GI pathophysiology

upper GI system

mouth, esophagus, stomach, duodenum

ingestion and digestion

lower GI system

small intestines: digestion and absorption of nutrients

large intestines: absorption of water, electrolytes, storage of waste

GI bleeding

characterized by

-coffee ground emesis

-hematemesis

-melena

-hematochezia

hematemesis

vomiting of bright red blood

melena

black, tarry stool

hematochezia

bleeding from the rectum, or maroon colored stools

older adults

more likely to develop diverticulitis and atrophic gastritis

diverticulosis

small out pouches of the intestine

can become inflamed

mucosal villi and folds

lost with aging

leads to a reduction of absorption capacity

parietal cells

present in the stomach

produce HCL for digestion and gastric intrinsic factor for B12 absorption (both are reduced with aging)

Pernicious anemia

a lack of chronic gastric intrinsic factor (GIF) and absorption of B12

Pernicious anemia treatment

patients are treated with B12 shots and supplementation

typically results in a full recovery

esophagitis

inflammation of the esophagus

more commonly is chronic secondary to GERD or cancer

GERD

occurs when stomach contents (gastric acid) enters the esophagus

most common pathogenesis is due to dysfunction of the lower esophageal sphincter

Barrett esophagus

a precancerous change in the type of cells that line the lower end of the esophagus (columnar cells replace squamous cells)

Mallory weiss syndrome

tears in the lower esophagus develops from bulimia

results in hematemesis

persons with alcohol use disorders are at a higher risk

Hiatal hernia

herniation of the stomach through the diaphragm

commonly caused by increases in intrabdominal pressure

scleroderma

esophageal muscle atrophy and collagen replace muscle leading to esophageal dysmotility and dysphagia

loss of motility present on a barium swallow study

esophageal tumor

most are in the lower 1/3 of the esophagus

causes obstruction which leads to dysphagia, odynophagia, and bleeding

achalasia

loss of autonomic control of the myenteric plexus, submucosal plexus

results in failure of the lower esophageal sphincter to relax when swallowing and allow food to enter the stomach

accumulation of food will cause dilation

tracheo-esophageal fistula

communication between the trachea and esophagus

children will have the 3 Cs

1. cough

2. cyanosis

3. choking

commonly leads to aspiration pneumonia

acute gastritis

acute inflammation of the stomach mucosal lining

peptic ulcer disease

H. pylori cause local erosion of the mucosa and mucus barrier

-decreases barrier function

-back diffusion of HCl with tissue erosion

-stimulation of H2 (histamine) receptors

1. histamine release from ECL

2. vasodilation and bleeding

3. stimulate parietal cells

   1. more gastric acid releases

gastric adenocarcinoma

most common stomach cancer

stomach cancer

the 5th most common cancer in the world

commonly linked to H pylori or epstein barr

genetic factors

malabsorption

limited absorption of nutrients

results in poor nutrition or malnourishment

celiac disease

immune mediated disorder triggered by gluten induced

intestinal villi are lost

Chron’s disease

a type of inflammatory bowel disease

autoimmune disease: terminal ileus and colon are most common sites

enteropathic arthritis-can lead to joint pain

physiologic obstruction

loss of peristalsis or Ileus

Results in fecal impaction

Mechanical obstructions

post surgical adhesions

fibrous bands of scar tissue create bridges through which intestine can slide and become trapped or by creating an axis around which the bowel can twist

can result in a volvulus

Intussusception

telescoping of the bowel into itself

hernia

protrusion of the small intestine through the peritoneal cavity

often attributed to muscle weakness

Hirschsprung’s disease

congenital ileus

bowel becomes enlarged and static

pediatrics

right lower quadrant

where pain occurs with appendicitis

IBS

most common GI disorder