Structure and function of the large intestine Flashcards
Name the four parts of the large intestine?
Ascending, descending, transverse, sigmoid
Which muscle of the large intestine is complete?
Circular muscle
Which muscle of the large intestine is incomplete?
Longitudinal muscle
What lies on the outside of the colon?
Teniae Coli
What happens when teniae coli contract?
They form haustra
What epithelium lines in the large intestine?
Simple Columnar
What do goblet cells produce?
Mucus
Why is mucus within the large intestine?
To aid with faeces movement
How is faeces formed?
Colon actively transports Na from lumen into blood -> osmotic absorption of water -> dehydration of chyme -> solid faecal pellets
Discuss the importance of intestinal bacteria in the digestive process?
Bacterial fermentation of undigested carbohydrates can occur in colon due to commensal bacteria –> short chain FA’s, Vit K and flatus
Describe the structure of the rectum
Straight muscular tube between end of sigmoid colon and anal canal
Describe the structure of the anal canal?
Tube between distal rectum and anus. Muscularis thicker than rectum to int. anal sphincter. Ext. anal sphincter is made up of skeletal muscle and the epithelium transitions from simple columnar to stratified squamous
Describe the defecation reflex
Contraction of rectum, relaxation of int. sphincter, contraction of external sphincter and increased peristalsis in colon. The ext. sphincter will then relax due to an increase in pressure which will cause faeces to expel themselves
What can cause secretory diarrhoea?
Pathogenic bacteria, protozoa, viruses, toxins, food and stress
Name the two enterotoxigenic bacteria which can cause secretory diarrhoea?
E-Coli, Vibrio Cholerae
