Digestive System: Appendix, Colon, Rectum, Anal canal Flashcards
What is another name for the appendix?
Vermiform appendix
What is the appendix?
A blind pouch on the right extending from the cecum
What is the surface epithelium of the appendix?
Simple columnar with surface absorptive cells, goblets, regenerative cells, and DNES cells
Does the appendix have a lamina propria?
Yes
Does the appendix have a muscularis mucosae?
Yes but it’s poorly developed
Does the appendix have crypts? Villi? Paneth cells?
Yes, it has short crypts
NO villi
No to infrequent Paneth cells
How is the appendix submucosa?
Thick layer with large blood vessels
What are notable structures within the appendix submucosa?
Numerous lymph nodules
Does the appendix have a muscularis externa?
Yes, it is thin with a normal pattern (inner circular, outer longitudinal)
Does the appendix have a serosa?
Yes
What are the functions of the appendix?
Humoral immunity
Reservoir for good bacteria
What structures make up the large intestine?
Cecum, colon, rectum, anus
What are the portions of the colon?
Ascending, transverse, descending, sigmoid portions
What structures are histologically similar to the colon?
Cecum
Rectum
What are the general functions of the colon?
- Absorption of water (primary function)
- Compaction, lubrication, elimination of feces
- Production of some vitamins as bacterial by products
What vitamins are produced by the colon?
Riboflavin
Thiamin
Vitamin K
B12
What is the surface epithelium of the colon?
Simple columnar with many goblets, surface absorptive cells (colonocytes), some regenerative cells, very few DNES cells
What is another name for the surface absorptive cells of the colon?
Colonocytes
How is the lamina propria of the colon?
Typical and has crypts (intestinal glands)
How is the muscularis mucosae of the colon?
Typical
What is lacking in the mucosa of the colon?
Villi
Paneth cells
How is the submucosa of the colon?
Typical
How’s the pattern of the colon’s muscularis externa?
Not normal
What are teniae (taenia) coli?
Discontinuous bands of outer longitudinal muscle
What results from constant tonus of teniae coli?
Sacculations called Haustra
Adventitia in the colon make up…?
Ascending and descending colon
Serosa in the colon make up…?
Transverse and sigmoid colon
What is the general function of the rectum?
Store fecal material
What surface epithelium makes up the rectum?
Simple columnar with crypts and goblet cells
What are the notable features of the rectum?
Significant luminal wall folds exists called transverse rectal folds
No teniae coli in ME which makes longitudinal muscle more complete
Lumina wall includes adventitia (vertical rectal folds)
How long is the anal canal?
4 cm
What structure is the anal canal similar to?
Colon
What structure is the rectum similar to?
Colon
What surface epithelium makes up the anal canal?
Transitions to stratified squamous
What glands are in the anal canal?
Anal glands
Circumanal (apocrine) glands
Where are the anal glands and what’s their function?
They extend into the submucosa and produce mucus to lubricate the lumen
Where are the circumanal (apocrine) glands?
In skin surrounding anus
What do the mucosa and submucosa of the anal canal contain?
Longitudinal folds creating anal columns
What disappears into the anal canal?
Muscularis mucosae
What sphincters are within the anal canal?
Internal anal sphincter
External anal sphincter
What makes up the internal anal sphincter?
Thick circular layer of smooth muscle within the muscularis externa
What makes up the external anal sphincter?
Striated (voluntary) muscle from the pelvic floor
What covers the luminal wall in the anal canal?
Adventitia
