[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [General pathology](https://durgical.com/en/general-pathology/) › Gastrointestinal tract

# Gastrointestinal tract

Oesophagus, stomach, small and large bowel, appendix and anus.

55 pages

## Lesion

- [**Achalasia and other motor disorders: loss of the inhibitory neurons** The valve at the lower oesophagus fails to open and the oesophagus stops squeezing, so food and…](https://durgical.com/en/general-pathology/achalasia-and-other-motor-disorders-loss-of-the-inhibitory-neurons/)
- [**Acute appendicitis** When the appendix gets blocked and its pressure rises, bacteria and lack of blood inflame it; if…](https://durgical.com/en/general-pathology/acute-appendicitis/)
- [**Acute gastritis and stress ulcers** Painkillers, alcohol, bile and severe illness can strip the stomach's protective layer, leading…](https://durgical.com/en/general-pathology/acute-gastritis-and-stress-ulcers/)
- [**Angiodysplasia** Tangles of thin, widened blood vessels in the right colon can bleed slowly or heavily in older…](https://durgical.com/en/general-pathology/angiodysplasia/)
- [**Autoimmune atrophic gastritis** The immune system attacks the acid-making cells of the stomach body, so acid and intrinsic…](https://durgical.com/en/general-pathology/autoimmune-atrophic-gastritis/)
- [**Barrett oesophagus** Long-standing reflux turns the lower oesophageal lining into a gut-like lining; this new lining…](https://durgical.com/en/general-pathology/barrett-oesophagus/)
- [**Chemical and infectious oesophagitis** Caustic liquids, stuck tablets, radiation and germs can all inflame the oesophagus; each leaves…](https://durgical.com/en/general-pathology/chemical-and-infectious-oesophagitis/)
- [**Coeliac disease** In genetically prone people, gluten from wheat, rye and barley triggers an immune attack that…](https://durgical.com/en/general-pathology/coeliac-disease/)
- [**Colonic adenomas and serrated lesions** Adenomas are benign gland tumours of the colon that can become cancer; the bigger and more…](https://durgical.com/en/general-pathology/colonic-adenomas-and-serrated-lesions/)
- [**Colorectal adenocarcinoma** Colon cancer grows from polyps over years; right-sided ones bleed silently and cause anaemia…](https://durgical.com/en/general-pathology/colorectal-adenocarcinoma/)
- [**Congenital anomalies of the gut** Some babies are born with a gut that is closed off, narrowed, joined to the airway, outside the…](https://durgical.com/en/general-pathology/congenital-anomalies-of-the-gut/)
- [**Crohn disease** Crohn disease can inflame any part of the gut, in separate patches and through the whole wall…](https://durgical.com/en/general-pathology/crohn-disease/)
- [**Diseases of the peritoneum** The lining of the abdomen can be inflamed by germs or leaking juices, scarred by fibrosis, or…](https://durgical.com/en/general-pathology/diseases-of-the-peritoneum/)
- [**Eosinophilic oesophagitis, and how it differs from reflux** An allergy-type inflammation fills the oesophagus with eosinophils, stiffens it and makes food…](https://durgical.com/en/general-pathology/eosinophilic-oesophagitis-and-how-it-differs-from-reflux/)
- [**Gastric adenocarcinoma: intestinal vs diffuse** Stomach cancer comes in two forms: one forms bulky gland masses after long gastritis; the other…](https://durgical.com/en/general-pathology/gastric-adenocarcinoma-intestinal-vs-diffuse/)
- [**Gastric polyps** Most stomach polyps are harmless overgrowths from gastritis or acid-lowering drugs; gastric…](https://durgical.com/en/general-pathology/gastric-polyps/)
- [**Gastrointestinal lymphoma** The stomach is the commonest place outside the lymph nodes for lymphoma; many arise from…](https://durgical.com/en/general-pathology/gastrointestinal-lymphoma/)
- [**Gastrointestinal neuroendocrine (carcinoid) tumours** Tumours of the gut's hormone cells grow slowly as firm yellow nodules; some release substances…](https://durgical.com/en/general-pathology/gastrointestinal-neuroendocrine-tumours/)
- [**Gastrointestinal stromal tumour (GIST)** The most common sarcoma-type tumour of the gut grows from the gut's pacemaker cells and is…](https://durgical.com/en/general-pathology/gastrointestinal-stromal-tumour/)
- [**Helicobacter pylori gastritis** A spiral bacterium caught in childhood lives in the stomach mucus for life, inflaming it and…](https://durgical.com/en/general-pathology/helicobacter-pylori-gastritis/)
- [**Hirschsprung disease** Nerve cells never reach the end of the colon, so that segment cannot relax; stool backs up and…](https://durgical.com/en/general-pathology/hirschsprung-disease/)
- [**Hypertrophic gastropathies: Ménétrier, Zollinger–Ellison** In these rare diseases the stomach folds become giant because growth signals make the lining…](https://durgical.com/en/general-pathology/hypertrophic-gastropathies-menetrier-zollinger-ellison/)
- [**Intestinal helminths** Worms living in the gut can block it, bleed it, cause anaemia or itching, and some invade the…](https://durgical.com/en/general-pathology/intestinal-helminths/)
- [**Intestinal obstruction** The bowel can be blocked by being trapped in a hernia, tied by scar bands, twisted on itself or…](https://durgical.com/en/general-pathology/intestinal-obstruction/)
- [**Intestinal protozoa: amoebic flask ulcers, Giardia and Cryptosporidium** Single-celled parasites from dirty water either burrow into the colon (amoeba) or cling to the…](https://durgical.com/en/general-pathology/intestinal-protozoa-amoebic-flask-ulcers-giardia-and-cryptosporidium/)
- [**Invasive bacterial enterocolitis** Some bacteria get inside the bowel lining, often through the immune sampling cells, inflaming it…](https://durgical.com/en/general-pathology/invasive-bacterial-enterocolitis/)
- [**Ischaemic bowel disease** When blood flow to the bowel drops, the lining dies first; a sudden block of a major artery can…](https://durgical.com/en/general-pathology/ischaemic-bowel-disease/)
- [**Meckel diverticulum, and true vs false diverticula** A small pouch left over from the yolk-sac duct sits on the ileum; it can bleed, block the bowel…](https://durgical.com/en/general-pathology/meckel-diverticulum-and-true-vs-false-diverticula/)
- [**Non-neoplastic colonic polyps** Many colon polyps are not tumours: some are piled-up normal cells, some come from injury, and…](https://durgical.com/en/general-pathology/non-neoplastic-colonic-polyps/)
- [**Oesophageal adenocarcinoma: from Barrett to invasive cancer** A gland-forming cancer of the lower oesophagus that grows out of Barrett mucosa, linked to…](https://durgical.com/en/general-pathology/oesophageal-adenocarcinoma-from-barrett-to-invasive-cancer/)
- [**Oesophageal lacerations: Mallory–Weiss tear and Boerhaave rupture** Violent retching can split the lining near the stomach (and bleed) or, rarely, burst the whole…](https://durgical.com/en/general-pathology/oesophageal-lacerations-mallory-weiss-tear-and-boerhaave-rupture/)
- [**Oesophageal obstruction: stenosis, webs, rings, diverticula** Scars, thin shelves of lining, rings and pouches can narrow the oesophagus and make food stick](https://durgical.com/en/general-pathology/oesophageal-obstruction-stenosis-webs-rings-diverticula/)
- [**Oesophageal squamous cell carcinoma** A cancer of the flat lining cells of the mid oesophagus, linked to tobacco, alcohol, hot drinks…](https://durgical.com/en/general-pathology/oesophageal-squamous-cell-carcinoma/)
- [**Oesophageal varices: portosystemic collaterals and why they bleed** When blood cannot pass easily through the liver, it detours through veins in the lower…](https://durgical.com/en/general-pathology/oesophageal-varices-portosystemic-collaterals-and-why-they-bleed/)
- [**Other colitis: microscopic, diversion, GVHD, drug** Several kinds of colitis cause diarrhoea with a normal-looking colon; only the biopsy reveals…](https://durgical.com/en/general-pathology/other-colitis-microscopic-diversion-gvhd-drug/)
- [**Other enteropathies** Poor sanitation, faulty immune control, missing enzymes and broken cell machinery can all stop…](https://durgical.com/en/general-pathology/other-enteropathies/)
- [**Peptic ulcer** A peptic ulcer is a deep crater in the stomach or duodenum, usually from H](https://durgical.com/en/general-pathology/peptic-ulcer/)
- [**Pseudomembranous colitis: C. difficile toxins and the volcano lesion** After antibiotics disturb the normal gut bacteria, C](https://durgical.com/en/general-pathology/pseudomembranous-colitis-c-difficile-toxins-and-the-volcano-lesion/)
- [**Pyloric stenosis: infantile hypertrophic and acquired** In some infants the muscle of the stomach outlet grows too thick and blocks it; in adults…](https://durgical.com/en/general-pathology/pyloric-stenosis-infantile-hypertrophic-and-acquired/)
- [**Reflux oesophagitis: what acid does to the squamous lining** When stomach acid repeatedly flows back up, the lining of the lower oesophagus thickens, gets…](https://durgical.com/en/general-pathology/reflux-oesophagitis-what-acid-does-to-the-squamous-lining/)
- [**Sigmoid diverticular disease** High pressure inside the colon pushes its lining out through weak spots in the muscle, forming…](https://durgical.com/en/general-pathology/sigmoid-diverticular-disease/)
- [**The anal canal: haemorrhoids, condyloma and anal carcinoma** Swollen anal veins cause bright red bleeding; HPV can cause warts and, with high-risk types…](https://durgical.com/en/general-pathology/the-anal-canal-haemorrhoids-condyloma-and-anal-carcinoma/)
- [**Tumours of the appendix** The commonest appendix tumour is a small harmless neuroendocrine nodule at its tip; mucus-making…](https://durgical.com/en/general-pathology/tumours-of-the-appendix/)
- [**Typhoid fever: Peyer patch ulcers and typhoid nodules** A Salmonella that only infects humans enters through the small bowel, spreads through the body…](https://durgical.com/en/general-pathology/typhoid-fever-peyer-patch-ulcers-and-typhoid-nodules/)
- [**Ulcerative colitis vs Crohn disease** Ulcerative colitis inflames only the inner lining of the colon, always starting at the rectum…](https://durgical.com/en/general-pathology/ulcerative-colitis-vs-crohn-disease/)
- [**Uncommon gastritis: eosinophilic, lymphocytic and granulomatous** Some gastritis is caused by allergy, by lymphocytes linked to coeliac disease, or by granulomas…](https://durgical.com/en/general-pathology/uncommon-gastritis-eosinophilic-lymphocytic-and-granulomatous/)
- [**Viral gastroenteritis: norovirus, rotavirus, adenovirus and SARS-CoV-2** Viruses kill the absorbing cells at the tips of the villi, causing short bouts of vomiting and…](https://durgical.com/en/general-pathology/viral-gastroenteritis-norovirus-rotavirus-adenovirus-and-sars-cov-2/)
- [**Whipple disease: foamy PAS-positive macrophages in the villi** A rare bacterial infection fills the small-bowel lining with swollen macrophages that block fat…](https://durgical.com/en/general-pathology/whipple-disease-foamy-pas-positive-macrophages-in-the-villi/)

## Process

- [**Colitis-associated neoplasia: dysplasia in long-standing IBD** Years of colitis raise the risk of colon cancer, which often starts in flat abnormal lining that…](https://durgical.com/en/general-pathology/colitis-associated-neoplasia-dysplasia-in-long-standing-ibd/)
- [**Gastric atrophy, intestinal metaplasia and dysplasia** Years of gastritis can thin the stomach lining, turn it gut-like and then produce abnormal cells…](https://durgical.com/en/general-pathology/gastric-atrophy-intestinal-metaplasia-and-dysplasia/)

## Topic

- [**Hereditary colorectal cancer: FAP and Lynch syndrome** Two inherited conditions explain much about colon cancer: one fills the colon with hundreds of…](https://durgical.com/en/general-pathology/hereditary-colorectal-cancer-fap-and-lynch-syndrome/)
- [**Infectious enterocolitis** Germs cause diarrhoea either by making toxins that pump water out, or by invading and inflaming…](https://durgical.com/en/general-pathology/infectious-enterocolitis/)
- [**Malabsorption and diarrhoea** Diarrhoea can come from water being pulled in, pumped out, food not being absorbed, or an…](https://durgical.com/en/general-pathology/malabsorption-and-diarrhoea/)

## Mechanism

- [**Inflammatory bowel disease: pathogenesis** Crohn disease and ulcerative colitis arise when a gut with a weak barrier and inherited risk…](https://durgical.com/en/general-pathology/inflammatory-bowel-disease-pathogenesis/)
- [**Toxin-mediated diarrhoea: cholera and E. coli** Cholera toxin switches intestinal cells into constant salt-and-water pumps; different E](https://durgical.com/en/general-pathology/toxin-mediated-diarrhoea-cholera-and-e-coli/)

## A to Z

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- [C](https://durgical.com/en/general-pathology/a-z/c/)
- [D](https://durgical.com/en/general-pathology/a-z/d/)
- [E](https://durgical.com/en/general-pathology/a-z/e/)
- [F](https://durgical.com/en/general-pathology/a-z/f/)
- [G](https://durgical.com/en/general-pathology/a-z/g/)
- [H](https://durgical.com/en/general-pathology/a-z/h/)
- [I](https://durgical.com/en/general-pathology/a-z/i/)
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- [K](https://durgical.com/en/general-pathology/a-z/k/)
- [L](https://durgical.com/en/general-pathology/a-z/l/)
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- [N](https://durgical.com/en/general-pathology/a-z/n/)
- [O](https://durgical.com/en/general-pathology/a-z/o/)
- [P](https://durgical.com/en/general-pathology/a-z/p/)
- [R](https://durgical.com/en/general-pathology/a-z/r/)
- [S](https://durgical.com/en/general-pathology/a-z/s/)
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- [V](https://durgical.com/en/general-pathology/a-z/v/)
- [W](https://durgical.com/en/general-pathology/a-z/w/)

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Educational content on the mechanisms of disease; not a diagnostic or treatment guide and no substitute for a health professional's advice. No doses are given.

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