GI - Anatomy (GI tract anatomy & histology)

Question 1

What are the 4 layers of the gut wall (inside to outside)?

Answer 1

Layers of gut wall (inside to outside - Think: “MSMS”): (1) Mucosa - epithelium (absorption), lamina propria (support), muscularis mucosa (motility) (2) Submucosa - includes Submucosal nerve plexus (Meissner) (3) Muscularis externa - includes Myenteric nerve plexus (Auerbach) (4) Serosa (when intraperitoneal)/adventitia (when retroperitoneal)

Question 2

What are the 3 parts of the GI mucosa, and for what function is it primarily used?

Answer 2

Mucosa - epithelium (absorption), lamina propria (support), muscularis mucosa (motility)

Question 3

What nerve plexus does the Submucosa contain? What is another name for this?

Answer 3

Submucosa - inclues Submucosal nerve plexus (Meissner)

Question 4

What nerve plexus does the Muscular externa contain? What is another name for this?

Answer 4

Muscularis externa - includes Myenteric nerve plexus (Auerbach)

Question 5

Is Serosa intraperitoneal or retroperitioneal? What is it called when it is in the other location?

Answer 5

Serosa (when intraperitoneal)/adventitia (when retroperitoneal)

Question 6

To where in the gut wall can ulcers extend? In what layer(s) are erosions found?

Answer 6

Ulcers can extend into submucosa, inner or outer muscular layer. Erosions are in the muscosa only.

Question 7

What are the frequencies of basal electric rhythm (slow waves) in each of the following GI areas: (1) Stomach (2) Duodenum (3) Ileum.

Answer 7

(1) Stomach - 3 waves/min (2) Duodenum - 12 waves/min (3) Ileum - 8-9 waves/min

Question 8

Draw a visual of the digestive tract layers, including and labeling the following: (1) Gland in submucosal layer (secretion) (2) Lamina propria (3) Inner circular muscle layer (motility) (4) Mesothelium (protective coating; reduction of friction) (5) Mesentery (binding of digestive tract to abdominal wall) (6) Muscularis mucosae (mucosal motility) (7) Myenteric plexus (control muscle contractions) (8) Outer longitudinal muscle layer (motility) (9) Serosa (support) (10) Subcomucosal plexus (control of secretory activity) (11) Submucosa.

Answer 8

See p. 337 in First Aid 2014 for visual

Question 9

What is the purpose of the mesentery?

Answer 9

Mesentery (binding of digestive tract to abdominal wall)

Question 10

What is the purpose of the mesothelium?

Answer 10

Mesothelium (protective coating; reduction of friction)

Question 11

What is the purpose of the outer longitudinal muscle layer?

Answer 11

Outer longitudinal muscle layer (motility)

Question 12

What is the purpose of the Gland in submucosal layer?

Answer 12

Gland in submucosal layer (secretion)

Question 13

What is the purpose of the Myenteric plexus?

Answer 13

Myenteric plexus (control muscle contractions)

Question 14

What is the purpose of the inner circular muscle layer?

Answer 14

Inner circular muscle layer (motility)

Question 15

What is the purpose of the submucosal plexus?

Answer 15

Submucosal plexus (control of secretory activity)

Question 16

What is the purpose of the Muscularis mucosa?

Answer 16

Muscular mucosae (Mucosal motility)

Question 17

What is the significant on histology of the esophagus?

Answer 17

Nonkeratinized stratified squamous epithelium

Question 18

What is the significant on histology of the stomach?

Answer 18

Gastric glands

Question 19

What is the significant on histology of the duodenum?

Answer 19

Villi and microvilli increase absorptive surface. Brunner glands (submucosa) and crypts of Lieberkuhn.

Question 20

What is the significant on histology of the Jejunum?

Answer 20

Plicae circulares and crypts of Lieberkuhn

Question 21

What is the significant on histology of the ileum?

Answer 21

Peyer patches (lamina propria, submucosa), plicae circulares (proximal ileum), and crypts of Lieberkuhn; Largest number of goblet cells in the small intestine

Question 22

What is the significant on histology of the colon?

Answer 22

Colon has crypts of Lieberkuhn but no villi, numerous goblet cells.

Question 23

In what part of the GI tract are brunner glands found? Be specific.

Answer 23

Duodenum - Brunner glands (submucosa)

Question 24

In what parts of the GI tract are crypts of Lieberkuhn found?

Answer 24

Duodenum, Jejunum, Ileum, & Colon

Question 25

What part of the small intestine has the largest number of globlet cells?

Answer 25

Ileum - Largest number of goblet cells in the small intestine