Inflammatory Bowel Diseases: Crohns & Ulcerative Colitis



hi Andrew wolf here in this video I'm going to talk about the pathophysiology of inflammatory bowel diseases now this includes two related but different diseases one is called Crohn's disease and the other is of course ulcerative colitis now they seem to involve similar pathophysiology in some ways although they involve different tissues and different reactions within the tissues so what do they have in common first well we don't really understand the diseases very well but we do we are sort of zeroing in on two major sort of categories of factors that are causing the disease and that is microbes and the other one is genetic factors and there we don't know specifically which genetic factors are involved but there are twin studies suggesting that there is a strong inherited component to inflammatory bowel disease and how which genes are involved well the genes that seem to be that we seem to have zeroed in on so far are genes that are their polymorphisms or variants relatively common variants of genes call it polymorphism just to remind you of her I think we talked about it in our genetics lecture our variants of genes that occur in 1% of the population or more so relatively common variation so this is different than a rare mutation that would be much much less than 1% so polymorphisms that that cause increased inflammation now microbes we haven't really been able to zero in I would not be surprised if in the next decade or two we similar to how we zeroed in on h pylori for the stomach if we discover a specific microbe or collection of microbes that directly cause either ulcerative colitis or Crohn's disease as of yet we don't know there's been a number of candidates one of the more interesting studies that I read in the last six months or so was a study about how people that are exposed to antibiotics particularly children and teenagers over the next 12 months have a much higher predisposition to developing Crohn's disease or ulcerative colitis now this seems to be because we've disrupted normal flora right and this may allow this may sort of selectively allow the growth of specific microbes that increase inflammation so anyways both Crohn's disease and ulcerative colitis are a disease of inflammation of the mucosa of the bowel that appears to be caused by microbes and polymorphisms of genetic disease now Crohn's disease and inflammatory bowel disease are both inflammatory diseases but Crohn's disease is a disease that can sort of impact anywhere in the GI tract from you know the mouth all the way down through the stomach and the small bowel and the intestines all the way down to the rectum whereas ulcerative colitis is a disease that really always tends to start in the rectum and it can spread up the descending colon and the transverse colon and the descending colon that it sort of stops there sometimes a little bit of inflammation from ulcerative colitis can spread into the distal ileum but that seems to just be spread of sort of inflammatory molecules that wash in sort of back washing from the colon so all sort of colitis hence the title hold sort of colitis really just affects the colon now Crohn's disease on the other hand can really affect everything from the mouth to the anus there are three different possibilities usually there is the most common is Crohn's disease that affects only the small bowel and usually it affects the ileum preferentially then the other possibility is that the ulcerative colitis affects only in the colon and then the third is that it involves both now in rare situations usually it's a disease that's involving both the colon and the small bowel can also involve the esophagus the stomach and even the mouth so that's one difference between the two diseases now another difference between the disease is the way that the ulcers form so with crohn's disease so it crosses these we end up with inflammation that begins on the surface and can spread sort of down the crypts and quickly into deeper layers and it also can begin to ulcerate here let me you can also rate through various layers and it can actually also rate right through all they are the all layers of the bowel even into the mesentery so there are times when you can actually have a perforation of the bowel because of this inflammation okay so Crohn's disease can involve crypts and it can also be transmuted and for this reason because of of the way that it can be transmural it can cause some various serious problems including you can end up with significant scar tissue and fibrosis forming through various layers of the colon and this can lead to strictures it can lead to perforations and these things just don't occur often with ulcerative colitis so with all sort of colitis you end up with severe inflammation but that inflammation politely remains on the surface now the the way that the inflammation occurs in ulcerative colitis it sort of opens it erodes down into small blood vessels and it can lead to significant bleeding again there's always with all sort of colitis that tends to start in the rectum and then it slowly and steadily works its way upwards as the disease progresses so major issues with ulcerative colitis are rectal bleeding and it can actually lead to anemia now this the that's how the diseases are different now let's bring them back together again and talk about some symptoms that they have in common they both commonly present with diarrhea and abdominal pain and this is just due to both of these are due direct results of inflammation weight loss and the weight loss may be in part due to food avoidance because of the pain here didn't finish your writing pain here so that can cause food avoidance which can cause weight loss and the weight loss may also be due to malabsorption because of the inflammation of the gastric mucosa interfering with absorption and then because of the inflammation it frequently causes fevers okay so that basically shows you that the diseases you know share many things in common but I wanted to sort of differentiate them so hopefully you understand how they are similar and how they are different okay so that ends my discussion of inflammatory bowel diseases including Crohn's disease and ulcerative colitis please take a moment to provide feedback and if you have any questions as always you're welcome to ask a question and comments and and I'll do my best to answer it if you want quick and easy access to my other physiology videos I will put some links below thank you very much you

28 comments

  1. What a tragic contradiction and terrible mistake !!! People and especially women are advised to wipe front to back. That means it is realized the danger on t. paper use of UTI, and still everybody keep telling them to use t. paper! How somebody could be sure that the millions of microbes in the remaining feces film, would not later travel to their genitalia?

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  3. Thank you!!!! I believe mine (UC) was because some antibiotics…very painful and annoying illness…

  4. I would have liked more details on signs and symptoms. Crohns has less diarrhea than UC. Also, Crohn's has the "ribbon" sign from the strictures that you discussed. Your video helped me to understand the symptoms more and put it all together. Thank you.

  5. Thanks a lot Anderw Wolf for comprehensive video,you really make me clear but please talk more about investigation and treatment .

  6. READ i.m 51 in good health. Had 5 foot of bowel removed at age 28. Have
    not been to Doc since.I just had 100% block an while at hospital they
    put me on prednisone. IT helped but broke an contaminated my blood,gave
    me a Stroke.

  7. Similar to taking antibiotics leading to flora disruption and greater likelihood of developing Crohn's, is it plausible that a bout of listeriosis could do the same?

  8. Thank you! Great lesson, although I would like to have known the names of the different layers in the bowel.

  9. Thanks for the info! But I do have a question. I'm currently 46, when I was 20 I was first diagnosed with Crohn's, but then within weeks, it was switched to UC. When I was 21, my colon perforated, I was clinically dead from the toxic megacolon, but thankfully was revived. I endured several surgeries, first being a total colectomy with a temp loop ileostomy, then a three step J pouch. For many, many years I was ok, but began developing serious pouchitis around the age of 35. It just worse and worse, and despite having tried almost every drug therapy available, it only grew worse, so I decided that surgery was really my only option left. I opted for a K pouch, so in June 2012, Dr Zane Cohen here in Toronto removed the j pouch, my rectum, and some small bowel, and gave me a new K pouch. Since then, due to several complications, I went from a K pouch, to an end ileostomy, and back to a k pouch. But now, my original symptoms are back, could it be Crohn's after all? Have only 7' of SB left!

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