GI system

layers of the GI tract

serosa- outer most layer

muscularis

submucosa

mucosa

serosa

connective tissue layer

peritoneum

muscularis

circular muscle layer

longitudinal muscle layer

mucosa

mucous epithelium

lamina propria

muscularis mucoseae

digestive process

1) cephalic phase

2) gastric phase

3) intestinal phase

cephalic phase

secretion of acetylcholine (PSNS), gastrin, & histamine

gastric phase

• parietal cells- secrete HCl; Acetylcholine, histamine, and gastrin binds and triggers proton pump (increase H+ ion)

• Goblet cells- secrete mucus, release digestive enzymes, and absorb nutrients

• Chief cells- secrete pepsinogen → pepsin

• Gastric mucosal cells - secrete prostaglandin E2 (PEG2); PEG2 stimulates gastric mucus production and bicarb secretion, decrease effects of HCl

• G cells (gastrin cells located in the pylorus) -stimulate secretions from parietal and chief cells

Intestinal phase

small intestine first, then large

3 parts of stomach

fundus, body, antrum

typical questions of GI assessment

swallowing, indigestion, weight loss, appetite, nausea/vomiting, pain, elimination, family history

substances affecting upper GI

alcohol, smoking, nasaids

diagnostic tests

upper and lower GI endoscopy

videocapsule endoscopy

laparoscopy(scope) and laparotomy(open)

upper GI series (barium study)

H.Pylori antibody (blood)

constipation

defined as infrequent or difficult defecation

diarrhea

increased frequency of bowel movements

increased volume, fluidity, weight of the feces

major mechanisms:

1. osmotic diarrhea

2. secretory diarrhea

3. motility diarrhea

osomotic diarrhea

malabsorption syndromes (lactose intolerance); laxatives

mild

secretory diarrhea

infections (toxins), medications (chemo)

severe

motility diarrhea

irritable bowel

two issues that occur with reflux

1. relaxation of the les (inadequate closure)

2. Gastroparesis- delayed emptying from the stomach to duodenum

contributing factors of GERD

laying flat or bending over, alcohol, chocolate, coffee, fatty meals, obesity, pregnancy, some medications, nicotine, hiatal hernia

Hiatal Hernia

part of the stomach pushes up through the opening in the diaphragm and protruding into the thoracic cavity

allows stomach acid to reflux back into esophagus

many are undiagnosed, asymptomatic, and discovered incidentally

lifestyle changes for GERD and Hiatal Hernia

weight loss, small meals, coffee limitation, smoking cessation, refrain from lying down after eating, sleeping with the head of bed elevated

avoiding certain foods

Obstruction

any condition that prevents the flow of chyme through the intestinal lumen

• can be partial or complete

• can be SBO or LBO

Ileus

failure of normal intestinal motility (in the absence of an obstructing lesion)

Ileostomy

the ileum of the small intestine is surgically brought out to the exterior abdominal wall through an incision in the anterior abdominal wall

colostomy

the colon is imilarly brought out to the anterior abdomen

acute gastritis

inflammatory disorder of the gastric mucosa

diagnosis is confirmed with endoscopy and a biopsy of the affected tissue

chronic gastritis or nonerosive gastritis

presence of the H. pylori is most common cause

causes atrophy of the stomach lining

precursor for stomach cancer

Peptic Ulcer disease (PUD)

inflammatory erosion in the stomach or duodenal lining

ulceration occurs 4x more often in the duodenum than stomach

endoscopy and tissue biopsy

pathophysiology of PUD

hyper secretion of HCl

ineffective GI mucus production

poor cellular repair

Irritable bowl syndrome (IBS)

recurrent abdominal pain and discomfort associated with altered bowel habits

diarrhea or constipation, or both

IBS Risk factors

female, under 40, family history, stress, a person may have food triggers

esophageal cancer

• risk factors: male, gerd & barrett’s esophagus, chronic alcohol consumption, particularly whiskey , tobacco use, genetic markers

• pathophysiology: chronic irritation of the epithelial cells cause cellular injury and leads to metaplastic changes, metaplastic becomes dysplasia, proliferation of cancer cells

• symptoms: dysphagia, change in eating patterns, weight loss, dyspepsia, sore throat/hoarseness, cough

colorectal cancer

half of all colon cancers occurs in the rectosigmoid area

• risk factors: genetic factors are highest risk, polyps, red meat, obesity, sedentary life, insulin resistance, tobacco, alcohol