GI

• Functions of the gastrointestinal system

  • Ingestion
  • Secretion
  • Mixing and propulsion
  • Digestion
  • Absorption
  • Defecation
• Motility


  The capability of the GI tract to mix and move material along its length
• Mechanical and chemical processes break down ingested food into small molecules
• The absorbed substances pass into blood or lymph and circulate to cells throughout the body
• Feces/Stool


  Wastes, indigestible substances, bacteria, cells sloughed from the lining of the GI tract, and digested materials that were not absorbed in their journey through the digestive tract
• Organs of the digestive system

  • Gastrointestinal (GI) tract (Alimentary tract/Primary organs)
  • Accessory digestive organs (Secondary organs)
• Oral cavity


  The opening of the digestive system where ingestion occurs
• Tonsils


  • Collections of lymphoid tissue in the mucosa of the pharynx surrounding the openings of the nasal and oral cavities
  • Part of Waldeyer's tonsillar ring
• Esophagus


  The tube that transports food from the pharynx to the stomach
• Hiatus


  An opening in the diaphragm through which the esophagus passes
• Deglutition


  The act of swallowing
• Stomach


  A J-shaped organ that lies just below the diaphragm in the upper part of the abdominal cavity primarily to the left of the midline under a portion of the liver
• Small intestine


  The site where most digestion and absorption of nutrients occur, about 20 feet long and folds many times to fit inside the abdomen
• Large intestine


  The terminal portion of the GI tract, responsible for the completion of absorption, the production of certain vitamins, the formation of feces, and the expulsion of feces from the body
• Appendix


  Its function is unclear, but it may play a role in the immune system and act as a storehouse for good bacteria
• McBurney's point


  A point on the abdominal wall that is tender when the appendix is inflamed
• Rovsing's sign


  A sign of appendicitis where pressing on the left lower quadrant causes pain in the right lower quadrant
• Teeth


  Part of the oral cavity that aid in the mechanical breakdown of food
• Salivary glands


  Glands that secrete saliva into the oral cavity
• Liver


  The heaviest gland of the body, weighing about 1.4 kg (about 3 lb) in an average adult, second only to the skin in size, located inferior to the diaphragm and occupying most of the right hypochondriac and part of the epigastric regions
• Liver


  • Divided into two principal lobes - a large right lobe and a smaller left lobe - by the falciform ligament, a fold of the mesentery
• Gallbladder


  A pear-shaped sac located in a depression of the posterior surface of the liver, 7–10 cm (3–4 in.) long and typically hangs from the anterior inferior margin of the liver
• Functions of the liver and bile

  • Synthesis of bile salts
  • Storage of bile
  • Phagocytosis (Kupffer Cells)
  • Activation of vitamin D
  • Carbohydrate metabolism
  • Lipid metabolism
  • Protein metabolism
  • Processing of drugs and hormones
  • Excretion of bilirubin
• Bile


  A physiological aqueous solution produced and secreted by the liver, containing bile salts, phospholipids, cholesterol, conjugated bilirubin, electrolytes, and water
• Bile functions


  • To facilitate lipid absorption and digestion
  • To eliminate waste products from the body
• 1,25(OH)2 D


  The biologically active form of vitamin D, critical for bone building and has other health benefits
• Cholelithiasis/gallstones


  The formation of gallstones in the gallbladder or bile ducts
• Pancreas


  An endocrine and exocrine gland that secretes pancreatic juice containing enzymes for digestion
• Sphincter of Oddi


  A mass of smooth muscle surrounding the hepatopancreatic ampulla that regulates the passage of pancreatic juice and bile into the duodenum
• Pancreatic enzymes


  • Lipase
  • Amylase
  • Protease (Trypsin, Chemotrypsin, Carboxypolypeptidase)
• Acute pancreatitis


  Inflammation of the pancreas that can cause internal hemorrhage
• Spleen


  A fist-sized organ in the upper left side of the abdomen
• Kehr's sign


  Occurrence of acute pain in the tip of the shoulder due to the presence of blood or other irritants in the peritoneal cavity
• Peritoneum

  The largest serous membrane of the body, consisting of a layer of simple squamous epithelium (mesothelium) with an underlying supporting layer of areolar connective tissue, divided into the parietal peritoneum and the visceral peritoneum
• Peritoneal cavity


  The slim space containing lubricating serous fluid that is between the parietal and visceral portions of the peritoneum
• Ascites


  The accumulation of several liters of fluid in the peritoneal cavity in certain diseases
• Retroperitoneal


  Organs that lie on the posterior abdominal wall and are covered by peritoneum only on their anterior surfaces, not in the peritoneal cavity
• Peritoneal folds


  Structures that connect organs to each other or to the abdominal wall
• Rebound tenderness/Blumberg's sign


  A sign of peritoneal irritation
• Enteric Nervous System (ENS)


  The intrinsic nervous system of the gastrointestinal tract, consisting of the myenteric (Auerbach's) plexus and the submucosal (Meissner's) plexus, responsible for regulating gastrointestinal motility and secretion