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Medicine Notes Gastrointestinal (GI) System Notes

Crohn's Disease Notes

Updated Crohn's Disease Notes

Gastrointestinal (GI) System Notes

Gastrointestinal (GI) System

Approximately 57 pages

These notes helped me achieve a mark of 73% in my GI exam, which is the equivalent of a 1st. The notes are based on a series of lectures on the subject. They are very clearly laid out and easy to follow. They cut out unnecessary information on the topic, making the notes very concise, and fast to get through. Anyone studying medicine, or any other subject requiring knowledge of the GI tract (e.g. physiology or anatomy), would benefit greatly from these notes. There are lecture in the series on th...

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The following is a more accessible plain text extract of the PDF sample above, taken from our Gastrointestinal (GI) System Notes. Due to the challenges of extracting text from PDFs, it will have odd formatting:

Lecture 24

Crohn’s Disease

  • What is Crohn’s disease?

    • Chronic inflammatory disease, effects anywhere from mouth-anus (UC is only colon)

    • Characterised by patchy inflammation with ulceration (unlike UC, which is confluent)

    • Symptoms determined by site of disease and severity of inflammation & the complications of inflammation

  • Symptoms

    • Pain: Constant or in waves (inflammatory stricture of bowel)

    • Diarrhoea: Loose/severe, may be bloody

    • Weight loss: Due to disease, poor absorption & loss of appetite

    • Fatigue: Partly anaemia, but hard to treat

  • Who gets it?

    • Getting more common

    • Bimodal=young adults & middle aged

    • 1 in 500

    • Can run in families; Developed nations

    • More common in smokers (opposite of UC)

  • Site of disease

    • Enterocolitis (small & large bowel) 50%

    • Enteritis (small bowel) 29%

    • Colitis (large bowel) 19%

    • Other sites (e.g. cutaneous) 2%

  • What causes Crohn’s disease?

    • BACTERIA (abnormal)

      • Bacterial flora change (is it because of CD or does it cause CD?)

      • In general, reduced diversity of Firmicutes & Bacterioides

      • Increased mucosa-associated E. coli in Crohn’s disease

        • Adherent Invasive E. Coli (AIEC)- able to penetrate gut wall, difficult to kill once there and sit in macs causing inflammation

      • Abnormalities

        • Loss of some Firmicutes & Bacterioides

        • Role of (AIEC)

        • BUT- Crohn’s disease not transmittable, & what about familial risk?

    • Mucus (defective)

      • Too much mucin (opposite of UC)

      • Mutation of MUC 19 gene in CD

    • Bowel wall (leaky)

      • Abnormal permeability

        • In CD patients and relatives

        • Tight junction defects

        • May be secondary to inflammation BUT

          • MYO9B gene mutation associated with UC

          • Gene in CD disputed

      • Abnormal defence

        • Defective mucus layer and epithelial barrier MAY permit invasion of gut wall by bacteria

    • Recognition (abnormal); Inflammation (dysregulated); Enhanced recruitment of inflammatory cells

      • Macrophages

        • Bug comes along and is engulfed

        • Become phagocytised

        • Lots of white cells come along= inflammation and damage

  • Why do some people’s macs not work? RECOGNITION ABNORMALITIES

    • Two types

      • NOD2

        • 1st gene susceptibility locus on genes for Crohn’s

        • NOD2 involved in recognition of foreign antibodies

          • Mutation= can’t deal with antigens etc.

        • Significant increased risk of CD in those homozygous for NOD2 mutation

      • Autophagy

        • Another way cell can deal with bacteria

        • If...

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