Large Intestine Flashcards
What are the three parts of the large intestine?
caecum, colon, rectum
Where is the appendix?
near the caecum
What is the appendix?
small tube that attaches to the caecum, no function and non-essential
What parts of the large intestine are intraperitoneal?
caecum
sigmoid
transverse
What structure is between the ileum and the caecum and what is it’s function?
ileocaecal valve. prevents reflux of large bowel contents into the ileum during peristalsis and is thought to function passively.
What are the four parts of the colon?
ascending, transverse, descending, sigmoid
What is the 90 degree point in the colon that is closest to the liver called?
hepatic flexure (right colic flexure)
What is the 90 degree point in the colon furthest from the liver called?
splenic flexure (left colic flexure)
Is there villi in the large intestine?
no
What are the 3 bands of smooth muscles running longitudinally outside the ascending, transverse, and descending colon?
taenia coli
What are circumferential contractions of the inner muscular layer of the colon called?
haustrations
What is appendices epiploicae?
Pouches of peritoneum filled with fat mainly on the transverse and sigmoid colon, though not the rectum
What is haustra?
Contraction of the teniae coli exerts pressure on the wall and creates a series of pouches, called haustra
What does the rectum temporarily store?
faeces
Where does the rectum terminate?
anal canal
What are the differences between the colon and rectum?
rectum has an absence of taenia coli, haustra, and omental appendices.
Where in the rectum does the movement of faeces occur?
the rectal valves
What are the internal hemorrhoidal plexus?
collection of veins in rectum. these veins communicate directly between the portal and systemic venous system. Any drugs given rectally can act much quicker by bypassing metabolism by passing through the gut.
What is used to diagnose large intestine and rectum issues and how does it work?
barium enemas is used, filling the large intestine with diluted barium liquid while X-ray images are being taken.
What is the ileocaecal valve and what does it allow?
fold of mucosa that allows chyme to pass from small intestine to large intestine but not vice versa
What is the layers and glands of the large intestine?
simple columnar epithelium with goblet cells with crypts of liberkuhn (glands of intestinal juice) and mucous glands. lamina propria, muscularis mucosae,
submucosa (meissner’s plexus)
muscularis propria
muscularis externa (auerbach’s plexus)
serosa
What are the difference between the lining of the small intestine and the large intestine?
large intestine has no villi
has taenia coli
has haustra
has omental appendices
What are crypts covered by and what do they secrete?
covered by epithelium of 2 types – goblet cells which secrete mucous and enterocytes that secrete water and electrolytes.
Describe the internal anal sphincter
made up of smooth muscle
contractions are involuntary
Describe the external anal sphincter
made up of skeletal muscle which is under voluntary control
What does the colon absorb?
fluid and electrolytes from chyme coming from small intestine.
What condition does failure of the colon to absorb called?
diarrhoea
What is the large intestine’s resident microbial population called?
intestinal bacterial flora
What are the roles of bacterial flora?
ferment dietary fibre (cellulose) and lipid
produce gases (flatus)
synthesise vitamins (B complex, K)
What does vitamin B complex do?
8 different types of B vitamins, direct impact on energy levels, brain function and cell metabolism. Vitamin B complex helps prevent infections and good for cell health, growth of red blood cells and nerve function.
What does vitamin K do?
fat soluble, and is needed for blood clotting, and helping wounds to heal.
Where does most large intestine motley occur?
caecum and ascending colon
What are the two types of movement in the large intestine?
peristalsis and mass movement
Describe peristalsis in the large intestine
short range waves in the transverse and descending colon
propels faecal matter towards the rectum
Describe mass movements in the large intestine
infrequent contractions
usually after meals in gastro-colic reflex
moves chyme/faeces from caecum to rectum
rectal distension associated with desire to defaecate
What is defection?
the involuntary reflex ejection of faecal matter from rectum via anal canal
What muscle is the rectum and internal anal sphincter?
smooth
What nervous system controls the rectum and internal anal sphincter?
ANS
What type of muscle is the external anal sphincter?
skeletal striated muscle that is voluntary
What is ileostomy?
when the proximal end of the ileum is brought out through the abdominal wall and the faecal matter is collected in a bag
What is colostomy?
when the proximal end of the colon is brought out through the abdominal wall and the faecal matter is collected in a bag
What is a stoma?
the opening made in an ileostomy/ colostomy
When would a ileostomy/colostomy be needed?
cancer, ibd
What is diarrhoea characterised by?
excessively watery stool
What is diarrhoea mostly caused by?
GIT infections
What does diarrhoea indicate?
failure of fluid absorption
What are the results of diarrhoea?
dehydration, electrolyte imbalance
What is constipation characterised by?
hard stool
What is constipation due to?
increased absorption
What drugs may cause constipation?
opiates
What is constipation associated with?
gastrointestinal spasm
What artery supplies the large intestine?
superior mesenteric artery and inferior mesenteric artery
What veins drain the large intestine?
inferior and superior mesenteric join to the hepatic portal vein
