Histology

Question 1

What type of epithelium is the oral cavity, oropharynx and laryngopharynx covered by

Answer 1

Generally non-keratinised (Except hard palate and gingiva) stratified squamous epithelium

Question 2

What type of epithelium is the nasal cavity and nasopharynx covered by?

Answer 2

Respiratory epithelium

Question 3

What type of epithelium covers the anterior 2/3rds of the tongue
How does this vary between the ventral and dorsal surface

Answer 3

Stratified squamous epithelium
Thin on ventral surface
Thick with papillae on the dorsal surface

Question 4

Epithelium on the posterior 1/3rd of the tongue

Answer 4

Smooth stratified squamous epithelium which lacks papillae, except the circumvallate papillae, but does have some lymphoid follicles in the submucosa

Question 5

What are the 4 types of taste buds present on the tongue?

Answer 5

Fungiform
Cicumvallate
Foliate
Filiform (no tastebuds - occupy much of the dorsal surface of the tongue)

Question 6

What are the 4 major layers of the digestive tract (from the oesophagus to the anal canal)

Answer 6

Mucosa (epithelium, lamina propria, muscularis mucosae)
Submucosa
Muscularis externa
Serosa or adventitia

Question 7

What are the 3 layers of the mucosa?

Answer 7

Epithelium (sits on a basal lamina)
Lamina propria (loose connective tissue)
Muscularis mucosae (thin layer of smooth muscle)

Question 8

What is the submucosa

Answer 8

Loose connective tissue

Question 9

What is the muscularis externa

Answer 9

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

Question 10

What is the serosa or adventitia

Answer 10

An outer layer of connective tissue that ether suspends the digestive tract or attaches it to other organs

Question 11

What happens in terms of the epithelium at the cardia of the stomach

Answer 11

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

Question 12

What are the holes in the surface of the stomach and what is at the bottom of these

Answer 12

Holes = gastric pits

There are 1-7 gastric glands at the bottom of these

Question 13

What are gastric pits lined by

Answer 13

Surface mucous cells

Question 14

In terms of the cells gastric gland, what does the pit contain mostly?
Isthmus?
Neck?
Base?

Answer 14

Pit = surface mucous cells
Isthmus = parietal cells
neck = neck mucous cells and stem cells
Base = chief cells (few parietal cells and neuroendocrine cells)

Question 15

What are chief cells of gastric glands?

Answer 15

digestive enzyme secreting cells

Question 16

What are parietal cells of gastric glands

Answer 16

HCl acid producing cells

Question 17

How does the mucosa of the stomach differ across the cardia, body and pylorus?

Answer 17

The cardia contains deep gastric pits that branch into loosely packed, tortuous glands
The body contains shallow gastric pits with long straight gastric glands
The pylorus contains deep gastric pits with branched, coiled gastric glands at a higher density than in the cardia

Question 18

What is unusual about the muscularis externa of the stomach?

Answer 18

It contains an additional oblique layer which located internal to the circular layer and aids in the churning action of the stomach

Question 19

What creates the pyloric sphincter?

Answer 19

The inner circular layer of smooth muscle is markedly thickened

Question 20

Epithelium of the small intestine

Answer 20

Simple columnar epithelium with villi and tubular glands

Question 21

Epithelium of the large intestine

Answer 21

Simple columnar epithelium with tubular glands

Question 22

What are the crypts called between the bases of adjacent villi in the small intestine?

Answer 22

Crypts of Lieberkuhn

Question 23

What makes the duodenum different from any other region of the GI tract

Answer 23

It contains glands within the submucosa called Brunner’s glands which when stimulated by the presence of chyme, produce a thin, alkaline mucous to neutralise the chyme

Question 24

What part of the small intestine has the tallest villi

Answer 24

The jejunum (located on the plicae circulars)

Question 25

What are the permanent circular folds on the mucosa and submucosa of the small intestine (except the first part of the duodenum) called?

Answer 25

Plicae Circularis (these are not just folds of the mucosa, but also contain submucosa)

Question 26

What are the cells of the small intestinal epithelium

Answer 26

``` Enterocytes Goblet cells Paneth cells Neuroendocrine cells Stem cells ```

Question 27

What are enterocytes

Answer 27

Most numerous cell in small intestinal epithelium Tall columnar cells with a brush border Principle absorptive cell

Question 28

What are goblet cells

Answer 28

Produce mucin to protect epithelium and lubricate passage of material

Question 29

What are paneth cells

Answer 29

Found at the base of the crypts of Lieberkuhn and have a defensive function and role in regulating bacterial flora (secrete lysozyme and definsins)

Question 30

What do neuroendocrine cells produce?

Answer 30

Hormones that contribute to the control of secretion and motility e.g. CCK, gastrin, VIP

Question 31

Purpose of stem cells in small intestinal epithelium

Answer 31

Found at the base of the crypts of Lieberkuhn | Divide to replenish the epithelium

Question 32

What does GALT stand for?

Answer 32

Gut associated lymphoid tissue - the gut has a substantial amount of lymphoid tissue associated with it

Question 33

What are Peyer's patches

Answer 33

Areas of relatively large aggregations of lymphoid tissue, particularly in the ileum

Question 34

What are the 2 principal cell types present in the epithelium of the large intestine

Answer 34

Absorptive cells - for removal of salts and thereby water Goblet cells - for the secretion of mucus to lubricate the colon (these are arranged in straight tubular glands referred to as crypts that extend down to the muscularis mucosae

Question 35

What is different about the outer, longitudinal smooth muscle in the large intestine

Answer 35

Is not continuous but instead found in 3 muscular strips called teniae coli

Question 36

What is different about the structure of the appendix compared to the rest of the colon

Answer 36

The crypts are far less abundant There is typically a circular arrangement of lymphoid tissue in the submucosa and often the lamina propria (the lymphoid tissue tends to decline with age)

Question 37

What type of epithelium does the anal canal have

Answer 37

Stratified squamous epithelium

Question 38

Where do most of the neurones of the enteric nervous system live? What is this interconnected of fibres called? What does it control?

Answer 38

In groups called ganglia between the 2 muscle layers that make the muscularis externa Myenteric plexus Gut motility

Question 39

Apart from the myenteric plexus, what other network of enteric neurones exist? Where is this found? What does it control?

Answer 39

Submucosal plexus Submucosa Controls the muscle of the muscularis mucosae and also helps regulate secretion in the epithelium