Wk 7: GI Tract

Question 1

What organs are part of the alimentary canal (GIT) (6)

Answer 1

1. Oral cavity
2. Pharynx
3. Oesophagus
4. Stomach
5. Small intestine
6. Large intestine

Question 2

Structure of the tongue (accessory organ)

Answer 2

Skeletal muscle covered with a layer of stratified squamous epithelium

Question 3

What are the projections of the tongue epithelium called & how many types are there

Answer 3

Papillae
4 types

Question 4

What are the 4 types of papillae

Answer 4

1. Filiform (no taste buds)
2. Fungiform
3. Circumvallate
4. Foliate papillae

Question 5

What are the 4 layers that most regions of the alimentary canal contain

Answer 5

1. Mucosa - inner epithelium
2. Submucosa - layer of CT
3. Muscularis externa - layer of SM
4. Serosa - outer layer of CT

Question 6

What are the 3 components of the mucosa layer

Answer 6

1. Epithelium - faces lumen
2. Lamina propria
3. Muscularis mucosae

Question 7

What is the epithelium of the mucosa composed of - epithelial type & cells

Answer 7

• Simple columnar epithelium from stomach to large intestine
• Goblet cells

Question 8

What is the lamina propria of the mucosa composed of - muscle type & others

Answer 8

• Thin layer CT
• Blood
• Lymphatic vessels
• Glands
• MALT

Question 9

What is the muscularis mucosae of the mucosa composed of - muscle type

Answer 9

• 2 thin layers of SM arranged in different directions
• Inner layer is circular
• Outer layer is longitudinal

Question 10

Composition of the submucosa of the alimentary canal

Answer 10

• Dense irregular CT
• Blood, lymphatic vessels & submucosal glands
• Nerve clusters of enteric nervous system (branch of nervous system that governs GIT)

Question 11

What are the nerve clusters of enteric nervous system calles

Answer 11

Submucosal plexus/ Meissner’s plexus

Question 12

Function of submucosal plexus

Answer 12

Each plexus regulates secretion from & blood flow to area of AC

Question 13

Composition of the muscularis externa of the alimentary canal

Answer 13

• Compose of 2 SM layer
• Inner circular & outer longitudinal layer
• Groups of nerves of enteric NS regulate motility

Question 14

What are the nerve clusters of enteric NS found in the muscularis externa called

Answer 14

Myenteric plexus/Auerbach’s plexus

Question 15

Serosa composition - epithelium & muscle

Answer 15

• Simple squamous epithelial tissue
• Loose CT

Question 16

Function of serosa

Answer 16

Support & anchor digestive organs

Question 17

Oesophagus function

Answer 17

To transport bolus from pharynx to stomach

Question 18

Components of the mucosa in the oesophagus

Answer 18

• Stratified squamous non-keratinised epithelium
• Mucous glands

Question 19

Components of the submucosa of the oesophagus

Answer 19

• Mucous glands
• Elastic fibres

Question 20

Components of the muscularis externa of the oesophagus

Answer 20

• 2 layers of muscle (skeletal & smooth)

Question 21

What happens histologically at the esophagus-stomach junction (gastro-oesophageal junction)

Answer 21

Epithelium changes from stratified squamous epithelium in oesophagus to simple columnar epithelium of stomach

Question 22

What are rugae

Answer 22

Folds in the stomach so stomach can expand when food is consumed

Question 23

What is the sphincter entering the stomach & what is the sphincter exiting the stomach

Answer 23

• The sphincter entering the stomach is the gastroesophageal sphincter
• The sphincter exiting the stomach is the pyloric sphincter

Question 24

Whag does the mucosa of the stomach contain (2)

Answer 24

1. gastric pits (columnar cells, goblet cells)
2. gastric glands

Question 25

the 4 main types of cells in the gastric glands

Answer 25

1. Enteroendocrine cells 2. Chief cells 3. Parietal cells 4. Mucous neck cells

Question 26

Functions of the SI

Answer 26

* Secretion * Digestion * Absorption * Propulsion

Question 27

The 3 divisions of the small intestine

Answer 27

1. Duodenum 2. Jujunum 3. Ileum

Question 28

What cells line the SI & produce digestive enzymes

Answer 28

Enterocytes

Question 29

What lymphoid tissue can be found in the SI (small intestine)

Answer 29

Peyer's patches

Question 30

What are the 3 types of folding in the SI & where are they found

Answer 30

1. Circular folds - mucosa & submucosa 2. Villi (mucosa) & Intestinal crypts 3. Microvilli

Question 31

What kind of epithelium are villi & crypts lined with

Answer 31

Simple columnar epithelium

Question 32

Functions of the folds in the SI

Answer 32

* Slow down movement of chyme - increases time for nutrient absorption * Increase surface area for absorption

Question 33

What are the cells in the SI (6)

Answer 33

1. Enterocytes 2. Goblet cells 3. Paneth cells 4. Neuroendocrine cells 5. Stem cells 6. Intraepithelial lymphocytes

Question 34

Function of enterocytes

Answer 34

Intestinal absorptive cells

Question 35

Function of goblet cells

Answer 35

Secrete mucous that protects lining of SI

Question 36

Function of paneth cells

Answer 36

* Located in intestinal crypts * Secrete abundance of antimicrobial peptides that regulate composition of microbiota

Question 37

FUnction of neuroendocrine cells

Answer 37

Neuro immune function

Question 38

Function of stem cells

Answer 38

Restore the cells that need replacing over time

Question 39

What are the 4 regions of the large intestine

Answer 39

1. Caecum 2. Colon 3. Rectum 4. Anus

Question 40

Function of the caecum

Answer 40

Absorption of water & salts

Question 41

Composition of colon

Answer 41

* Simple columnar epithelium * Goblet cells