Lecture 19 Flashcards
Function of the Gastrointestinal Tract
Digestion and absorption of food, reabsorption of water and Elimination of wastes
What is the Gastrointestinal tract composed of?
Oral cavity Esophagus, stomach, small and large intestines, rectum (mouth to anus)
Diagnosis of Gastrointestinal Diseases
Fecal analysis (culture, blood), Endoscopic procedures, Radiologic examination (X ray/CT), and MRI/ultrasound
Cleft Lip and Cleft Palate
Maldevelopment leads to defects. Seen in 1 per 1,000 births, Multifactorial inheritance pattern, Upper lip and jaw (cleft lip), Palate (cleft palate). Can lead to liquid aspiration, airway obstruction, feeding difficulties
When and how is Cleft Lip and Cleft Palate fixed
Surgical correction (cheiloplasty)
Cleft lip: Soon after birth
Cleft palate: 1 to 2 years of age with speech therapy to correct nasal speech
How many temporary and permanent teeth do we have?
Temporary or deciduous teeth (20 teeth) formed before birth and emerge in childhood
Permanent teeth (32 teeth) develop in childhood and push on roots to replace temporary set
What antibiotic causes permanent yellow-gray to brown discoloration of the crown of teeth when administered during enamel formation?
Tetracycline
Disease of oral cavity
Diverse collection of aerobic and anaerobic bacteria that mix with saliva, forming sticky biofilm on teeth (dental plaque)
Disease of dental cavity
Loss of tooth structure (decay) from bacterial action (acidic erosion of enamel and decay of dentin (decreased density, softening and discoloration of teeth)
Role of Saliva
Saliva has protective role – prevents dry mouth (xerostoma) have increased risk of cavity development
Gingivitis
Inflammation of the gums due to masses of bacteria and debris accumulating around base of teeth – can lead to periodontal disease
Stomatitis
Inflammation of the oral cavity
Cause of Inflammation of the Oral Cavity
Irritants: Alcohol, tobacco, hot or spicy foods
Infectious agents: Herpesvirus(HSV), HPV, Candida albicans (fungus), bacteria that cause trench mouth – advanced form of gum disease (bleeding, swelling, pain, ulcers)
Canker sores: small painful superficial ulcer of oral mucosa with inflammatory border (red) painful – not contagious
Leukoplakia (Carcinoma of the Oral Cavity)
White lesions - rarely indicate possible dysplasia (20%)
Erythroplakia (Carcinoma of the Oral Cavity)
Depressed red lesions frequently associated with dysplasia and carcinoma
What is so dangerous about oral cancers?
Oral cancers readily metastasize – many nearby LN in head and neck; HPV (serotype 16) – responsible for 75% of head/neck cancers (slow progression – decades)
Esophagus
Muscular tube that extends from pharynx to stomach with sphincters at upper (relaxes to allow passage of swallowed food) and lower (relaxes to allow passage of food to the stomach) ends
Esophageal sphincter dysfunction symptoms
Difficulty swallowing (dysphagia), Substernal discomfort or pain (heartburn-GERD), Inability to swallow (aphagia - complete obstruction), and Regurgitation of food or fluids into trachea causing aspiration, choking and coughing
What does Esophageal sphincter dysfunction cause?
Failure of the cardiac (gastroesophageal) sphincter to function properly, Tears in lining of the esophagus from retching and vomiting from repetitive, intermittent, vigorous contractions that increase intra-abdominal pressure, and Esophageal obstruction from carcinoma, food impaction, or stricture (esophageal webs, rings)
Two major types of disturbances of cardiac sphincter (lower esophageal sphincter-LES)
- Achalasia: Sphincter fails to open properly due to malfunction of nerve plexus; esophagus becomes dilated proximal to constricted sphincter from food retention (inability to swallow)
- Incompetent cardiac sphincter: Sphincter remains open; gastric juices leak back into esophagus (GERD)
Reflux esophagitis
Irritation, Inflammation – Asthma risk
Barrett esophagus
Glandular metaplasia; change from squamous to columnar epithelium - increases risk for cancer
Treatment for cardiac LES dysfunction
Lifestyle modification, diet (alcohol), antacids
Drugs – reduce acid production in stomach (proton pump inhibitors -PPI)
Surgery – if hiatal hernia/esophageal rings
Causes of Esophageal obstruction
Carcinoma (narrows esophagus), Barretts esophagus, Food impaction: improperly chewed food, Stricture (from scar tissue), Hiatal hernia, and esophageal rings
Mallory Weiss syndrome
Caused by retching and vomiting – often related to excess alcohol intake or repeated forced vomiting (Bulimia); tears in the mucosa or lining of esophagus (blood loss)
Heals on its own; may need surgery in repair in severe case
Boerhaave syndrome + treatment
Rupture of esophagus / full thickness perforation – high mortality with treatment (30%) always fatal without surgery and antibiotic Tx
Acute Gastritis
Inflammation of the gastric lining, self-limited inflammation of short duration. Caused by nonsteroidal anti-inflammatory drugs (NSAIDs) that inhibit cyclooxygenase (COX) enzyme: Aspirin, ibuprofen, naproxen and Alcohol (gastric irritant)
COX-1
Promotes synthesis of prostaglandin that protects gastric mucosa
COX-2
Promotes synthesis of prostaglandin that mediates inflammation
Helicobacter pylori Gastritis
Small, gram-negative organisms that colonize the surface of gastric mucosa. They grow within layer of mucus covering epithelial cells lining the stomach. Common infection that increases with age (50% by age 50) – not all are symptomatic. Spreads from person-to-person through close contact and fecal–oral route
Peptic Ulcer pathogenesis and complications
Digestion of mucosa due to increased acid secretions and digestive enzymes (gastric acid and pepsin) or H. pylori injures mucosa directly and through stimulation of increased acid secretion by gastric mucosa (found in the Distal stomach or proximal duodenum)
Complications: Chronic hemorrhage (ulceration erodes into blood vessel), perforation (erosion through wall – exit of gastric contents into peritoneal cavity – peritonitis), and obstruction from scarring
Peptic Ulcer Treatment
Antacids, PPI, Antibiotic therapy: Against H. pylori (90% effective), or Surgery if medical therapy fails or to correct perforations
Carcinoma of the Stomach (+treatment and diagnosis)
Causes Vague upper abdominal discomfort and Iron-deficiency anemia (chronic blood loss from ulcerated surface of tumor)
Diagnosis: Biopsy by means of gastroscopy
Treatment (survival rate poor):
Surgical resection of affected part, surrounding tissue, and lymph nodes
Can be combined with radiation and chemotherapy
Acute enteritis
Intestinal infections; common; of short duration, Commonly rotavirus (infants, children – oral/fecal) or norovirus (adults – highly contagious ); Abrupt onset : nausea, vomiting, abdominal discomfort, diarrhea
Bacterial enteritis
Similar to viral infection in mild cases, but depending on strain and infection can be more severe (toxin production): Common agents: Vibrio chloerae, E. Coli– severe cases can lead to prolonged disease and ulceration in severe infection and may produce bloody diarrhea (major cause of death in developing countries)
Food intolerance symptoms
Crampy abdominal pain, distention, flatulence, loose stools
Lactose intolerance
Unable to digest lactose into glucose and galactose for absorption due to lactase deficiency
Enzyme abundant in infants and young children – reduction with aging
Genetic component: common in almost all adults of Asian decent; 90% of Native Americans; 70% of African decent , 20% Caucasian decent
Celiac disease (diagnosis + treatment)
Gluten intolerance, immune related disorder T cell mediated – primarily in small intestine. Causes chronic diarrhea impairs absorption of fats and nutrients; weight loss – poor growth, vitamin deficiencies that can lead to anemia
Diagnosis: Clinical features (steatorrhea), CT scan (inflammation, wall thickening) endoscopy and biopsy of intestinal mucosa, presence of anti- transglutaminase antibodies
Treatment:
Gluten-free diet
Drugs used in refractory disease (Steroids, immune suppressants)
Irritable Bowel Syndrome (diagnosis + treatment)
Episodes of crampy abdominal discomfort, loud gurgling bowel sounds, and disturbed bowel function without structural or biochemical abnormalities
Diagnosis made by exclusion – no structural or biochemical anomalies
Treatment: Identify foods/conditions that may precipitate episodes (stress/anxiety), Improve intestinal motility (high fibre, low sugar diet), and Reduce emotional tension - counselling/antidepressants
Appendix
Appendix projects from proximal colon (fingerlike), Evidence of past importance in predominant vegetable diet (Enlarged in some herbivores - rabbit, horse), Important in immune function
Appendicitis (diagnosis and treatment)
Most common inflammatory lesion of the bowel; Secretions of appendix drain poorly, create pressure in appendiceal lumen, compressing blood supply and Bacteria (normally present) invade appendiceal wall, causing inflammation
Abdominal pain + CT, ultrasound, and blood tests (+WBC) to check
Treatment: Antibiotics, Surgery – removal to avoid rupture
Chronic Enteritis (2 types)
Less common, and more difficult to treat than acute enteritis (Chron’s disease and Chronic ulcerative Colitis); Characterized with periodic flare ups/remissions, systemic manifestations (joint inflammation) with genetic and environmental components (immune related, not autoimmune)
Crohn’s disease (symptoms + treatment)
Chronic inflammation and ulceration of mucosa with thickening and scarring of entire bowel wall (full thickness), Causes cramping, diarrhea (bloody/mucous), fatty (steatorrhea), Inflammation may be scattered with normal intervening areas, or skip areas, Increased risk of cancer, and Mouth to anus (most commonly terminal ileum)
Treatment: Drugs (corticosteroids) and possible surgical resection of affected part of bowel
Ulcerative colitis (symptoms + treatment)
Large intestines and rectum; Inflammation is limited to the mucosa, bowel is not thickened, (unlike in Crohn’s disease). Causes bloody diarrhea, and perforation, and can develop into cancer of the colon/rectum
Treatment: Antibiotics and fluids, corticosteroids, immunosuppressive drugs, and surgical resection
Antibiotic-associated colitis (Symptoms, Diagnosis, and treatment)
Broad-spectrum antibiotics destroy normal intestinal flora which will allow anaerobic spore-forming bacteria (Clostridium difficile) which produce toxins, causing inflammation and necrosis (Diarrhea, abdominal pain, fever)
Diagnosis: Stool culture: detection of bacterial toxin in stool
Treatment: Stop antibiotic treatment; give vancomycin or metronidazole – pulse therapy and fecal transplant
Intestinal Obstructions (+ causes)
Always serious but severity depends on the location of obstruction, completeness, interference with the blood supply
Common causes of intestinal obstruction are adhesions, hernia, tumors, volvulus, intussusception or cancer
High (or upper) intestinal obstruction (small intestine) symptoms
Severe, crampy abdominal pain from vigorous peristalsis and Vomiting (often bilious) with loss of H2O and electrolytes, may result in dehydration
Low intestinal obstruction (large intestine) symptoms
Symptoms less acute and less severe (larger space, harder to obstruct); Mild, crampy abdominal pain, and
Moderate distention of abdomen
Adhesions Intestine
Adhesive bands of connective tissue that form within the abdominal cavity that cause loop of bowel to become kinked, compressed, and twisted
Hernia (Types)
Protrusion of loop of bowel through a small opening, usually in the abdominal wall. Types: Inguinal, umbilical, femoral
Inguinal hernia
Common in men; loop of small bowel protrudes through a weak area in inguinal ring and descends downward into scrotum
Umbilical hernia
Common in both sexes; Loop of bowel protrudes into umbilicus through defect in the abdominal wall
Femoral hernia
Common in both sexes; Loop of intestines extends under inguinal ligament along course of femoral vessels into the groin
Reducible hernia
Herniated loop of bowel can be pushed back into abdominal cavity
Incarcerated hernia
Cannot be pushed back
Strangulated hernia
Loop of bowel is tightly constricted, obstructing the blood supply to the herniated bowel; requires prompt surgical intervention to prevent infarction (halt of blood flow)
Volvulus
Rotary twisting of bowel and mesentery commonly seen in the sigmoid colon- leading to bowel obstruction and impairment of blood supply (occurs in infants and patients with adhesions
Intussusception
Telescoping of a segment of bowel into adjacent segment which can cause a bowl infarction. Can be congenital, an infection (children), or a tumor (adults). Treatment: surgery
Mesenteric Thrombosis
Thrombosis of superior mesenteric artery, may develop arteriosclerosis and cause obstructions that create extensive bowel infarction
Diverticulosis (+complications)
Asymptomatic outpouchings or diverticula of colonic mucosa through weak areas in the muscular wall of large intestine (diverticula) - sigmoid colon. Those with low-fiber diets are predisposed
Complications: Inflammation, perforation, bleeding, scarring, abscess
Diverticulitis
Fecal matter can be trapped causing inflammation
Tumors in the colon
Uncommon (usually found in the large intestine) and is easily treatable in the colon. If it metastasizes the 5 year survival rate will decrease from 90% to 14%. Cancers are commonly associated with inherited or sporadic mutations in APC gene, Ras gene, and p53
Benign pedunculated polyps
Frequent, Tips of polyps may erode which causes bleeding, and can be detected and removed by colonoscopy (mutation of Ras gene)
p53 gene
Mutation in this gene causes loss of function which results in invasive colon cancer
Cancer in which part of the GI tract does not cause destruction and why?
Cancer in the Cecum and proximal colon does not cause obstruction because caliber is large and bowel contents are relatively soft (can lead to chronic iron-deficiency anemia due to bleeding)
Side note: cancer in distal parts cause obstruction
Hemorrhoids
Example: Varicose veins are predisposed to development from pregnancy, constipation, and straining (having a fiber rich diet can combat this)
Internal hemorrhoids
Involve veins of the lower rectum and may erode and bleed, become thrombosed, or prolapse though anus
External hemorrhoids
Veins of anal canal and perianal skin may become thrombosed, causing discomfort
Obesity
Chronic and progressive disease, influenced by a variety of genetic, environmental, emotional/mental health factors also sometimes caused by endocrine or metabolic disturbances which increase health risk
Risk of obesity
Higher incidence of diabetes (inability to use insulin), hypertension, cardiovascular disease, and many other diseases. This excess fat is harmful to the CVS (High BP and Atherosclerosis), respiratory system (ventilation, weight on chest), and musculoskeletal system. Can have effects on your mental health.
Obesity: Treatment
Reduction of food intake and increase in activity (small weight losses can have significant health benefits). Those who are unable or unwilling to reduce their caloric intake can use Ileal bypass, Gastric bypass, and Adjustable gastric banding
Bariatric surgery (Gastric Bypass)
Goal is to restrict the capacity of the stomach without compromising nutrient adsorption. This can lead to complications from poor absorption like anemia and osteoporosis
Anorexia Nervosa
A mental health issue that has a false perception of weight excess – actually too thin
Continual weight reduction by food restriction and excessive exercise. Causes malnutrition, loss of menstrual function, thyroid decline, fluid and electrolyte imbalance –can lead to death
Bulimia Nervosa
Mental health disorder that causes repeated episodes of binge eating followed by purging (hard to detect). Leads to dental problems (erosion from gastric acids), metabolic alkalosis (from loss of gastric acid), and electrolyte disturbances
Chronic Malnutrition: starvation
Caused by insufficient intake of nutrients; cannot supply the body’s needs. Losing 30% of body’s Those who are at risk include children/elderly, poverty, cancer, eating disorders, drug/alcohol abuse
Alcoholism and its role in malnutrition
High-calorie non-nutrient, 7calories per gram (feeling full but getting no nutrients)
Kwashikor (famine)
Diets sufficient in calories, but lacks protein (severe edema and skin abnormalities), hair takes on red color. Intestinal changes are hard to reverse, even with proper diet – diarrhea likely
