large intestine Flashcards
what is the colon made up of
ascending
transverse
descending
sigmoid
what does the muscle wall consist of
inner circular
outer longitudinal
what is unique about the outer layer
comes together to form the teniae coli
what does the teniae coli produce
the haustral pattern
what is the mucosa of the colon lined with
epithelial cells and goblet cells
what does the epithelium of the colon contain
crypts
what cells are found in the lamina propria
lymphocytes and macrophages
what is the blood supply to the colon from
superior and inferior mesenteric vessels
what is the colon innervated by
enteric nervous system
what autonomic chains innervate the colon
both
what sphincter is there in the anal canal
internal and external
what are the main roles of the colon
absorption of water and electrolytes
and
propulsion of contents from the caecum to the rectal region
what is absorption stimulated by
short chain fatty acids that are produced in the right colon
what do high amplitude propagative colonic contractions cause
propulsion
what induces peristalsis
serotonin 5-HT
is the rectum normally full or empty
empty
how is stool propelled into the rectum
by propagated colonic contractions
what are defecating sensations associated with
rectal contraction and relaxation of the internal anal sphincter
who is most likely to get constipation
women and the elderly
what is the definition of constipation
two or more of the following for at least 12 weeks:
- infrequent passing of stool <3
- straining >25%
- passage of hard stools
- incomplete evacuation
- sensation of anorectal blockage
what are other symptoms with constipation
- abdominal bloating
- local and perianal pain
causes of constipation
- inadequate fibre intake
- diabetes
- hypercalcaemia
- IBS
drugs: - opiates
- calcium channel blockers
- anti-depressants
psychological: - depression
- anorexia
what investigations are done for constipation
- colonoscopy
- CT
treatment for constipation
- treat underlying
- increase fibre content of diet
- increase fluid intake
- laxatives
how do osmotic laxatives work
increase the colonic inflow of fluid and electrolytes - softens the stools