Large Intestine Structure and Function Flashcards
Where does the ileum finish and the caecum begin?
The ileocaecal valve
What is the caecum?
The first part of the colon/ large intestine
Why is the caecum described as a blind sac?
Caecum means blind in latin, named because it has no function in humans
What two structures enter the caecum?
The ileocaval valve and vermiform appendix
What regions of the colon are there?
Ascending, transverse, descending and sigmoid
What layers of the muscluaris externa are there in the large intestine?
Circular muscles and longitudinal muscles
Which layer of the muscularis externa is incomplete?
Longitudinal
What muscles lead to puckered appearance of the large intestine?
Contraction of the teniae coli (run entire length of colon)
Describe the histology of the large intestine mucosa?
Mucosa comprised of simple columnar epithelium
Large straight crypts lined with large numbers of goblet cells for lubrication and movement of faeces
Describe the rectum?
Straight muscular tube between end of sigmoid colon and anal pit
What is the difference between the rectal muscular externa and other regions of the canal?
Thick compared to other regions of the canal
What is the anal canal?
2-3cm between the distal rectum and anus
Describe the type of muscles in the anal sphincters
Internal - smooth muscle
External - skeletal muscle
What is the osmotic role of the colon?
Dehydrates chyme and creates faecal pellets
What benefit is three to a long residence time within the large intestine?
Leads to bacterial colonisation which allows fermentation of undigestible carbohydrates to yield short chain fatty acids and vitamin K