Histology

Question 1

What lines the oral cavity, the oropharynx and the laryngopharynx?

Answer 1

stratified squamous epithelium

generally not keratinized

Question 2

What lines the nasal cavity and nasopharynx?

Answer 2

respiratory epithelium

Question 3

Describe the posterior third of the tongue?

Answer 3

smooth stratified squamous epithelium
lacks papillae but does have substantial lymphoid aggregates in the submucosa
does have the circumvallate papillae

Question 4

Describe the anterior two thirds of the tongue?

Answer 4

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

Question 5

What are the four types of papillae on the tongue?

Answer 5

Fungiform
Circumvallate
Foliate
Filiform (no tastebuds – occupy much of dorsal surface)

Question 6

What are the four layers of the digestive tract?

Answer 6

Mucosa
Submucosa
Muscularis Externa
Serosa or adventitia

Question 7

Name the 3 parts 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

Describe the submucosa?

Answer 8

loose connective tissue

Question 9

Describe the muscularis externa?

Answer 9

two thick layers of smooth muscle: an inner circular layer and an outer longitudinal layer

Question 10

Describe the serosa/adventitia?

Answer 10

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

Question 11

What type of glands are found in the oesophagus?

Answer 11

submucosal glands

Question 12

Describe the gastro-oesophageal junction?

Answer 12

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

Question 13

What are the holes in the flat surface of the stomach called?

Answer 13

gastric pit

Question 14

What are found at the bottom of gastric pits?

Answer 14

gastric glands (7 of them)

Question 15

What are gastric pits lined with?

Answer 15

surface mucous cells

Question 16

What are the four sections of the gastric glands? and which type of cells are at each section?

Answer 16

pit = surface mucosal cells
isthmus = parietal cells and mucous neck cells
neck = mucous neck cells and enteroendocrine cells and parietal cells
base = chief cells, parietal cells and enteroendocrine cells

Question 17

What does the chief cells of gastric glands do?

Answer 17

secrete digestive enzymes

Question 18

What does the pareital cells of gastric glands do?

Answer 18

produce hydrochloric acid

Question 19

What are the 3 different stomach regions?

Answer 19

Cardia
Body
Pylorus

Question 20

How does the mucosa differ in each region?

Answer 20

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

Body: Shallow gastric pits with long straight gastric glands.

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

Question 21

What is unusual about the muscularis externa in the stomach?

Answer 21

Contains an additional layer

• located internal to the circular layer
• aids the churning action

Question 22

What is the transition at the gastroduodenal junction?

Answer 22

transition from stomach mucosa to duodenal mucosa

The inner, circular layer of smooth muscle is markedly thickened to form the pyloric sphincter

Question 23

What are between the bases of adjacent villi? (in the small intestine)

Answer 23

crypts of Lieberkuhn

Question 24

How are the duodenum, jejunum and ileum characterised?

Answer 24

Duodenum: Contains Brunner’s glands in the submucosa

Jejunum: Tallest villi, located on permanent circular folds of the mucosa and submucosa, the plicae circularis.

Ileum: aggregations of lymphoid follicles called Peyer’s patches found in the submucosa and often extending into the lamina propria.

Question 25

Name and briefly describe the cells of the small intestine epithelium?

Answer 25

Enterocytes: most numerous cells, are tall columnar cells with a brush border and are the principle absorptive cell. Goblet cells: Produce mucin to protect epithelium and lubricate passage of material. Paneth cells: Found at the base of the crypts of Lieberkuhn, they have a defensive function and have a role in regulating bacterial flora (secrete lysozyme and definsins). Enteroendocrine (Neuroendocrine) cells: Produce hormones that contribute to the control of secretion and motility (e.g. gastrin, cholecystokinin (CCK), vasoactive intestinal peptide (VIP)) Stem cells: Found at the base of the crypts of Lieberkuhn, they divide to replenish epithelium.

Question 26

Describe Brunners glands?

Answer 26

In the duodenum | When stimulated by the presence of chyme they produce alkaline mucous to neutralise chyme

Question 27

What are the two principle cells of the large intestine epithelium?

Answer 27

Absorptive cells: For removal of salts and thereby water. | Goblet cells: For the secretion of mucus to lubricate the colon

Question 28

Describe the structure of absorptive and goblet cells?

Answer 28

These are arranged in straight, tubular glands, referred to as crypts, that extend down to the muscularis mucosae.

Question 29

What is the outer smooth muscle referred to in the large intestine?

Answer 29

teniae coli | - not continuous

Question 30

What is different about the appendix to the colon?

Answer 30

crypts are far less abundant | - normally a circular arragnement of lymphoid tissue

Question 31

Describe the rectoanal junction?

Answer 31

between the mucosa of the rectum and the stratified squamous epithelium of the anal canal. The 2-3cm long anal canal is then continuous with the stratified squamous epithelium of the surrounding skin.

Question 32

What network of fibres controls gut motility?

Answer 32

myenteric plexus

Question 33

What network of neurons controls the muscle of the muscularis mucosae?

Answer 33

submucosal plexus