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

• 

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