GI Tract Pathology 

Pre-Knlowge of GI Tract

• the diaphragm separates the esoágues from the stomach
• parietal cells produce HCl and KCl (gastric acid) and excrete it in gastric glands
• What happens when someone vomits for days?
  • hypochloremic (hyper chloride) in blood
  • lower pH in the stomach
• PAS staining
  • Staines the lining of the mucus → polysaccharides
• Bolus moves passively and actively through the esophagus( peristaltic movement)
• Different squinters in GI tract
• 

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Functions and Characteristics of the GI tract

• %%Small intestines%% → absorption of carbohydrates, fats, minerals, proteins, water, and vitamins.
• %%Colon%%: absorption of water and electrolytes
  • Peyers patches →patches of immune cells that are found in ilium that detect and respond to foreign substances
  • most bacteria found( digest found + ferment food)
• %%Appendix%%: stores immune cells

*Villi: finger-like projections on the surface of the mucosa that increase the surface area for nutrient absorption to the lymphatic system and capillaries

→ they also have mussels to move bolus muscles

**Crypts: small tube-like structures that are located in the lining of the small intestine and the large intestine, produce digestive juices + harbor stem cells for epithelial lining

***Goblet cells: goblet cells secrete mucus that protects the mucosa from damage

**** Squamous cells: are flat and often found in barrier tissues

***** Columnar cells: are taller and typically found in tissues with secretory or absorptive functions.

Pathology of esophagus

• %%Heartburn%%
  • normally prevented by the angle of the stomach and lower esophageal sphincter(LES)
  • gastroesophageal reflux disease→ Barret disease of the esophagus (damaged and replaced by abnormal cells. This is usually caused by long-term acid reflux and is a risk factor for developing esophageal cancer)
• %%Eosinophilic esophagitis%%
  • allergy in the esophagus and a lot of eosinophils → rectaion to what pathogen is unclear maybe food
• %%IBD%%:
• 
• ==Two types of IBD== (systematic disease) → due to a genetic defect, all leukocytes attack microbes and food
  • the peak of onset 20 and 60 → 25% of all IBD start in childhood !!!
  • symptoms come in waves and increase over a lifetime
  • loss of tolerance**
  • impairment of mucosal defense
  • epithelial barrier defects
  • Environmental factors:
  • The earlier the onset, the more genetic the IBD
  • Crohn’s disease
  • vomiting
  • Ulcerative colitis
  • only concerns the colon → a lot of rectal symptoms that crawl upwards
  • (difficult to diagnose because they look so similar (diarrhea with blood+ cramping + fever), but they are very different to treat
  • red blood → inflammation colon
  • black blood → small intestine
  • 
• ==Things that are specific to each disease==
  • Crohn’s
  • the disease can skip passages in the colon and cause inflammation → patchy inflammation
  • Fistulas: abnormal passageways that form between different parts of the body
    • → transmural ( tears through the tissue of them muscle) inflammation → feces can end up in urine
  • granulomas: clusters of cells that form when the body's immune system attempts to contain and eliminate foreign substances or bacteria
  • muscle hypertrophy
  • cobblestone appearance
  • fat wrapping
  • serological marker: ASCA
• @@Ulcerative colitis@@
  • crypt distortions
  • always originates in the rectum and then moves up until half of the colon or the entire colon
  • serological markers: pANCA
  • ulceration within the mucosa
  • in children it does not have to start in rectum
    • 
• 
• {{Manifestation of IBD{{
  • code in the lymph node that triggers an intestine attack
  • you can only have skin irritation and no intestine → due to gene alteration
  • because innate immune system is not working( NOD 2 intracellular bacterial receptor) there is an overload of B and T cells → underlying explanation of IBD
• **Tolerance in immunology
  • there is recognition of everything in our body by the immune system; in a normal state, there is a tolerant state; however, in IBD there is a loss of accepting new things
  • inflammation vs. tolerance ( too much aggressive inflammatory cells or too few protective cells)
• }}Treatment options}}
  • take out the colon in colitis to decrease inflammation →; however, inflammation will always stay because you can’t take out return
  • in crohns you can’t take out the colon because inflammation will continue in small intestines
  • steroids
  • targeted immunosuppression for specific immune cells

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