Pathology of Colon Flashcards
What is the function of the small bowel?
Absorptive role
What are the functions of the large bowel?
Absorptive and secretory role
How long is the small bowel?
Approximately 6m long
How long is the duodenum?
25cm
What are the 3 parts of the small bowel?
Duodenum
Jejunum
Ileum
What are the different parts of the large bowel?
Caecum
Ascending colon
Transverse colon
Descending colon
Sigmoid colon
Rectum
How long is the rectum?
15cm
What are the different layers of the small bowel wall?
Mucosa
Submucosa
Muscularis propria
Subserosa
What are the layers of the mucosa in small bowel?
Epithelium
Lamina propria
Muscularis mucosa
What cell types are in the mucosa of the small bowel?
Goblet cells
Columnar absorptive cells
Endocrine cells
What is embedded within the mucosa of the small bowel?
Crypts that contain stem, goblet, endocrine and paneth cells
What are the projections from the epithelium of the small bowel?
Villi
What is the muscularis propria also known as?
Muscularis externa
How often is the wall of the small bowel renewed?
Every 4 to 6 days
What is different about the villi of the small bowel and the large bowel?
The large bowel does not contain any villi
What shape is the top of cells in the large bowel?
Flat, no villi
What shape are crypts in the large bowel?
Tubular
What is the difference between crypts in the small intestine and large intestine?
Crypts in the large intestine do not contain paneth cells
What is a consequence of the GI tract having a large surface area?
Large exposure to environment antigens so immune system must balance harmless ingested substances against active defect reactions to potential microbial invaders
What does dysfunction of the intestinal immune system cause?
Chronic disease
Life threatening acute conditions
What is small and large bowel peristalsis mediated by?
Intrinsic (myenteric) plexus and extrinsic (autonomic innervation) neural control
What is the myenteric plexus formed from?
Meissener’s plexus (base of submucosa)
Auerbach plexus (between the inner circular and outer longitudinal layers of the muscularis propria)
Where is the Meissener’s plexus found?
Base of submucosa
Where is the Auerback plexus?
Between the inner circular and outer longitudinal layers of the muscularis propria

