Physiology: large intestine Flashcards
what comprises the large intestine
caecum + appendix, colon, rectum, anal canal + anus
what are the longitudinal smooth muscle in the caecum and colon divided into
3 strands, the taeniae coli
describe the smooth muscle of the rectum and anal canal
it encircles to rectum and anal canal, circular smooth muscle
describe what the ‘haustra’ are in the large intestine
slow moving ‘sac-like’ bulges caused by the activity of taeniae coli and circular smooth muscle in colon
describe how material enters the caecum
entry permitted by gastroileal reflex through the ‘one-way’ ileocaecal valve
what is material permitted entry into the caecum in response to
to gastrin and CCK
what is the role of the ileocaecal valve
maintaining +ve resting pressure
what does the ileocaecal valve relax in response to
distension of duodenum
what does the ileocaecal valve contract in response to
distension of ascending colon
describe the appendix
a blind-ended tube with extensive lymphoid tissue connected to distal caecum via appendicael orifice
how is appendicitis caused
appendicael orifice is obstructed
what are the main absorption functions of the colon
absorb Na, Cl, H2O and short chain FAs
what are the secretory functions of the colon
K, HCO3 and mucous
what are the general functions of the colon
storage of colonic contents and periodic elimination of faeces
