Epithelia Of The Gut

Question 1

Describe the epithelia of the gut

Answer 1

• Stratified squamous at oesophagus + distal anus
• Simple columnar in between

Question 2

Describe the epithelia of the stomach

Answer 2

• simple columnar > surface mucous cells
• secrete mucus/HCO3 > forms barrier to stomach acid
• line gastric mucosa + form gastric pits which connect to gastric glands in lamina propria - surface > neck mucous cells

Question 3

Where is simple squamous epithelia found in the gut?
What properties does it have?

Answer 3

• Oesophagus + distal anus
• resists abrasion
• non-keratinised > secretes mucus

Question 4

Compare surface mucous cells and neck mucous cells

Answer 4

Neck mucous cells are smaller, irregular + have smaller vacuoles of mucin - found at base of gastric pits

Question 5

Describe the epithelia of the small intestine

Answer 5

• many folds of surface to increase SA >villi + microvilli to increase further
• mainly enterocytes on surface on small intestine
• some goblet cells > produce mucus

Question 6

What three things does mucus protect epithelia from and how?

Answer 6

• friction - acts as a lubricant
• chemical damage (acidic environment) - alkaline mucous
• bacterial inflammation - forms a physical barrier

Question 7

Describe the crypts in the GI tract

Answer 7

• stem cells > replace epithelia every 2-4 days
• paneth cells > at base of crypt > secrete antibacterial proteins which protect the stem cells
• enteroendocrine cells > secrete hormones that control gut function e.g. gastrin, cholecystokinin, secretin

Question 8

Describe the epithelia in the colon

Answer 8

• tall columnar epithelia (coloncytes) - contain lateral intercellular spaces for water movement
• goblet cells > secrete mucus > supports micro biome
• no villi

Question 9

Role of Brunner’s glands

Answer 9

Secrete an alkaline fluid containing mucin which protects the mucosa from acidic chyme