Lecture 23: The large intestine and liver Flashcards
What is the main role of the large intestine?
- Absorption of water (some sodium as well)
- Storage of feces until defecation
What does the large intestine consist of?
- Consists of cecum, colon, and rectum
What can the colon be divided into (terms)?
Colon divided into:
* Ascending
* Transverse
* Descending
* Sigmoid
What are the locations of the respective parts of the large intestine?
- Ascending and descending colon are retroperitoneal
- Transverse and sigmoid colon are intraperitoneal
What enables imaging of the large intestine?
- A Barium enema enables imaging to assess function
What is the cecum?
- Blind-ended pouch
- Location of appendix
- Ileocecal valve regulates the passage of material into the
large intestine
What is the appendix and what is its function?
- known as the Vermiform appendix
- is a Reserve of large intestine bacteria
- Attached to cecum
- Can become inflamed = appendicitis
Why does the large intestinal wall need to be modified?
Needs to be modified to:
* Store feces
* Expel feces during defecation
* Be lubricated
* Allow absorption of water
What are some features of the large intestinal wall?
Teniae Coli:
* Bands of longitudinal muscle
Haustra:
* Series of pouches
Omental appendices:
* Sacs of fat
Semilunar folds (between haustra)
- increase SA and help stores things longer
Describe the muscularis of the large intestine:
- Inner circular layer
- Outer longitudinal layer forms three thick bands (Teniae coli)
- Allows for stronger contraction
Describe the large intestine mucosa:
- Lack of villi
- Mucosa invaginates to form intestinal glands
- Simple columnar epithelium
What cells can be found in the large intestinal mucosa?
- Absorptive cells for water and salt
- Goblet cells produce mucus for protection and lubrication
Where is the rectum and what does it do?
- The rectum is the last part of the large intestine
- Stores feces
What connects the rectum to the anus?
anal canal
What marks the boundary where epithelium changes in the anal canal and anus and what types of epithelium are there?
Anal columns mark boundary where epithelium changes
* Before: simple columnar
* After (anus): stratified squamous