Large bowel Flashcards
What is the primary function of the large bowel?
To reabsorb nutrients, electrolytes, and water; synthesises specific vitamins in addition to formant eliminate faeces
What are the 5 main features of the large bowel?
Caecum Colon Appendix Rectum Anal canal
What is the initial region of the large bowel?
Caecum
Which valve connects the ileum and caecum?
Ileocecal valve
What is the vermiform appendix?
Tube that attaches to the caecum, contains lymphoid tissue considered vestigial
What are the three main colonic regions?
Ascending colon
Transverse colon
Descending colon
Where is the ascending colon in relation to the abdomen?
Right abdomen
Which flexure bends the ascending colon into the transverse colon?
Hepatic flexure
Which flexure bends the transverse colon into the descending colon?
Splenic flexure
Which structure attaches the transverse colon to the stomach?
The lesser omentum
What is the relation between the descending colon and the abdomen?
Descends down the left side of the posterior abdominal wall
Where does the descending colon end?
Runs inferiorly into the pelvis, becoming the W-shaped sigmoid colon -> Rectum
Which arteries happy the proximal transverse colon?
Middle colic artery - branch of the superior mesenteric artery
Which artery supplies the distal third of the transverse colon?
Inferior mesenteric artery
What does the arterial to the proximal and distal transverse colon supply reflect?
Reflects the embryological divisions between the midgut and hind-gut
Which regions of the transverse colonies sensitive to ischaemia?
Regions between the proximal and distal transverse colon (middle)
Is not supplied significantly by the inferior and superior mesenteric artery
What are Taenia coli?
These comprise of three bands of muscle that comprise the longitudinal muscle of the muscular layer of large intestine
What punches are formed upon the tonic contractions of the Tania coli?
Bunches the colon into succession of ovoid pouches referred as haustra
What is the function of Taenia coli?
Large intestinal motility through muscular contractions, shorter than small intestine
What are attached to Tania coli which provideprotecxting functions against intra-abdominal infections?
Fat filled sacs of visceral peritoneum called epileptic appendages
What are the lymphoid tissues within the walls of the distal small intestine called?
Peyer’s patches
What are the large intestine lymphoid tissues?
Solitary nodules
Which parts of the large bowel is absent of taenia coli?
Rectum and anal canal, have established layers of muscularis for defecation
Which epithelial lining lines the anal canal?
Stratified squamous epithelial mucosa of the anal canal connects to the skin on the external anus
What are anal columns?
Mucous membrane organised into longitudinal folds, encapsulating network of arteries and veins. Two superficial venous plexuses are located in the anal canal
What are the depressions between anal columns that secretes mucous that facilitates defecation?
Anal sinuses
Where is the majority of electrolytes and water absorbed within the large bowel?
Proximal colon
How are chloride and sodium ions reabsorbed iii the colon?
Exchange mechanism and ion channels, change sin osmolarity result in water absorption by osmosis.
How much water is reabsorbed by the large intestine?
4.5L
What folds are located within the submucosal layer of the rectum?
Transverse rectal folds, and the absence of taenia coli in its muscularis externally
Where does the anal canal open up into?
Opens into the anus