MG

Digestive System Notes

Organs and Anatomic Structures of the Digestive System

  • Mouth
    • An opening through which food enters the body.
    • Breaks food into small particles through mastication (chewing) and mixes it with saliva.
  • Tongue
    • Consists mostly of skeletal muscle, attached in the posterior region of the mouth.
    • Provides movement of food for mastication.
    • Directs food to the pharynx for swallowing.
    • Functions as a major organ for taste and speech.
  • Palate
    • Separates the nasal cavity from the oral cavity.
    • Soft Palate: Posterior portion, not supported by bone.
    • Hard Palate: Anterior portion, supported by bone.
  • Uvula
    • A soft, V-shaped structure extending from the soft palate.
    • Directs food into the throat (pharynx).
  • Pharynx (Throat)
    • Performs the swallowing action that passes food from the mouth into the esophagus.
  • Esophagus
    • A 10-inch (25-cm) tube, serving as a passageway for food from the pharynx to the stomach.
    • Peristalsis, involuntary wavelike movements that propel food along the gastrointestinal tract, begins here.
  • Stomach
    • A J-shaped sac that mixes and stores food.
    • Secretes chemicals for digestion and hormones that act locally to control digestive system functions.
    • Cardia: Area around the opening of the esophagus.
    • Fundus: Proximal domed portion of the stomach.
    • Body: Central portion of the stomach, distal to the fundus.
    • Antrum: Distal portion of the stomach.
    • Pylorus: Portion of the stomach that connects to the small intestine.
    • Pyloric Sphincter: Ring of muscle that guards the opening between the stomach and the duodenum.
  • Small Intestine
    • A 20-foot (6-m) tube extending from the pyloric sphincter to the large intestine.
    • Digestion is completed here.
    • Absorption of nutrients (end products of digestion) into the bloodstream takes place through the villi (tiny fingerlike projections lining its walls).
    • Duodenum: The first 10 to 12 inches (25 cm) of the small intestine.
      • Derived from Latin duodeni (meaning 12 each), named in 240 BC by a Greek physician due to its length.
    • Jejunum: Second portion, approximately 8 feet (2.4m) long.
      • Derived from Latin jejunus (meaning empty), named because early anatomists always found it empty.
    • Ileum: Third portion, approximately 11 feet (3.3 m) long, which connects with the large intestine.
      • Derived from Greek eilein (meaning to roll), a reference to peristaltic waves. First used in the early 17th century.
  • Large Intestine
    • Approximately 5 feet (1.5 m) long tube extending from the ileum to the anus.
    • Absorption of water and transit of the solid waste products of digestion take place here.
    • Cecum: U-shaped pouch, the first portion of the large intestine.
    • Colon: Main portion of the large intestine, divided into four parts:
      • Ascending colon
      • Transverse colon
      • Descending colon
      • Sigmoid colon
    • Rectum: Distal portion of the large intestine, approximately 8 to 10 inches (20 cm) long, extending from the sigmoid colon to the anus.
  • Anus
    • Sphincter muscle (ringlike band of muscle fiber that keeps an opening tight) at the end of the gastrointestinal tract.
    • Provides for the elimination of solid waste products of digestion.

Accessory Organs

  • Salivary Glands: Produce saliva, which flows into the mouth.
  • Liver:
    • Produces bile, necessary for fat digestion.
    • Performs many functions related to digestion and metabolism.
  • Biliary Tract (Biliary System): Organs and ducts that transport, store, and release bile.
  • Bile Ducts: Passageways that carry bile.
    • Hepatic Duct: Collects bile formed in the liver.
    • Cystic Duct: Transports bile to and from the gallbladder for storage.
  • Common Bile Duct: Small, tubelike structure where the hepatic and cystic ducts join, conveying bile to the duodenum to aid in fat breakdown.
  • Gallbladder: Small, saclike structure that stores bile produced by the liver.
  • Pancreas:
    • Produces pancreatic juice, which aids in digesting all types of food.
    • Secretes insulin for carbohydrate metabolism.
    • Derived from Greek pan (meaning all) and krea (meaning flesh), first described in 300 BC for its fleshy appearance.

Other Structures

  • Peritoneum: Serous saclike lining of the abdominal and pelvic cavities.
  • Appendix (Vermiform Appendix): Small pouch, attached to the cecum, with no known function in digestion.
  • Abdomen: Portion of the body between the thorax and the pelvis.

Pathway of Food

Food enters the Mouth, then passes through the Pharynx (Nasopharynx, Oropharynx, Hypopharynx), down the Esophagus, into the Stomach, then the Small Intestine (Duodenum, Jejunum, Ileum), into the Large Intestine (Cecum, Ascending colon, Transverse colon, Descending colon, Sigmoid colon, Rectum), and finally expelled through the Anus as feces.

Word Parts of the Digestive System

Combining Forms

  • Digestive System Combining Forms

    • an/o: anus
    • antr/o: antrum
    • cec/o: cecum
    • col/o: colon (large intestine)
    • colon/o: colon (large intestine)
    • duoden/o: duodenum
    • enter/o: intestines (usually the small intestine)
    • esophag/o: esophagus
    • gastr/o: stomach
    • ile/o: ileum
    • jejun/o: jejunum
    • or/o: mouth
    • proct/o: rectum
    • rect/o: rectum
    • sigmoid/o: sigmoid colon
    • stomat/o: mouth

  • Accessory Organs and Combining Forms Used with Digestive System Terms

    • abdomin/o: abdomen, abdominal cavity
    • append/o: appendix
    • appendic/o: appendix
    • celi/o: abdomen, abdominal cavity
    • cheil/o: lip(s)
    • cholangi/o: bile duct(s)
    • chol/e: gall, bile (Note: the combining vowel is e)
    • choledoch/o: common bile duct
    • cyst/o: bladder, sac
    • diverticul/o: diverticulum (pouch extending from a hollow organ)
    • gingiv/o: gum(s)
    • gloss/o: tongue
    • hepat/o: liver
    • herni/o: hernia (protrusion of an organ through a membrane or cavity wall)
    • lapar/o: abdomen, abdominal cavity
    • lith/o: stone(s), calculus (pl. calculi)
    • lingu/o: tongue
    • nas/o: nose
    • palat/o: palate
    • pancreat/o: pancreas
    • peritone/o: peritoneum
    • pharyng/o: pharynx
    • polyp/o: polyp, small growth
    • pylor/o: pylorus, pyloric sphincter
    • sial/o: saliva, salivary gland
    • steat/o: fat
    • uvul/o: uvula

Prefixes

  • a-: absence of, without
  • dys-: painful, abnormal, difficult, labored
  • hemi-: half

Suffixes

  • -ac: pertaining to
  • -al: pertaining to
  • -cele: hernia, protrusion
  • -centesis: surgical puncture to aspirate fluid (with a sterile needle)
  • -eal: pertaining to
  • -ectomy: excision, surgical removal
  • -gram: the record, radiographic image
  • -graphy: process of recording, radiographic imaging
  • -iasis: condition
  • -ia: diseased or abnormal state, condition of
  • -ic: pertaining to
  • -itis: inflammation
  • -lith: stone(s), calculus (pl. calculi)
  • -logist: one who studies and treats (specialist, physician)
  • -logy: study of
  • -megaly: enlargement
  • -oma: tumor, swelling
  • -osis: abnormal condition (means increase when used with blood cell word roots)
  • -pathy: disease
  • -pepsia: digestion
  • -plasty: surgical repair
  • -rrhaphy: suturing, repairing
  • -rrhea: flow, discharge
  • -scope: instrument used for visual examination
  • -scopy: visual examination
  • -stomy: creation of an artificial opening
  • -tomy: cut into, incision
  • -y: noun suffix, no meaning

Diseases and Disorders of the Digestive System

Built from Word Parts

  • Appendicitis: Inflammation of the appendix.
  • Cheilitis: Inflammation of the lips.
  • Cholangioma: Tumor of the bile duct.
  • Cholecystitis: Inflammation of the gallbladder.
  • Choledocholithiasis: Condition of stones in the common bile duct.
  • Cholelithiasis: Condition of gallstones.
  • Colitis: Inflammation of the colon.
    • Antibiotic-associated colitis is caused by Clostridium difficile (C. difficile) bacterium. Symptoms include diarrhea and abdominal pain. Treatments involve stopping the antibiotic, frequent hand washing, and oral vancomycin or other antibiotics directly targeting C. difficile in the colon.
  • Diverticulitis: Inflammation of a diverticulum (pouch).
  • Diverticulosis: Abnormal condition of having diverticula.
  • Dysentery: Painful intestines; a disorder involving inflammation of the intestines (usually the large intestine), associated with abdominal pain and often bloody diarrhea.
  • Enteritis: Inflammation of the intestines.
  • Enteropathy: Disease of the intestines.
  • Esophagitis: Inflammation of the esophagus.
  • Gastritis: Inflammation of the stomach.
  • Gastroenteritis: Inflammation of the stomach and intestines.
  • Gingivitis: Inflammation of the gums.
  • Glossitis: Inflammation of the tongue.
  • Hepatitis: Inflammation of the liver.
  • Hepatoma: Tumor of the liver.
  • Pancreatitis: Inflammation of the pancreas.
  • Peritonitis: Inflammation of the peritoneum. (Note: the final 'e' is dropped from peritone/o in this term).
  • Polyposis: Abnormal condition of having multiple polyps in the mucous membrane of the intestine, especially the colon.
    • Familial polyposis is a syndrome with a high potential for malignancy if polyps are not removed when small.
  • Proctitis: Inflammation of the rectum.
  • Rectocele: Hernia of the rectum.
  • Sialolith: Stone in the salivary gland.
  • Steatohepatitis: Inflammation of the liver associated with excess fat; often caused by alcohol abuse and obesity, which can lead to cirrhosis over time.
    • NASH syndrome (Nonalcoholic steatohepatitis) can occur in nonalcoholic obese patients and/or those with type 2 diabetes mellitus.
  • Stomatitis: Inflammation of the mouth (mucous membrane).
  • Uvulitis: Inflammation of the uvula.

Not Built from Word Parts

  • Adhesion: Abnormal growing together of two peritoneal surfaces that are normally separated; may occur after abdominal surgery. Surgical treatment includes adhesiolysis or adhesiotomy.
  • Celiac Disease (Gluten Enteropathy): A malabsorption syndrome caused by an immune reaction to gluten (a protein in wheat, rye, and barley), which damages the small intestine lining responsible for nutrient absorption.
    • Considered a multisystem disorder with varied signs and symptoms, including abdominal bloating and pain, chronic diarrhea or constipation, steatorrhea (excessive fat in stool), vomiting, weight loss, fatigue, and iron deficiency anemia.
    • A pruritic skin rash called dermatitis herpetiformis may be associated.
  • Cirrhosis: Chronic disease of the liver with gradual cell destruction and scar tissue formation; commonly caused by alcoholism and certain types of viral hepatitis.
  • Crohn Disease (Regional Ileitis or Regional Enteritis): Chronic inflammation of the intestinal tract, usually affecting the ileum and colon.
    • Characterized by cobblestone ulcerations and scar tissue formation, which can lead to intestinal obstruction.
  • Gastroesophageal Reflux Disease (GERD): Abnormal backward flow of gastrointestinal contents into the esophagus, causing heartburn and gradual breakdown of the esophageal mucous barrier.
    • Acidity of regurgitated stomach contents causes reflux esophagitis.
    • May also cause chronic cough and excessive throat clearing.
    • Chronic GERD can cause cellular changes in the lower esophagus called Barrett esophagus, which increases cancer risk.
  • Hemochromatosis: Iron metabolism disorder where too much iron is absorbed from food, leading to excessive iron deposits in tissues.
    • Can cause heart failure, diabetes, cirrhosis, or liver cancer.
  • Hemorrhoids: Swollen or distended veins in the rectum or anus, classified as internal or external, and can cause rectal bleeding and pain.
  • Ileus: Nonmechanical obstruction of the intestine, caused by a lack of effective peristalsis.
  • Intussusception: Prolapse of one part of the intestine inside the part next to it; most common in infants.
    • Symptoms may include intestinal blockage, abdominal pain with cramping, or a palpable lump.
  • Irritable Bowel Syndrome (IBS): Periodic disturbances of bowel function (diarrhea and/or constipation), usually associated with abdominal pain.
  • Obesity: Excess body fat leading to increased body weight.
    • Body Mass Index (BMI) greater than 30 kg/m^2.
    • Overweight is defined as BMI between 25 and 29.9 kg/m^2.
    • Morbid obesity is defined as a BMI over 40 kg/m^2.
  • Peptic Ulcer: Erosion of the mucous membrane of the stomach or duodenum.
    • Associated with increased acid secretion, bacterial infection (H. pylori), or medications like nonsteroidal anti-inflammatory drugs (NSAIDs).
    • Referred to as gastric or duodenal ulcer based on location.
  • Polyp: Tumorlike growth extending outward from a mucous membrane; usually benign.
    • Common sites include the nose, throat, and intestines.
  • Ulcerative Colitis (UC): Disease characterized by inflammation of the colon with ulcer formation, causing bloody diarrhea.
    • Proctocolectomy with permanent ileostomy may be necessary if medical therapy fails.
  • Volvulus: Twisting or kinking of the intestine, causing intestinal obstruction.

Surgical Procedures of the Digestive System

Built from Word Parts

  • Abdominocentesis (Paracentesis): Surgical puncture to aspirate fluid from the abdominal cavity.
  • Abdominoplasty: Surgical repair of the abdomen.
  • Anoplasty: Surgical repair of the anus.
  • Antrectomy: Excision of the antrum (of the stomach).
  • Appendectomy: Excision of the appendix.
  • Cheiloplasty: Surgical repair of the lip.
  • Cholecystectomy: Excision of the gallbladder.
    • First performed in 1882 by a German surgeon. Laparoscopic cholecystectomy was first performed in 1985.
  • Choledocholithotomy: Incision into the common bile duct to remove a stone.
  • Colectomy: Excision of the colon.
  • Colostomy: Creation of an artificial opening into the colon (through the abdominal wall) for stool passage.
    • Creates a stoma, which can be permanent or temporary, used for bowel obstruction, cancer, or diverticulitis.
  • Diverticulectomy: Excision of a diverticulum.
  • Enterorrhaphy: Suturing of the (small) intestine.
  • Esophagogastroplasty: Surgical repair of the esophagus and the stomach.
  • Gastrectomy: Excision of the stomach (or part of it).
  • Gastrojejunostomy: Creation of an artificial opening between the stomach and jejunum.
  • Gastroplasty: Surgical repair of the stomach.
  • Gastrostomy: Creation of an artificial opening into the stomach (through the abdominal wall).
    • Used to insert a