Large intestine Flashcards
What are the 3 parts of the large intestine?
- Caecum a) appendix
2. Colon a) ascending, b) transverse), c) descending, d) sigmoid
Where is the appendix located?
In the caecum (at the junction between the small intestine and the large intestine)
What is the hypothesised function of the appendix?
Immunological function
What is the main function of the large intestine?
Fluid absorption
What is the function of the caecum?
Holds faecal matter
What is 50% of faecal matter?
Bacteria
What is the hepatic flexure?
90 degrees turn at the liver (bend at the liver)
What is the splenic flexure?
90 degrees turn at the spleen (bend at the spleen)
Which features are present in the large intestine that are not found in the small intestine?
- Taenia coli
- Haustrae
- Appendices epiploicae
What are taenia coli?
Bands of muscle tissue running along large intestine
Focal areas where the longitudinal muscle lies (3 separate longitudinal ribbons)
What are haustrae?
Pouches - gives large intestine segmented appearance
What are appendices epiploicae?
Fatty tags on the taenia coli, yellowish in colour
Where is the ileo-caecal junction?
Where the ileum (small intestine) and caecum (large intestine) meet
What is the ileo-caecal valve?
A sphincter at the ileo-caecal junction
A fold of mucosa that allows chyme to pass from S.I. to L.I. but not vice versa
What type of epithelium is in the small intestine?
Simple columnar with goblet cells
What type of epithelium is in the large intestine?
Simple columnar with goblet cells
What are intestinal crypts of Leiberkuhn?
A dip in the epithelium
What is a barium drink?
Barium absorbs X-ray photons so shows up as white on X-ray; allows you to follow fluid moving through G.I. tract on a radiograph
What are the 2 anal sphincters and what type of control are they under?
- Internal and external
- Can control the external but not the internal sphincter
- External sphincter under voluntary control from ~2 years (made of skeletal muscle)
- Internal sphincter made of smooth muscle => involuntary contorl
What is the purpose of goblet cells in the columnar epithelium in the large intestine?
To produce mucus
Mucus protects the epithelium from hard faeces
What are some of the features that differ between the small and large intestine?
- Small intestine has villi, large intestine does not
- Large intestine has incomplete layer of longitudinal muscle (taenia coli)
- Ring-like arrangement of circular muscle (haustrae - forms pouches. Gives large intestine segmented appearance)
Describe the change in epithelium at the recto-anal junction
- Abrupt change in epithelium between simple columnar epithelium to stratified squamous epithelium at the recto-anal junction
- This area is prone to cancer due to sharp demarcation
How much chyme enters the caecum from the ileum?
0.5 - 1.0 L of chyme
What does the colon absorb?
Fluid and electrolytes from the small intestine
