GI Tract Microanatomy

Question 1

What is the inner lining of the GI tract called?

Answer 1

Mucosa

Question 2

What is the support layer of the GI tract called?

Answer 2

Submucosa

Question 3

What is the muscle layer of the GI tract called?

Answer 3

Muscularis externa/propria

Question 4

What is the outer wrapping of the GI tract called?

Answer 4

Adventitia/serosa

Question 5

Name the 4 layers of the GI tract from lumen outwards

Answer 5

Mucosa
Submucosa
Muscularis externa/propria
Adventitia/serosa

Question 6

What 4 things make up the mucosa?

Answer 6

Epithelium, basement membrane, lamina propria, muscularis mucosa

Question 7

What is the role of the lamina propria?

Answer 7

Supports the epithelium structurally and nutritionally

Question 8

What type of epithelium lines the oral cavity, pharynx, oesophagus and anal canal?

Answer 8

Protective

Stratified squamous, non keratinising

Question 9

What type of epithelium lines the stomach?

Answer 9

Secretory

Simple or branched tubular glands

Question 10

Describe some features of the epithelium of the small intestine

Answer 10

Absorptive
Villi and crypts lines by columnar cells called enterocytes
Goblet cells producing mucus

Question 11

Describe some features of the epithelium of the large intestine

Answer 11

Absorptive and protective
High number of goblet cells for lubrication
Presence of enterocytes

Question 12

What is the submucosa made up of?

Answer 12

Connective tissue, blood vessels, lymphatics and nerves
Some glands
Submucosal (Meissner’s) plexus

Question 13

What does the submucosal plexus innervate?

Answer 13

Glands

Muscularis mucosa

Question 14

What is the muscularis externa/propria made up of?

Answer 14

Smooth muscle

Myenteric (Auerbach’s) plexus

Question 15

What process does the myenteric plexus modulate?

Answer 15

Peristalsis

Question 16

What is adventitia?

Answer 16

The outer wall of the gut tube, made up of a thin layer of connective tissue

Question 17

What is serosa and where is it associated with?

Answer 17

A serous membrane covering the GI tract

Peritoneum

Question 18

What kind of epithelium makes up a serous membrane?

Answer 18

Squamous epithelial cells secreting a small amount of fluid

Question 19

What is a sphincter?

Answer 19

Thickening of the smooth muscle in the GI tract

Question 20

Name the 4 sphincters of the GI tract

Answer 20

Oesophageogastric
Pyloric
Ileocaecal
Internal anal

Question 21

Gut associated lymphoid tissue (GALT) is located in the …

Answer 21

Lamina propria

Question 22

What are Peyer’s patches and where in the GI tract are they located?

Answer 22

Collections of lymphoid follicles

Ileum

Question 23

The oral cavity and pharynx only have which 2 of the 4 layers?

Answer 23

Mucosa and submucosa

Question 24

Which part of the mucosa is not present in the oral cavity and pharynx ?

Answer 24

Muscularis mucosa

Question 25

Name the 3 paired salivary glands

Answer 25

Parotid Submandibular Sublingual

Question 26

All 3 paired salivary glands consist of ...

Answer 26

Lobules of acini and ducts, divided by connective tissue septa

Question 27

The tongue is a bulk of interlaced bundles of ... covered by ...

Answer 27

Skeletal muscle | Oral epithelium

Question 28

Describe the pattern of the muscularis layer of the oesophagus

Answer 28

Skeletal in the first third Smooth in the last third Mixed in the middle third

Question 29

Describe the change in epithelium at the gastro-oesophageal junction

Answer 29

Changes from squamous to columnar epithelium (glandular)

Question 30

What type of epithelium is the luminar surface of the stomach made up of

Answer 30

Columnar epithelium mucous cells

Question 31

The oblique layer is an additional muscle layer lining which organ

Answer 31

Stomach

Question 32

What 4 types of cells line the gastric pits and glands

Answer 32

Mucous cells Parietal cells Chief cells Enteroendocrine cells

Question 33

What do the mucous cells of the gastric pits and glands produce?

Answer 33

Mucous and bicarbonate

Question 34

What do the parietal cells of the gastric pits and glands produce?

Answer 34

HCl and intrinsic factor

Question 35

What do the chief cells of the gastric pits and glands produce?

Answer 35

Enzymes such as pepsinogen

Question 36

What do the enteroendocrine cells of the gastric pits and glands produce?

Answer 36

Hormones such as gastrin

Question 37

What epithelium lines the villi of the small intestine?

Answer 37

Simple columnar epithelium

Question 38

What is the function of enterocytes in the SI epithelium?

Answer 38

Absorption | Brush border enzymes aid digestion

Question 39

What is the function of goblet cells in the SI epithelium?

Answer 39

Secrete mucus

Question 40

What is the function of paneth cells in the SI epithelium?

Answer 40

Release defensins to protect against infection

Question 41

What is the function of enteroendocrine cells in the SI epithelium?

Answer 41

Secrete locally acting hormones regulating secretion and motility

Question 42

What is the function of stem cells in the SI epithelium?

Answer 42

Divide and replace the different cells contained in the SI epithelium

Question 43

The anal canal is a muscular canal controlled by 2 ...

Answer 43

Sphincters | Internal and external

Question 44

Whats the difference between the internal and external anal sphincter

Answer 44

Internal- Smooth muscle, involuntary control | External- Skeletal muscle, voluntary control

Question 45

Change in epithelium from the rectum to anus

Answer 45

Columnar to stratified squamous

Question 46

... are responsible for the lubrication of passage of faeces

Answer 46

Anal glands

Question 47

Define exocrine

Answer 47

Containing glands which secrete their products through ducts opening on to an epithelium rather than directly into the blood.

Question 48

Define endocrine

Answer 48

Containing glands which secrete hormones or other products directly into the blood.

Question 49

What are acini

Answer 49

Clusters of secretory cells (columnar) that surround ducts

Question 50

What is secreted by the duct epithelial cells in the pancreas

Answer 50

Bicarbonate ions and water (together make pancreatic juice)