Digestive

• Upper Gastrointestinal Tract


  Mouth, esophagus, stomach, first part of small intestine (duodenum)
• Lower Gastrointestinal Tract


  Large intestine, cecum, appendix (humans only), colon, rectum, anus
• Functions of the digestive system

  1. Processes ingested food and fluids

  2. Breaks them down into their units

  3. Controlled by enzymes

  4. Absorbs necessary components

  5. Membrane transport mechanisms

  6. Mostly in small intestine
• Common manifestations of digestive system disorders

  • Anorexia
  • Nausea
  • Vomiting
  • Bulimia
  • Diarrhea
  • Constipation
  • Fluid and electrolyte imbalances
  • Pain
  • Malnutrition
• Anorexia


  Eating disorder characterized by restriction of food intake leading to low body weight, typically accompanied by intense fear of gaining weight and disturbed perception of body weight and image
• Causes of anorexia, nausea, vomiting, and bulimia

  • Digestive disorder
  • Other condition elsewhere in the body
  • Systemic infection
  • Uremia
  • Emotional responses
  • Motion sickness
  • Pressure in the brain
  • Overindulgence of food, drugs
  • Pain
• Anorexia and vomiting


  • Can cause serious complications like dehydration, acidosis, malnutrition
  • Anorexia often precedes nausea and vomiting
• Nausea


  Unpleasant subjective feeling simulated by distention, irritation, inflammation of digestive tract, also stimulated by smells, visual images, pain, and chemical toxins and/or drugs
• Vomiting (emesis)


  1. Vomiting center located in the medulla coordinates activities involved in vomiting

  2. Protects airway during vomiting

  3. Forceful expulsion of chyme from stomach, sometimes includes bile from intestine
• Bulimia


  Eating disorder that causes damage to structures of the GI tract due to recurrent vomiting
• Diarrhea


  Excessive frequency of stools, usually of loose or watery consistency, may be acute or chronic, frequently with nausea and vomiting when infection or inflammation develops, may be accompanied by cramping pain, prolonged diarrhea may lead to dehydration, electrolyte imbalance, acidosis, malnutrition
• Fluid and electrolyte imbalances

  • Dehydration
  • Hypovolemia
  • Loss of electrolytes in vomiting and diarrhea
  • Metabolic alkalosis from loss of hydrochloric acid with vomiting
  • Metabolic acidosis from loss of bicarbonate with severe vomiting or diarrhea
• Causes of malnutrition


  • Specific nutrient deficiency (e.g. vitamin B12, iron)
  • Chronic anorexia, vomiting, diarrhea
  • Other systemic causes
  • Chronic inflammatory bowel disorders
  • Cancer treatments
  • Wasting syndrome
  • Lack of available nutrients
• Disorders of the upper gastrointestinal tract

  • Disorders of the oral cavity
  • Dysphagia
  • Esophageal cancer
  • Hiatal hernia
  • Gastroesophageal reflux disease
  • Gastritis
  • Peptic ulcer
  • Gastric cancer
  • Dumping syndrome
  • Pyloric stenosis
• Cleft lip and cleft palate

  Congenital abnormalities that arise in the sixth to seventh week of gestation, most likely of multifactorial origin, cause feeding problems and impaired speech development
• Aphthous ulcers


  Inflammatory lesions in the oral cavity, small painful lesions that usually heal spontaneously, Streptococcus sanguis may be involved
• Oral candidiasis (thrush)


  Opportunistic infection caused by Candida albicans, often in people receiving broad-spectrum antibiotics, during/after cancer therapy, or in immunocompromised individuals or those with diabetes
• Squamous cell carcinoma


  Common type of oral cancer, often develops in persons older than 40 years, associated with smoking and alcohol abuse
• Sialadenitis


  Inflammation of the salivary glands, may be infectious or noninfectious, most commonly affects the parotid gland
• Dysphagia


  Difficulty swallowing, caused by neurologic deficit, muscular disorder, or mechanical obstruction, results in pain with swallowing, inability to swallow larger pieces of solid material, difficulty swallowing liquids
• Esophageal cancer


  Primarily squamous cell carcinoma, significant dysphagia in later stages, poor prognosis due to late manifestations, associated with chronic irritation from conditions like chronic esophagitis, achalasia, hiatal hernia, alcohol abuse, smoking
• Achalasia


  Rare disorder that makes it difficult for food and liquid to pass from the swallowing tube connecting the mouth and stomach
• Hiatal hernia


  Part of the stomach protrudes into the thoracic cavity
• Gastroesophageal reflux disease (GERD)


  Periodic reflux of gastric contents into the distal esophagus causes erosion and inflammation, often seen in conjunction with hiatal hernia, can be managed by avoiding certain foods/substances and using medication
• Acute gastritis


  Gastric mucosa is inflamed, may be ulcerated and bleeding, can result from infection, allergies, irritating foods, excessive alcohol, ingestion of aspirin or NSAIDs, corrosive/toxic substances, radiation or chemotherapy
• Gastroenteritis


  Inflammation of the stomach and intestine, usually caused by infection, may also be caused by allergic reactions to food or drugs
• Peptic ulcer disease (PUD)

  Break in the inner lining of the stomach, first part of small intestine, or lower esophagus, most caused by H. pylori infection, usually occur in the proximal duodenum (duodenal ulcers) or antrum of the stomach (gastric ulcers)
• Factors that predispose to peptic ulcers

  • Inadequate blood supply causing vasoconstriction
  • Excessive glucocorticoid secretion or medication
  • Ulcerogenic substances that break down the mucous layer (aspirin, NSAIDs, alcohol)
  • Atrophy of gastric mucosa and chronic gastritis