Lower GI Disorders Flashcards
Which artery supplies the proximal colon?
Superior mesenteric artery
Which artery supplies the distal colon?
Inferior mesenteric artery
Which venous vessels drain the colon?
Inferior and superior mesenteric veins draining into the portal vein
What structures reside within the submucosal space?
Submucosal glands and Meissner’s plexus
Which molecule is secreted by the submucosal glands, lubricating the mucosal surface?
Mucin
Between which two layers does the myenteric plexus reside?
Intermediate between the circular and longitudinal muscles within the muscularis layer
Where are the myenteric plexus ganglia located in relation to the taenia coli?
Concentrated deep to the taenia coli
Which nerve provides the parasympathetic supply to the ascending and proximal transverse colon?
Vagus nerve
Which nerves provides parasympathetic supply to the distal transverse and descending colon?
Pelvic nerves
What is the sympathetic supply of the colon?
Pre-ganglionic fibres arise from the thoracolumbar spinal cord
Which nerve controls the external anal sphincter?
Pudenal nerves
What are the nerve roots of the pudenal nerves?
S1-S3
What is Hirschprung;s disease?
Characterised by a congenial absence of myenteric and Meissner’s ganglion.
• Peristalsis is impaired due to unstimulated muscular contractions within the muscularis layer.
• Obstruction Constipation.
• There is an absence of propulsive peristalsis and mass contraction in the aganglionic segment.
What are the inflammatory causes of lower GI tract disorders?
IBD and microscopic colitis
What are the infective causes of lower GI tract disorders?
C. difficile
E. coli
What are the structural causes of lower GI tract disorders?
Diverticular disease
Haemorrhoids
Fissures
What are the functional causes of lower GI tract diosrders?
IBS
What are the neoplastic causes of lower GI tract disorders?
Colonic polyps
Colon cancer
What are the two causes of IBD?
Ulcerative colitis
Crohn’s disease
What is ulcerative colitis?
Inflammatory disorder characterised by diffuse inflammation of colonic superficial mucosa.
No granulomas
Extends continuously and proximally from the rectum
Which GI organ is always concerned with ulcerative colitis?
Rectum
What is proctitis?
Inflammation of the rectum
What is pancolitis?
Inflammation of the entire colon
What term describes ulcerative colitis of the rectum and sigmoid colon?
Proctosigmoiditis
What is distal colitis?
Diffuse continuous inflammation from the rectum to the ascending colon
What are the symptoms concerned with ulcerative colitis?
Patients present with severe and frequent rectal bleeding, diarrhoea, and blood in stool (detected on digital rectal examination)
What is Crohn’s disease?
Characterised by transmural inflammation of the gastrointestinal tract, predominantly in the terminal ileum and perianal locations
Skip lesions
inflammation can penetrate through the serosa, giving rise to perforations and fistulae
Inflammatory infiltrate initially begins around intestinal crypts, developing into ulcerations of the superficial mucosa.
• Inflammation progresses to involve non-caseating granulomas (all layers of the intestinal wall and the mesentery are affected).
• Granulomatous inflammation is characteristic of CD.
• Strictures are narrowing of the bowel due to inflammation.
N.B: Involvement of the terminal ileum will disrupt bile acid absorption Steatorrhea and fat-soluble vitamin deficiency.
Which areas of the GI tract does Crohn’s disease predominantly affect?
Terminal ileum and perianal locations
What are the characteristic features of Crohn’s disease?
Skip lesions Fistulae Transmural inflammation Strictures Non-caseating granulomas