GI Motility Flashcards
function of ENS
controls intestinal and colonic motility
submucosal plexus
controls epithelial cells in GI tract lining
what does ACh cause
contraction of VIP, NO
what does ATP cause
relaxation
motility in large intestine
faeses stored in haustra which collapses for bulk movements
pacemaker cells control large intestine and aid digestion
process of defaecation
parasympathetic motor neurones in the spinal cord are stimulated -> increasing peristalsis in lower intestine and activating stretch receptors -> distension of rectum and colon -> local peristalsis increased -> internal sphincter relaxes, faeces move into anal canal -> external sphincter stays contracted, receptors accommodate, peristalsis halts and defecatory urge passes
definition of constipation
bowel movements less than three times a week
what causes secondary constipation
endocrine or metabolic diseases, systemic diseases, myopathy, neurological diseases, structural abnormalities, drug related
opioids
inhibit gastric emptying and peristalsis due to suppression of enteric nerve exciteability and transmitter release
this also inhibits ion and fluid secretion
what are enterohinetics
e.g. prucalopride
selective 5-HT4 agonist
promotes motility and mucosal secretion
what are Cl- channel activators
e.g. ubiprostone increases secretion of Cl- and fluid, leading to increased peristalsis
what is osmotic diarrhoea
excessive amounts of insoluble material in the lumen, water is not reabsorbed
what is secretory diarrhoea
abnormal ion transport causes decrease in electrolyte absorption
what is inflammatory diarrhoea
mucosal destruction due to defective absorption of fluid and electrolytes, associated with fluid/blood loss and caused by infection
bacteria induced diarrhoea
ingestion -> intestinal colonisation -> mucosal invasion/ cytotoxic elaboration -> intramucosal multiplication -> diarrhoea
