GLM- GI tract Histology

Question 1

Where does the GI tract go from and to?

Answer 1

Lower oesophagus to Upper Anal Canal

Question 2

What are the four layer of GI tract inwards to out?

Answer 2

1) Mucosa
2) Submucosa
3) Muscularis
4) Serosa

Question 3

What are the layers of the mucosa + what do they contain/ functions?

Answer 3

1) Epithelial cells: absorpitive/ secretory functions
2) Lamina Propria: Connective Tissue to support muscosa

Blood vessels

Glandular ducts (region dependent)

3) Muscularis Mucosae: Thin smoth muscle cell layer

Contracts = folds increasing SA digestion + absoprtion

Question 4

What is in the submucosal layer and its functions?

Answer 4

Connective Tissue

Blood vessels

Lymphatic Vessels

Submucosa Plexus (nuerone network part of enteric nervous system)

Question 5

What is in the Muscularis layer?

Answer 5

Most regions it is two layers

(Inner –> Outter)

Circular muscles

Myenteric plexus

Longitudinal Muscle

Question 6

What is in the serosa layer?

Answer 6

Connective tissue covered with simple squamous epithelium

Question 7

What are the functional specialisations of the oesophagus?

Answer 7

Mucosa: Stratified squamous epithelium

Submucosa: Mucus glands for lubrication

Muscularis–> Longitundial: Provide propulsive action of food bolus + liquid to stomach

Voluntary striated in upper oesophagus

Involuntary smooth in distal/lower oesophagus

At Gastroesophageal junction squamous epithelium interdigitates with glandular epithelium

Question 8

What are the functional specialisations of the oesophagus?

Answer 8

Mucosa: Lies in rugae when empty

Non-ciliated columnar epithelium (also lines gastric glands)

Muscularis: x3 layers

Oblique

Circular

Longitudinal

Question 9

What are the functional specialisations of the small intestine?

Answer 9

Mucosa:

• Simple columnar epithelium with microvilli
• Surface Villi -> Increase SA.
• Terminate in lamina propria as crypts of Lieberkuhn
• Contains blind ended lymphatic channel = lacteal

Duodenum:

Submucosa:

• Rounded pale Brunner Glands

Jejunum:

Mucosa:

• Plicae (prominant permanent circular folds) -> Increase SA

Question 10

What are the functional specilisations of the large intestine?

Answer 10

Mucosa: Simple columnar epithelium

lines/ contains absorptive cells + Goblet cells (intestinal glands= long tubes)

Intestinal glands create crypts of Lieberkuhn around them which end in lamina propria