GI Tract

What is the main purpose of the GI tract?

Digestion and absorption of nutrients.

What is the order of events in the GI tract?

Food enters the mouth, where saliva increases the moisture, esophagus when swallowed, the stomach to mixed with gastric secretions, small intestines to be emulsified, colon, rectum.

What vitamins are produced by intestinal bacteria?

Produce vitamin K and folic acid to prevent harmful bacterial infections.

What is the role of the smooth muscle in the GI tract?

Contract to move things along.

Why is the GI tract vulnerable to disease?

It is open to the environment and populated by billions of bacteria.

What often causes GI disease due to a barrier breach?

Bacteria entering the bloodstream or surrounding tissues.

Why is mechanical malfunction common in the GI tract?

Because peristalsis and movement of contents are essential and easily disrupted.

Why is the GI tract prone to hemorrhage?

It is richly vascular.

Which organ hosts more neoplasms than any other?

The colon.

What do most colon cancers arise from?

Long-standing benign polyps.

What does slow bleeding of the GI (e.g., from malignancy) commonly cause?

Iron deficiency anemia.

Hematemesis (define and 2 types)

Vomiting blood

Red blood from the esophagus

Black blood from the stomach

Hematochezia

Blood in stool

Melena

Black, tarry stool from digested blood.

GI bleeding is assumed to be caused by what until proven otherwise?

Malignancy.

What is often the first sign of precancerous colon lesions?

Occult (hidden) GI bleeding. The easiest way to determine is to see if there is blood in the stool.

What structures are involved in upper GI bleeding?

Esophagus, stomach, first inches of duodenum.

Major causes of upper GI bleeding?

Acute hemorrhagic gastritis, peptic ulcer, and esophageal tears from vomiting or varices.

Major causes of lower GI bleeding?

Enterocolitis, colonic diverticulitis, neoplasms, colonic angiodysplasia.

Enterocolitis

Inflammation of small and large intestines

Colonic Divertuculitis

Out pouching of the colon, fecal matter will collect there, causing bacteria.

Colonic Angiodysplasia

Painless bleeding in the right colon

(low volume venous bleeding)

What is peristalsis essential for?

Peristalsis is the contraction of the smooth muscle, which is critical for normal GI function and movement.

What is ileus?

Temporary paralysis of bowel movement.

Causes of ileus?

Post op from abdominal surgery, inflammation, ischemia, and hypokalemia (low blood potassium).

Causes of mechanical GI obstruction?

Hernia, adhesions, intussusception (inversion of intestine) , volvulus.

Incarcerated hernia

A hernia that is swollen and fixed within a sac, causing an obstruction

Strangulated hernia

A portion of the intestine is twisted

What reduces periodontal disease?

Fluoridated water and good oral hygiene.

What characteristics commonly lead to a higher risk for moral cancer?

Poor oral hygiene, alcohol, and tobacco.

What are aphthous ulcers?

Canker sores.

What is candidiasis?

A fungal infection.

What type of carcinomas are oral cancers?

Squamous cell cancers (from poor oral hygiene, alcohol, and tobacco).

What is dysphagia?

Difficulty swallowing.

Causes of dysphagia?

Hiatal hernia, scar tissue, tumors, abnormal peristalsis.

What is GERD?

Gastroesophageal reflux disease where the stomach acid will move into the esophagus.

Wat is achalasia?

Spasm/failure of relaxation of esophageal sphincter.

What is Mallory-Weiss syndrome?

Esophageal lacerations due to severe vomiting.

What causes esophageal varices?

Portal hypertension due to liver cirrhosis.

What percent of deaths from varices occur during the first bleed?

About 50%.

Most common esophageal cancer?

Squamous cell carcinoma.

What is Barrett's metaplasia?

Epithelium changes stratified squamous to simple columnar, in response to GERD. Increases the risk for esophageal disease by 40 times.

Who is at highest risk for esophageal disease?

Men, alcolol abuse, tobacco. poor prognosis if not caught early.

What causes acute gastritis?

NSAIDs and alcohol abuse.

What causes chronic gastritis?

Autoimmune mechanisms or H. pylori infection.

What are the two types of gastric and duodenal ulcers?

Stress ulcers and peptic ulcers.

What are stress ulcers in the gastric or duodenal?

Multiple acute superficial defects caused by trauma, surgery, sepsis, etc.

Characteristics of peptic ulcers?

Chronic, deep, solitary lesions.

What is required for peptic ulcer development?

H. pylori infection with chronic gastritis risk factors.

Where are peptic ulcers most common?

Duodenum

#1 cause of US cancer death in the 1930s?

Stomach cancer.

Major risk factors for stomach cancer

H. pylori, chronic gastritis, smoked/salted/pickled foods, nitrite preservatives, low fresh produce.

Why is mortality high for carcinomas in the stomach?

Early detection is very rare.

Why is bowel infarction dangerous?

Difficult to diagnose and often fatal if occluded. Can happen from atherosclerosis, embolisim, volvus, CHF. Ileus often occurs.

What is angiodysplasia?

Congenital malformation of vessels, fragile blood vessels in the colon, causing bleeding.

What are hemorrhoids?

Dilated veins of the anorectal region.

What is the risk of diarrheal disease?

Severe dehydration

What is dysentery?

Diarrhea with blood and mucus.

What is IBS?

Irritable bowel syndrome — a functional disorder without structural pathology. Causes periods of diarrhea followed by constipation.

What is enterocolitis?

Inflammation of the colon and small intestine (entera)

What is malabsorption?

Impaired nutrient absorption.

Causes of luminal malabsorption?

Lipase deficiency, bile salt deficiency.

Causes of intestinal malabsorption?

Lactose intolerance; celiac disease.

Complications of malabsorption?

***Truly depends on the nutrients that are not being absorbed.

Anemia, excessive bleeding, musculoskeletal issues, hormonal skin & neurologic disorders.

What are the two major IBDs?

Crohn disease and Ulcerative colitis.

What are the characteristics that Crohn's disease and Ulcerative colitis share?

Episodic bloody diarrhea, autoimmune etiology, genetic influence, extraintestinal effects.

Pathology of Crohn's?

AI dieasse producing granulomatous inflammation anywhere from mouth to anus (terminal ileum most common). Affects young white women.

Pathology of ulcerative colitis

Superficial, non-granulomatous inflammation limited to the colon. affects men and women of all races.

What forms a diverticulum?

Mucosa and submucosa herniate through the muscle wall. Very uncommon is a high fiber diet.

What causes infection in colonic diverticulosis?

Bacteria proliferate on trapped fecal matter.

What is peritonitis?

Inflammation of the peritoneum due to bacteria or leakage of bowel contents.

Are small bowel tumors common?

No, they are very rare

What types of colon tumors exist?

Non-neoplastic polyps, neoplastic adenomas, carcinomas.

How long does it take for adenomas to become malignant?

10-15 years

What determines cancer risk?

Type and size of the polyp

What is often the first sign of colon cancer?

Iron deficiency anemia.

Iron deficiency anemia in an adult male or post-menopausal woman means what until proven otherwise?

Intestinal carcinoma.

Most are what type of cancer?

Adenocarcinomas of epithelial cells.

Time required for adenoma → carcinoma?

10 years or more

Common symptoms of colon carcinoma?

Weight loss, bowel changes, bleeding, anemia, pain, and metastatic symptoms.

Has metastasis usually occurred by the time symptoms appear in colon carcinomas?

Yes!

What is CEA?

Carcinoembryonic antigen tumor marker. Proven ineffective because levels are rarely elevated when the cancer is curable.

What else increases CEA?

Smoking, pancreatitis, other tumors.

Stool occult blood test detects what % of cancers?

About 50%; reduces mortality by 30%.

Colonoscopy recommendations?

At age 50: every 5 years if high risk, every 10 years if not; reduces mortality by 60%.

Most common age group for appendicitis?

Teenagers and young adults (males > females).

What are the symptoms of appendicitis?

Abdominal discomfort, anorexia, nausea, vomiting, fever, RLQ pain.

Main danger of appendicitis?

Rupture or perironitis