Histology

Question 1

What lines the oral cavity, oropharynx and laryngopharynx?

Answer 1

Squamous epithelium

Generally non-keratinised

Question 2

What lines the nasal cavity and nasopharynx?

Answer 2

Respiratory epithelium

Question 3

What is the histology of the anterior 2/3 of the tongue?

Answer 3

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

Question 4

What is the histology of the posterior 1/3 of the tongue?

Answer 4

Smooth stratified squamous epithelium
Lacks papillae (except for circumvallate)
Substantial lymphoid aggregates in the submucosa

Question 5

What are the four types of papillae which line the tongue?

Answer 5

Fungiform
Circumvallate
Foliate
Filiform (no tastebuds)

Question 6

What are the four major layers of the digestive tract (lumen outwards)?

Answer 6

Mucosa (Epithelium, Lamina propria, muscularis mucosae)
Submucosa
Muscularis externa (inner circular, outer longitudinal)
Serosa or Adventitia

Question 7

What occurs at the gastro-oesophageal junction?

Answer 7

Abrupt transition from stratified squamous epithelium of oesophagus to columnar epithelium of stomach

Question 8

What is the surface view of the stomach?

Answer 8

Relatively flat with holes (gastric pits)

Gastric glands at the bottom of the pits

Question 9

What lines the gastric pits of the stomach?

Answer 9

Surface mucous cells

Question 10

How are the cells in the gastric gland distributed?

Answer 10

Isthmus = Mostly parietal cells 
Neck = Mostly neck mucous cells and stem cells 
Base = Mostly chief cells, with a few parietal cells and neuroendocrine cells

Question 11

What is the role of the chief cells of the gastric glands?

Answer 11

Digestive enzyme secretion

Question 12

What is the role of the parietal cells of the gastric glands?

Answer 12

Hydrochloric acid production

Question 13

What is the mucosa of the cardia of the stomach like?

Answer 13

Deep gastric pits that branch into loosely packed, tortuous glands

Question 14

What is the mucosa of the body of the stomach like?

Answer 14

Shallow gastric pits with long straight gastric glands

Question 15

What is the mucosa of the pylorus of the stomach like?

Answer 15

Deep gastric pits with branched, coiled gastric glands at a higher density than in the cardia

Question 16

What is unusual about the muscular external of the stomach?

Answer 16

It contains an additional layer oblique to the circular and longitudinal muscle layers
Located internal to the circular layer
Aids the churning action of the stomach

Question 17

What occurs at the gastro-duodenal junction?

Answer 17

Abrupt transition from stomach mucosa to duodenal mucosa

Inner circular layer of smooth muscle thickens to form the pyloric sphincter

Question 18

What is the surface view of the small intestine?

Answer 18

Villi, with pits in between (Crypts of Lieberkhun)

Question 19

What is the histology of the duodenum?

Answer 19

Contains Brunner’s glands in the submucosa

These produce alkaline mucous to neutralise chyme from the stomach

Question 20

What is the histology of the jejunum?

Answer 20

Tallest villi, locate don circular folds of mucosa and submucosa (plicae circularis)

Question 21

What is the histology of the ileum?

Answer 21

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

Question 22

What are the cells of the small intestine epithelium?

Answer 22

Enterocytes 
Goblet cells 
Paneth cells 
Neuroendocrine cells 
Stem cells

Question 23

What are enterocytes?

Answer 23

Most numerous cells in SI epithelium
Tall columnar cells with brush border
Principle absorptive cells

Question 24

What are goblet cells?

Answer 24

Produce mucin to protect epithelium and lubricate passage of material

Question 25

What are Paneth cells?

Answer 25

Found at the base of the Crypts of Lieberkuhn Defensive function Regulate bacterial flora by secreting lysozyme and definsins

Question 26

What are neuroendocrine cells?

Answer 26

Produce hormones that contribute to control of secretion and motility (e.g. gastrin, CCK, VIP)

Question 27

What are stem cells?

Answer 27

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

Question 28

What are the two principal cells of the large intestinal epithelium, and what are their functions?

Answer 28

``` Absorptive cells = Removal of salts and thereby water Goblet cells = Secretion of mucus to lubricate the colon ```

Question 29

How are the cells of the large intestinal epithelium arranged?

Answer 29

Straight, tubular glands (crypts) which extend down into the muscular mucosae

Question 30

What is distinctive about the longitudinal muscle layer in the large intestine?

Answer 30

Not continous | Made of 3 muscular strips (teniae coli)

Question 31

What the histology of the appendix?

Answer 31

Similar to the colon Less abundant crypts Circular arrangement of lymphoid tissue in the submucosa and lamina propria Lymphiod tissue declines with age

Question 32

What occurs at the recto-anal junction?

Answer 32

Change from rectal mucosa to stratified squamous epithelium of the anal canal

Question 33

Where ar most of the neurones of the myenteric plexus found?

Answer 33

Between the two muscle layers of the muscularis externa

Question 34

What is the submucosal plexus?

Answer 34

Controls muscle of the muscularis mucosae ad helps regulate secretion in the epithelium

Question 35

Where is the sub mucous plexus found?

Answer 35

Submucosa

Question 36

What is the myenteric plexus?

Answer 36

Interconnected network of fibres that control gut motility