GI pathophysiologyReview section

Bios E-162b, Dec 5, 2010

http://en.wikipedia.org/wiki/File:Digestive_system_diagram_edit.svg

Overview of the GI system

http://www.youtube.com/watch?v=Z7xKYNz9AS0

Transit of foodstuffs through the GI system

The wall of the GI tract has several layers

Sphincters control the transit from one section of the GI tract to the next

www.mydr.com.au

Bile and pancreatic secretions are emptied at the same point in the duodenum

www.memorialhermann.org

The enteric nervous system regulates GI activity

mikedaisey.com

GI hormones also regulate GI activity

04340.com

Gastroesophageal reflux is due to an insufficient closure of the lower esophageal sphincter

www.webmd.com

myhealth.ucsd.edu

Hiatus hernias may also cause gastroesophageal reflux

Several factors may cause or aggravate GER

- Young age- Obesity- Pregnancy- Postural changes after eating- Smoking- Peppermint, coffee, alcohol- Diseases of connective tissue

Gastric metaplasia of the esophageal epithelium

GER may lead to Barrett’s esophagus

www.lwjuan.com

Barrett’s esophagus mat lead to esophageal adenocarcinoma

upload.wikimedia.org

The stomach mucosa produces acid, mucus and pepsinogen

Several mediators induce acid secretion

Peptic ulcers come from an imbalance between acid vs. mucus + HCO3

www.yourgicenter.com

H. Pilori is the most common cause

bioweb.uwlax.edu

H. Pilori is the most common cause

upload.wikimedia.org

The digestion of carbohydratesMost dietary carbs are polysaccharides

Cooper GM. The Cell: A Molecular Approach. 2nd edition.

The digestion of carbohydratesAll carbohydrates are converted to

monosaccharides before absorption

salivary a-amilase

5% starch Maltose

salivary a-amilase

25% starch Maltose

pancreatic a-amilase

70% starch Maltose

The digestion of carbohydratesDisaccharidases at intestinal villi transform

disaccharides in monosaccharides

web.campbell.edu

The digestion of fats

Types of diarrhea

Osmotic

Secretory

Malabsoptive

ie. Lactose intolerance

ie. Cholera

ie. Celiac disease

Inflammatory ie. Chron’s disease

High motility ie. Some medications