Histology of GI system

Question 1

Layers of the oesophagus

Answer 1

Mucosa
Submucosa
Muscularis
Adventitia

Question 2

Submucosa of oesophagus

Answer 2

Submucosa - Dense irregular connective tissue containing larger blood vessels, lyphatic vessels, glands, nerve fibres and ganglion cells; nerve fibres and ganglion cells make up submucosal plexus

Question 3

Mucosa of oesophagus

Answer 3

stratified squamous epithelium; lamina propria; smooth muscle (longitudinally organised)

Question 4

Muscularis of oesophagus

Answer 4

Two muscle layers, an inner circular layer, and an outer longitudinal layer; myenteric plexus present between the two layers - nerve fibers and ganglion present

Question 5

3 regions of stomach

Answer 5

Cardiac region - near the oesophageal orifice, which contains the cardiac glands
Pyloric region - Proximal to the pyloric sphincter, contains the pyloric glands
Fundic region - largest part of stomach, situated between the cardia and pylorus and contain the fundic glands

Question 6

Stomach mucosa

Answer 6

SImple columnar epithelium
Openings called gastric pits that also have simple columnar epithelium
Surface mucous cells

Question 7

Fundic glands - gastric mucosa

Answer 7

Present throughout entire gastric mucosa

Extend from the bottom of the gastric pits to the muscularis mucosae

Question 8

Cells of the Fundic glands

Answer 8

Mucous neck cells
Chief cells
Parietal cells
enteroendocrine cells

Question 9

key identifying feature of chief cells

Answer 9

Very basophilic so appear darkly stained

Question 10

Key identifying feature of parietal cells

Answer 10

Eosinophilic staining - lighter stained

Question 11

WHat is the gastric mucosa

Answer 11

Limited to a narrow region of the stomach (cardia) that surrounds the oesophageal orifice
Mainly composed of mucous-secreting cells, with occasional interspersed enteroendocrine cells

Question 12

Pyloric Glands – Gastric Mucosa

Answer 12

Located in the pyloric antrum (between the fundus and the pylorus)

Cells in pyloric glands primarily mucosa secreting cells

Question 13

Gastric Muscularis

Answer 13

Traditionally described as containing an outer longitudinal layer, a middle circular layer, and an inner oblique layer
Myenteric (Auerbach’s) plexus located between the muscle layers

Question 14

What increases surface area of SI

Answer 14

plicae circulares - transverse folds that contain a core of submucosa
Villi - finger like projections of the mucosa that extend form surface into the lumen, consist of loos connective tissue covered by simple columnar epithelium
Microvilli - folds on the surface

Question 15

What is Villi

Answer 15

Projections of the mucosa
Consist of a core of loose connective tissue covered by a simple columnar epithelium
Smooth muscle cells derived from the muscularis extend into the villi

Question 16

Intestinal Glands

Answer 16

Simple tubular structures that extend from the muscularis mucosae through the thickness of the lamina propria

Composed of a simple columnar epithelium that is continuous with the epithelium of the villi

Question 17

5 types of cells in intestinal mucosa epithelium

Answer 17

Simple columnar absorptive cells
Goblet cells 
Paneth cells
Enteroendocrine cells
M cells

Question 18

Four regions of the large intestine

Answer 18

Ascending colon
Descending colon
transverse colon
Sigmoid colon

Question 19

3 sections of rectum

Answer 19

Colorectal zone – simple columnar epithelium
Anal transition zone – stratified squamous, cuboidal, or columnar epithelium
Squamous zone – stratified squamous epithelium