Answer 9

3

Oblique, circular, longitudinal

Question 10

Serosa

Answer 10

CT layer covered by thin layer of squamous cells (mesothelium)
Secretes serous fluid (lubricating to reduce friction)
Parts of GI tract that are free to move

Question 11

Adventitia

Answer 11

Outermost CT covering an organ/vessel
Lacks mesothelium
Binds structures together
Parts of GI tract that are relatively rigidly fixed

Question 12

5 places you would find adventitia

Answer 12

Oral cavity
Thoracic esophagus
Ascending colon
Descending colon
Rectum

Question 13

Where do you find the myenteric plexus

Answer 13

In CT between the inner circular and outer longitudinal layers

Question 14

Mucosa in stomach

Answer 14

Gastric pits and gastric glands

Mucosal glands secrete gastric juice (HCl, pepsin, rennin, lipase, mucus) into gastric pits

Question 15

Where do you find

1. Chief cells
2. Parietal cells
3. Surface mucous cells

Answer 15

1. Bottom on the gastric glands
2. Middle part
3. Surface

Question 16

What do
1. Chief cells
2. Parietal cells
secrete?

Answer 16

1. Pepsinogen 1 and 2
2. HCl and intrinsic factor
   The pepsinogen requires HCl to be activated

Question 17

Mucosa in small intestine

Answer 17

Villi with microvilli
Crypts (of Liberkuhn, aka glands)
Blood vessels
Lacteal
Simple columnar epithelium with goblet cells

Question 18

Amount of goblet cells vs enterocytes in small intestine vs colon

Answer 18

More enterocytes in small intestine (still pretty mushy)

More mucus cells in the large intestine (lubrication)

Question 19

What structures can you find in the 
1. Duodenum
2. Jejunum
3. Ileum
to help tell them apart?

Answer 19

1. Brunner’s glands
2. None
3. Peyer’s patches

Question 20

Functions of the large intestine

Answer 20

Fermentation of unabsorbed contents

Absorption of H2O, K+ and fat soluble vitamins