Large Intestine Flashcards
(30 cards)
how long is the large intestine
1.7m
what is the large intestine comprised of
caecum, appendix, colons, rectum, anal canal and anus
what is the taeniae coil
longitudinal smooth muscle layer in caecum and colon that is divided into 3 strands
where is smooth muscle thickened
internal anal sphincter
what Is the internal anal sphincter surrounded by
skeletal muscle of the external anal sphincter
what is the haustra
sac like bulges due to activity of teaniae coli and circular muscle layers
what permits entry of material from terminal ileum to caecum
gastroileal reflex
when does the one way ileocacecal valve relax
reponse to distention of the duodenum
when does the one way ileocacecal valve contract
response to distention of the ascending colon
what type of tissue does the appendix contain lots of
lymphoid
what can happen when the appendiceal orifice is obstructed by a faecalith
appendicitis
what does the colon absorb
Na+, Cl-, H2O, short chain fatty acids
what happens to carbohydrate not absorbed by the small intestine
it is fermented by colonic flora to short chain fatty acids
what does the colon secrete
K+, HCO3-, mucus
what increases surface area of the colon
colonic folds
crypts
microvilli
what are coloncytes
surface epithelial cells of colon
what do coloncytes mediate
electrolytes absorption by osmosis drives absorption of water.
which cells mediate ion secretion
crypt cells
what does mucus contain
glycosaminoglycans hydrated to form a slippy surface gel and secrete trefoil proteins involved in host defence
what do glycosaminoglycans form and secrete
hydrated to form a slippy surface gel and secrete trefoil proteins involved in host defence
what hormone enhances sodium ion absorption and potassium ion secretion
aldosterone
what is no propulsive segmentation
haustration
difference between haustartion and segmentation
haustartion has a much lower frequency contributing to a long transit time
where does mass movement occur
ascending and transverse colon
