Histology

Question 1

What covers the nasopharynx and nasal cavity

Answer 1

Respiratory epithelium

Question 2

What covers oro and layngopharynx

Answer 2

Stratified squamous epitelium (non-keratenized)

Question 3

Anterior tongue is covered by

Answer 3

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

Question 4

Histology of posterior tongue

Answer 4

Smooth stratified squamous epithelium which only has circumvallate papillae and large lymphoid aggregate in submucosa

Question 5

Papillae of tongue

Answer 5

Most of the dorsal surface if covered by filiform papillae. Fungiform are found interspaced. In front of the sulcus terminalis lies a v-shaped circumvallate papillae. Laterally lie the foliate papillae.

Question 6

Function of serous gland in papillae

Answer 6

The papillae are arranged in a moat like structure. The serous glands secrete a watery fluid that helps wash this moat and make ready for subsequent tasting.

Question 7

Characteristic of posterior 1/3rd of tongue

Answer 7

Lots of lymphoid tissue with some lymphoid follicles

Question 8

Layers of digestive tract, inside to out

Answer 8

Mucosa, submucosa, muscularis externa and serosa or adventitia

Question 9

Differentiate serosa and adventitia

Answer 9

Serosa is simple squamous epithelium, shiny and sparse layer of loose connective tissue. It covers external layers of organs. Adventitia is loose connective tissue that serves to hold organs in place. It oftens grades off into adjacent adventitia

Question 10

Parts of mucosa

Answer 10

Epithelium, lamina propriae and muscularis mucosae

Question 11

Parts of muscularis externa

Answer 11

Inner circular and outer longitudinal smooth muscles

Question 12

What is Barrett’s oesophagus

Answer 12

Metaplastic change in oesophagus from stratified squamous epithelium to simple columnar with goblet cells. This can lead to oesophageal adenocarcinoma

Question 13

What is the gastro-oesophageal junction

Answer 13

Point where stratified squamous epithelium of oesophagus transitions to columnar epithelium of cardia of stomach

Question 14

What can the layer of stomach cells be divided into

Answer 14

Pit, isthmus, neck, base

Question 15

Distribution of cells in gastric gland

Answer 15

Pit - Surface mucous cells
Isthmus - Parietal cells
Neck - Stem cells and neck mucous cells
Base - Chief cells with few parietal and neuroendocrine/enteroendocrine cells

Question 16

Parietal vs chief cells

Answer 16

Parietal - Called oxyntic cells, make HCl, mostly at isthmus, lots of mitochondria, histamine/gastrin and acetylcholine receptors
Chief cells - Have zymogen granules with pepsinogen, mainly at base

Question 17

Why do chief cells stain intensely

Answer 17

Due to presence of pepsinogen

Question 18

Mucosa in different regions of stomach

Answer 18

Cardia - Deep gastric pits that branch into loosely packed glands
Body - Shallow pits with long straight gastric glands
Pylorus - Deep gastric pits that branch, coiled at higher density than cardia

Question 19

Function of extra layer oblique internally to circular and longitudinal layer of muscularis externa

Answer 19

Churning action of stomach

Question 20

Modification at gastroduodenal junction

Answer 20

Inner circular layer of muscularis externa is thickened to form pyloric sphincter

Question 21

Pits in small intestine are called

Answer 21

Pits of Lieberkuhn

Question 22

Compare regions of small intestine

Answer 22

Duodenum - Has Brunner’s glands in submucosa
Jejunum - Tallest villi on circular folds of mucosa and submucosa, the plicae circularis
Ileum - Lymphoid aggregations called Payers patch in submucosa and lamina propria

Question 23

What are enterocytes

Answer 23

Tall columnar cells with a brush border appearance, main absorptive cells

Question 24

Function of goblet cells in small intestine

Answer 24

Secrete mucin to protect epithelium and lubricate passage of material

Question 25

Function of paneth cells in small intestine

Answer 25

At base of crypts of Lieberkuhn, secrete lysozyme and defensins (bacteriocidals) and regulate bacterial flora

Question 26

Function of enteroendocrine cells (neuroendocrine)

Answer 26

Secrete hormones such as gastrin, CCK, vasoactive intestinal peptide (VIP) to control secretion and motility

Question 27

Function of Brunners gland in duodenum

Answer 27

Chyme stimulates this to produce a thin, alkaline mucous to neutralise the chyme. Present in submucous

Question 28

What are plicae circularis

Answer 28

Circular folds, large valvular folds protruding into the lumen. Contain villi

Question 29

Where are the folds in the jejunum

Answer 29

In the mucosa and submucosa

Question 30

Where in the small intestine are large areas of GALT - gut associated lymphoid tissue

Answer 30

Ileum, contains scattered lymphoid tissue called Peyer’s patches.

Question 31

Principle cells of large intestine

Answer 31

Absorptive - For removal of salt and water

Goblet - Secretion of mucus to lubricate the colon

Question 32

Where do the large intestinal tubular glands extend to

Answer 32

Muscularis mucosae

Question 33

Outer smooth longitudinal layer in large intestine is arranged into three muscular strips called?

Answer 33

Teniae coli

Question 34

Difference in structure between colon and appendix

Answer 34

Appendix has less abundant crypts and circular arrangement of lymphoid tissue in submucosa and lamina propriae. This lymphoid tissue declines with age

Question 35

What is the rectoanal junction

Answer 35

Distinct junction between mucosa of rectum and stratified squamous epithelium of anal canal

Question 36

What plexus controls GI tract motility

Answer 36

Myenteric plexus between layers of muscularis externa

Question 37

What helps control secretions in GI epithelium

Answer 37

Submucosal plexus that also controls muscles of muscularis mucosa