Lower GIT Flashcards
what is the function of the small intestine
absorption of nutrients and mixing of chyme with secretions from the liver and pancreas such as bile or bicarbonate for neutralisation of stomach acid
what are the two mechanisms of the small intestine and how do they work
spontaneous contractions of the smooth muscle that increase post prandially, contractions are greater in the duodenum
migrating motor complex regulating contraction of smooth muscle distally from the duodenum
what is segmentation in the small intestine
mixing of chyme with secretions via rhythmic divisions and subdivisions within the si
how does propulsion occur in the small intestine
sequential contraction of adjacent circular smooth muscle following by proximal relaxation
how long is one propulsion
about 10cm
what is a full length contraction of the small intestine called
peristaltic brushes
what three plexi control mediate motility
myenteric, submyenteric, intrinsic
what do the plexi in the SI do
enables segmentation and short peristaltic waves to occur
what peptides can modulate motility and rhythm of peristaltic waves in he si
VIP, substance p and opioids
what effect does enteric glycogen have on motility
inhibits it so that there can be more absorption
describe the gastrio illio reflex
distension of the stomach causes relaxation of the ileum (feedforward) but over distension of the ileum causes the stomach to reduce gastric emptying into the duodenum (feedback)
what is parioltyic ilues
ability for external organs outside the GIT to modulate motility
what are the 4 types of laxatives for constipation
secretary - increases intestinal secretions to act as lube
osmotic such as epsom salts which encourage osmosis of water from ecf to lumen
emollients such as parafen - lubricating
bulk forming agents such as bran high in fibre
what is the connection between the small intestine called
ileo-caecal sphincter
what is the outer layer of the large intestine called
tanie coli
describe the muscles of the large intestine e
mainly circular muscle that gets thicker towards the end of the colon towards the rectum
what is the large intestine divided into
haustra which controlled contractions of the circular muscle
how does propulsion occur in the large intestine
sequential contractions of haustra in peristaltic waves
what is the speed of movement of chyme in the colon before and after food
before food it is about 5cm per hour
after eating it is about 10 cm per hour
which part of the colon contacts
ascending an transverse contract but descending and sigmoid causes distention
what is the defication reflex
distention of the rectum causing relaxation of the anal sphincter
what are the three types of contraction in the large intestine
mass movements - prolonged peristaltic
anti peristaltic contractions to allow more water and electrolytes to be absorbed halting motility
segmentation contractions shopping and mixing which cause formation of the haustra
what are the symptoms of IBS
nausea stomach cramps diarrhoea constipation frequent defication
how can you relieve symptoms of IBS
bulk forming laxatives
antispasmodic - reduce cramping - peppermint oil and increase motility
anti motility - lowpermide - reduce frequent defections
TCA’s and SSRI to reduce cramps