Digestive Tract Histology

Question 1

What is the epithelium covering the oral cavity, oropharynx and laryngopharynx?

Answer 1

Non-karatinized stratified squamous

Question 2

What is the epithelium covering the nasal cavity and nasopharynx?

Answer 2

Respiratory epithelium

Question 3

Describe the epithelium of the anterior 2/3rd of the tongue?

Answer 3

Stratified squamous epithelium, thin on ventral surface, thick and with papillae on the dorsal surface.

Question 4

Describe the epithelium of the posterior 1/3rd of the tongue?

Answer 4

Covered by smooth stratified squamous epithelium which, except for the circumvallate papillae, lacks papillae but does have substantial lymphoid aggregates in the submucosa

Question 5

What are the 4 different types of tongue papillae?

Answer 5

Filiform - no taste buds
Fungiform
Foliate
Circumvallate - vallate

Question 6

Describe the layers of the digestive tract?

Answer 6

Mucosa
Submucosa
Muscular externa
Serosa/adventitia

Question 7

Describe the mucosa further?

Answer 7

Mucosa

• epithelium - sits on basal lamina
• lamina propria - loose connective tissue
• muscular mucosal - thin layer of smooth muscle

Question 8

Describe the submucosa further?

Answer 8

Loose connective tissue

Question 9

Describe the muscular externa further?

Answer 9

Two thick layers of smooth muscle, an inner circular layer and outer longitudinal layer

Question 10

Describe the serosa/adventitia further?

Answer 10

Outer layer of connective tissue that either suspends the digestive tract or attached it to organs

Question 11

Describe what happens at the gastro-oesophageal junction?

Answer 11

There is an abrupt transition from stratified squamous epithelium of the oesophagus to columnar epithelium of the cardia of the stomach

Question 12

What are gastric pits?

Answer 12

Pits in the stomach, at the bottom of the gastric pit is a gastric gland.

Question 13

What are gastric pits lined by?

Answer 13

Surface mucous cells

Question 14

Describe what cells are in the gastric gland?

Isthmus
Neck
Base

Answer 14

Isthmus - mostly parietal cells
Neck - mostly mucous cells and stem cells
Base - mostly chief cells with a few parietal cells and endocrine cells

Question 15

What do chief cells produce?

Answer 15

Digestive enzymes

Question 16

What do parietal cells produce?

Answer 16

HCL

Question 17

Describe the mucosa differences in the different regions of the stomach?

Cardia
Body
Pylorus

Answer 17

Cardia - Deep gastric pits that branch into loosely packed, tortuous glands.

Body - Shallow gastric pits with long straight gastric glands.

Pylorus - Shallow gastric pits with long straight gastric glands.

Question 18

What is found in some areas of the stomach in relation to the muscular externa?

Answer 18

An extra layer is found oblique to the circular and longitudinal layers and is located internal to the circular layers

It aids the churning action of the stomach

Question 19

Describe the transition at the gasproduodenal junction?

Answer 19

From stomach mucosa to duodenal mucosa

Question 20

Describe the surface of the small intestine?

Answer 20

Finger like projections - villi and between the villi are pits called the crypts of lieberkuhn

Question 21

What type of glands does the duodenum contain?

Answer 21

Brunners glands in the submucosa

Question 22

What is the ilium characterised by?

Answer 22

Aggregations of lymphoid follicles called Peyer’s patches found in the submucosa and sometimes extending into the lamina propria

Question 23

What do the Brunner’s glands do int he duodenum?

Answer 23

They are stimulated by the presence of chyme and they produce a thin, alkaline mucous to neutralise the chyme

Question 24

Where are Peyer’s patches most commonly found?

Answer 24

In the Ileum

Question 25

What are the two principle types of cells found in the large intestine?

Answer 25

Absorptive cells - for removal of salts and water | Goblet cells - for the secretion of mucus to lubricate the colon

Question 26

How are the 2 principle types of cells in the large intestine arranged?

Answer 26

In straight, tubular glands, referred to as crypts that extend down to the muscular mucosae

Question 27

Describe the outer longitudinal smooth muscle of the large intestine?

Answer 27

It is found in 3 muscular distinct strips called teniae coli

Question 28

Describe the structure of the appendix?

Answer 28

Similar to the rest of the colon - crypts are less abundant

Question 29

Describe the transition at the rectoanal junction?

Answer 29

Mucosa of the rectun to the stratified squamous epithelium of the anal cancel

Question 30

Where do the neurones in the myenteric plexus live?

Answer 30

In the layers of the muscles of the muscular externa

Question 31

Where do the neurones in the submucosal plexus live?

Answer 31

In the submucosa

Question 32

What 2 plexus make up the ENS?

Answer 32

myenteric plexus and submucosal plexus

Question 33

What is the function of the submucosal plexus?

Answer 33

To control the muscle of the muscular mucosa and also help regulate secretion in the epithelium

Question 34

What is the function of the myenteric plexus?

Answer 34

Controlling gut motility

Question 35

What do the enter-endocrine cells break down into?

Answer 35

Different cells, such as K, G, I, S cells

Question 36

What do I cells secrete?

Answer 36

CCK and they are located in the duodenum and jejunum. They modulate bile secretion, exocrine pancreas secretion, and satiety

Question 37

What to G cells secrete?

Answer 37

Gastrin, and stimulate gastric acid secretion found in the stomach